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HISTOPATHOLOGICAL ANALYSIS OF PROSTATIC CANCERS IN
FEDERAL MEDICAL CENTRE KEFFI
A DISSERTATION
BY
DR GARBA A. YAKUBU
DEPARTMENT OF PATHOLOGY
JOS UNIVERSITY TEACHING HOSPITAL
IN PARTIAL FULFILLMENT OF REQUIRMENT FOR PART II FINAL
FELLOWSHIP EXAMINATION OF THE NATIONAL
POSTGRADUATE MEDICAL COLLEGE OF NIGERIA (NPMCN) IN
PATHOLOGY
2
SUPERVISORS
PROF. B. M. MANDONG MBBS, FMCPath
CONSULTANT PATHOLIGIST
JOS UNIVERSITY TEACHING HOSPITAL
JOS
________________________________
SIGN
DR B. A. ABIMIKU MBBS, FMCPath, FICS
CONSULTANT PATHOLOGIST
UNIVERSITY OF ABUJA TEACHING HOSPITAL
GWAGWALADA, ABUJA
___________________________________
SIGN
3
DECLARATION
I declare that this work is original. It has not been presented to any college for a
fellowship neither has it been submitted elsewhere for publication
---------------------------------------
Dr Garba, A. Y.
PROF. B. M. MANDONG MBBS, FMCPath
CONSULTANT PATHOLIGIST
JOS UNIVERSITY TEACHING HOSPITAL
JOS
________________________________
SIGN
DR B. A. ABIMIKU MBBS, FMCPath, FICS
CONSULTANT PATHOLOGIST
UNIVERSITY OF ABUJA TEACHING HOSPITAL
GWAGWALADA, ABUJA
___________________________________
SIGN
4
DEDICATION
This work is dedicated to God Almighty, the creator of all mankind, my wife
Rhoda Yakubu, my sons Ernest and Kyuni Yakubu, my daughters, Joan, Suzan
and Opeyemi Yakubu, my late parents and my entire family for the
understanding, support and encouragement during the period of this study.
It is also dedicated most importantly to all men who have suffered the agony of
prostatic disease.
5
ACKNOWLEDGEMENT
My profound gratitude goes to the following people for their endless support
and contributions during the course of this study: Professor B. M. Mandong for
his untiring support, constructive criticism, supervision and guidance
throughout the study period, Dr B. A. Abimiku for his tremendous
encouragement, advice and supervision, Dr O. A. Silas and Dr M. D. Ayuba,
Former Head of Department and Present Head of Department, Histopathology,
Jos University Teaching Hospital; for their encouragement and support.
Also worthy of acknowledgement are all the Consultants in the Department of
Histopathology, Jos University Teaching Hospital, Dr Paul Jibrin and Mr
Jonathan Madukwe of the Department of Histopathology, National Hospital,
Abuja, for their assistance regarding the immunohistochemical study, Miss
Julyan Gye for preparing all the H & E slides, Dr Joshua Giyan, Medical
Director, Federal Medical Centre, Keffi for all his support and assistance, Dr
Yahaya Bawa Ubam HCS, Federal Medical Centre, Keffi, all the staff of
Histopathology Laboratory, Federal Medical Centre, Keffi for their assistance in
sorting out tissue blocks and histology reports.
My thanks also go my wife, Rhoda Yakubu for her understanding and
endurance, my children, Ernest, Joan, Susan, Opeyemi and Kyuni for their
patience and endurance, and Mr Jared Alaku for his secretarial assistance.
6
It is my sincere prayer that Almighty God grants you all your desires and may
you all live long.
7
TABLE OF CONTENTS
Title Page………………………………………………………………… i
Supervisors………………………………………………………………. ii
Declaration………………………………………………………………. iii
Dedication……………………………………………………………….. iv
Acknowledgement………………………………………………………. v
Table of Contents………………………………………………………… vii
List of Figures…………………………………………………………… xi
List of Tables……………………………………………………………. xiii
Abstract………………………………………………………………….. xiv
Chapter One………………………………………………………………. 1
1.1 Introduction…………………………………………………….. 1
1.1.1 Histological and immunohistological methods of diagnosis…… 4
1.2 Statement of the problem………………………………………. 5
1.2.1 Justification of the study……………………………………… 5
Chapter Two………………………………………………………………. 7
2.0 Literature review……………………………………………….. 7
2.1 An overview……………………………………………………. 7
2.2 Epidemiology…………………………………………………… 7
2.3 Aetiology……………………………………………………….. 9
2.3.1 Proven risk factors……………………………………………. 10
2.3.2 Probable risk factors…………………………………………. 10
2.3.3 Potential risk factors…………………………………………. 11
8
2.4 Pathogenesis……………………………………………………. 11
2.4.1 Gluthathoine S-Transferese (GSTP1)……………………….. 12
2.4.2 Somatic Genetic Alterations and Prostatic Cancer …………. 12
2.4.3 Tumour suppressor genes and loss of heterozygosity………. 13
2.5 Oncogenes / growth promoting genes………………………. 14
2.5.1 Androgen receptor………………………………………….. 14
2.5.2 Gene fusion…………………………………………………. 15
2.5.3 Oncogenic tyrosine kinases…………………………………. 15
2.5.4 EZH2 (Enhancer zest 2)…………………………………….. 15
2.5.5 BRCA2……………………………………………………… 15
2.6 Pathological features………………………………………… 16
2.6.1 Morphology……………………………………………….. 16
2.7 Criteria for histologic diagnosis…………………………….. 21
2.7.1 Major criteria……………………………………………… 21
2.7.2 Minor criteria……………………………………………… 21
2.8 Clinical presentation………………………………………… 21
2.9 Diagnosis……………………………………………………. 22
2.10 Tissue diagnosis……………………………………………. 23
2.10.1 Histochemical and immunohistochemical features……… 24
2.11 Histologic grading………………………………………….. 24
2.11.2 2005 ISUP modified Gleason system…………………….. 27
2.12 Prognosis……………………………………………………. 28
Chapter Three…………………………………………………………… 30
9
3.1 General objectives……………………………………………. 30
3.2 Specific objectives……………………………………………. 30
Chapter Four…………………………………………………………….. 31
4.0 Methodology…………………………………………………. 31
4.1 Study design………………………………………………….. 31
4.2 Study area……………………………………………………. 31
4.3 Study population…………………………………………….. 32
4.4 Materials and methods………………………………………. 32
4.5 Inclusion criteria…………………………………………….. 36
4.6 Exclusion criteria……………………………………………. 36
4.7 Limitation of the study………………………………………. 36
4.8 Data analysis………………………………………………… 37
4.9 Ethical considerations……………………………………….. 37
Chapter Five……………………………………………………………. 38
5.1 Result………………………………………………………… 38
5.2 Result analysis……………………………………………….. 38
Chapter Six…………………………………………………………….. 66
6.0 Discussion……………………………………………………. 66
6.1 The importance of immunostains in diagnosis of prostate cancer. 70
6.2 Conclusion ……………………………………………………… 72
6.3 Recommendation ……………………………………………….. 72
References………………………………………………………………….. 74
Appendix A…………………………………………………………………. 86
10
Appendix B…………………………………………………………………. 87
11
LIST OF FIGURES
Figure 1: Photo Micrograph Showing Gleason Pattern 25
Figure 2a: Showing Control Specimen for AMACR showing positive 34
Intraluminal cytoplasmic staining (adenocarcinoma well
Differentiated)
Figure 2b: Control Specimen for p63 showing positive brownish staining of 35
basal cell nuclei in Benign Prostatic Hyperplasia (BPH))
Figure 3: Pie Chart Showing Specimen Distribution 39
Figure 4: Pie Chart Showing Disease Pattern 41
Figure 5a: Photomicrograph showing mixed pattern of growth in a 50
Moderately differentiated tumour with a Gleason score
of 6/10 H&E staining (x40)
Figure 5b: Photomicrograph showing mixed pattern of growth in a 51
Moderately differentiated tumour with a Gleason score
of 6/10 AMACR staining (x40)
Figure 5c: Photomicrograph showing mixed pattern of growth in a 52
Moderately differentiated tumour with a Gleason score
of 6/10 p63 staining( x40)
Figure 6: Photo Micrograph Showing Perineural Invasion in a Poorly 53
Differentiated Tumour with a Gleason score of 10/10
H&E stain
Figure 7a: Photomicrograph showing cribriform pattern with a Gleason 54
Score of 10/10 H&E staining (x40)
Figure 7b: Photomicrograph showing cribriform pattern with a Gleason 55
Score of 10/10 AMACR staining (x40)
Figure 7c: Photomicrograph showing cribriform pattern with a Gleason 56
Score of 10/10 p63 staining (x40)
Figure 8a: Photomicrograph showing large acinar pattern with 57
Gleason Score of 2/10
Figure 8b: Photomicrograph showing large acinar pattern with 58
12
Gleason Score of 2/10 (AMACR)
Figure 8c: Photomicrograph showing large acinar pattern with 59
Gleason Score of 2/10 (p63)
Figure 9a: Photomicrograph showing a small acinar, well differentiated 60
Pattern with a Gleason score of 4/10 H&E stain
Figure 9b: Photomicrograph showing a small acinar, well differentiated 61
Pattern with a Gleason score of 4/10 AMACR stain
Figure 9c: Photomicrograph showing a small acinar, well differentiated 62
Pattern with a Gleason score of 4/10 p63 stain
Figure 10a: Photo Micrograph Showing a solid/trabecular pattern in a 63
Poorly differentiated tumour H&E staining (x40)
Figure 10b: Photo Micrograph Showing a solid/trabecular pattern in a 64
Poorly differentiated tumour AMACR staining (x40)
Figure 10c: Photo Micrograph Showing a solid/trabecular pattern in a 65
Poorly differentiated tumour p63 staining (x40)
13
LIST OF TABLES
Table 1: World Health Organisation (WHO) Classification of 18
Tumours of Prostate
Table 2: Tumour, Node and Metastasis (TNM) Classification of
19
Carcinoma of the Prostate
Table 3: Histopathological Grading 20
Table 4: Gleason Microscopic Grading System of Prostatic Carcinoma 26
Table 5: Prognostic Factors 29
Table 6: Age Distribution of Prostatic Cancers 43
Table 7: Differentiation Pattern of Prostatic Cancers 45
Table 8: Histopathologic Pattern of Prostatic Cancers Analysed 47
Table 9: Gleason Scores of Prostatic Cancers Analysed 49
14
ABSTRACT
INTRODUCTION: Worldwide, prostate cancer is the sixth most common cancer in the
world with African Americans having higher incidence. Europeans are known to have
intermediate rate while it is said to be rare in Asian populations. Recent studies have not
agreed with earlier reports which showed prostatic cancer to be rare in Africans.
Histopathologically, adenocarcinomas appear to be the predominant sub-type. The Gleason
grading which was named after Donald F Gleason, is still the predominant grading system
recommended by the consensus conference in 1993. The application of cancer over expressed
biomarkers such as AMACAR is used in conjunction with basal cell markers such as p63,
34βE12, CK5/6 , in making definitive diagnosis of prostate cancers when confronted with
difficult cases.
Objective
The study was aimed at documenting the histopathological patterns, frequency rate and age
distribution of prostate cancers in a newly established Tertiary Health Care Centre institution
over a seven (7) year period.
Materials and Method
The materials were mainly Paraffin embedded tissue blocks, histology report forms of all
prostate biopsies received in the Histopathology laboratory of the Federal Medical Centre
Keffi from January 2007 to December 2013 and records from the hospital cancer registry.
Tissue blocks were sectioned into 5µm sections, stained with standard Haematoxylin and
Eosin at the histopathology laboratory of the Jos University Teaching Hospital, while
inconclusive cases were immunostained with p63 and AMACAR at the National Hospital
Abuja, Pathology Department.
Result
Carcinoma of the prostate was diagnosed in 68 (25.9%) of prostatic tissues; constituting
44.7% of all male cancers and number one urological cancer. Five cases needed
immunohistochemistry for confirmation. All diagnosed carcinomas were adenocarcinomas
predominantly of the well differentiated and small acinar pattern with Gleason score of 2 to 4.
The age range was 20-86 years with a mean age of 64.9 years and a peak of 70 to 79 years.
Conclusion
15
The frequency of prostate cancer in Keffi is 25.9%, with 8% seen in younger age and
majority occurring in age range of 50-80. Histologically, all cases were acinar
adenocarcinomas and mostly well differentiated.
Keywords: Prostate, Cancers, Histopathological Pattern, Federal Medical
Centre Keffi.
CHAPTER ONE
1.1 INTRODUCTION
Prostatic carcinoma is an extremely common lesion in men. Worldwide,
prostatic cancer is the most common male genital cancer1 and has been
described as a public health epidemic among blacks2. It has been
reported to be the most common cancer of males, second only to lung
cancer as a cause of death in the United States of America3. The
International Agency for Research on Cancer (IARC) estimates that
cancer of the prostate is the leading cancer in terms of incidence and
mortality in men from Africa and the Caribbean4. There is limited
information about the epidemiology of cancer of the prostate in Sub-
Saharan Africa5.
IARC has estimated that cancer of the prostate is a growing problem in
Africa accounting for 28,006 deaths in 2010 and will account for
approximately 57,048 deaths by 20306 representing a rise of 104% over
16
two decades. In Zimbabwe, the prevalence has been reported to be 3.2%,
while it is 4.3% in Uganda and 4.4% in Senegal1.
It has been reported to be the number one cancer in Nigerian men
accounting for eleven percent (11%) of cancers in men despite the lack of
an organized screening programme in the country7.
The first reported series of cases of cancer of the prostate prevalence in
Nigerian men was in 1971 in Lagos. It was a retrospective study
from1962 to 1967 and a prevalence rate of 13.2% was reported 8. In 1973,
Nkponsong and Lawani reviewed all cases of prostate cancers, and found
that prostate cancers constituted 2.2% of all cancers reported9.
Researchers have reported different prevalence from different urban
centres.
In Kano, a figure of 16.5%10 has been reported as the relative frequency
of prostate cancer, In Zaria 9.2% was recorded11 while Benin and
Maiduguri have figures of 7.13%12and 6.15%13 respectively. In Calabar, a
high prevalence of 34.7% was reported, while in Jos, it is reported to be
7.9% with cancer of the prostate being the number three of all common
malignancies14,15.
In a study carried out by Dauda et al16 at the Federal Medical Centre
Gombe, North Eastern Nigeria, prostatic adenocarcinoma was found to be
17
the most common urologic malignancy representing 53.4% of all urologic
cancers seen. In Port Harcourt, Obiora and Nwosu17 reported a
prevalence of 37.4%.
The national incidence in Nigeria has been increasing with figure of
18.2%reported in some centres 18. Unquestionably, it has emerged as the
leading male cancer in Africans, African Americans and also the leading
genital cancer worldwide. It is known to occur early in blacks. The mean
age at presentation ranges from 60.5 years in Jos20, 67 years in Ibadan19 to
71 years in Zambia22. In a wide scale study in America in 1990, it was
the most commonly diagnosed cancer in American men with an estimated
220,000 new cases and 30,000 deaths annually23. It is typically a disease
of men over 50 years with incidence increasing with advancing age,
positive family history and high dietary fat; with the most consistent
finding being high level of testosterone23. Incidence increases from 20%
in the fifties to 70% between the ages of 70 and 80yrs23.
The gold standard for the diagnosis of prostatic cancer still remains the
examination of the prostatic tissues obtained by tru-cut biopsies,
transurethral resection of the prostate, radical prostatectomy or fine
needle aspirates under the microscope after processing and staining with
Heamatoxylin and Eosin (H&E) 23.
18
Prostatic cancers are histologically heterogeneous with the commonest
being adenocarcinoma with its variants. Ductal adenocarcinoma is the
second most common subtype of prostatic adenocarcinoma. Widespread
metastases (carcinomatosis) with terminal pneumonia or sepsis are the
common causes of death24.
Surgery, radiation therapy and hormonal manipulations are treatment
modalities employed with 90% of such patients living up to 15 years.
Currently, the most common treatment for localized prostatic cancer is
radical prostatectomy. The prognosis is based on the pathologic stage,
margins status and the Gleason grade.
1.1.1 HISTOLOGICAL AND IMMUNOHISTOCHEMICAL METHODS
OF DIAGNOSIS.
Histological typing and diagnosis are carried out by examining
Haemotoxylin and Eosin (H&E) stained sections. There are various types
of histological grading in use, but the most common is Gleason Grading
System .Histological diagnosis is based on architecture (pattern of
growth), absence of basal cells and nuclear atypia while the cancers are
classified based on the World Health Organization (WHO)
Classification44
19
Gleason grading/scoring is the most commonly used grading system
which uses architectural growth patterns of cellular arrangement.
Basal cell absence, the second most important criterion may be difficult
to evaluate in Haemotoxylin and Eosin stained sections. Basal cells are
therefore stained using antibodies against High Molecular Weight
Cytokeratin such as 34βE12 and also known as CK903 and p63. Positive
staining of basal cells effectively rules out invasive adenocarcinomas24.
In suspicious cases, immunostains using neoplastic cell selective marker
(alpha methylacyl co A enzyme AMACAR or p504s) is useful to assess
atypical glands, staining 80-100% of adenocarcinomas24.
Other ancillary studies using prostate specific antigen (PSA), Prostatic
Specific Acid Phosphate (PSAP), thrombomodulin and High Molecular
Weight Cytokeratin are often used to differentiate poorly differentiated
adenocarcinoma of the prostate from poorly differentiated urothelial
(transitional cell) carcinoma of the bladder24.
1.2 STATEMENT OF THE PROBLEM
1. Prostatic cancers remain the commonest malignant tumor in
Nigerian men7-21, 25-35.
2. Patients present late to clinicians and therefore lose the benefit of
early detection and possible prevention of ultimate invasive
carcinoma.
20
3. Absence of Pathologists in rural areas and lack of specialists in
Urology adds to the problem of prostatic cancer in the rural areas.
1.2.1 JUSTIFICATION FOR THE STUDY
1. A study in a tertiary health institution has become necessary, being the
first of its kind in the institution, to give an insight into the practice of
histopathology in a newly established Tertiary Health Care institution and
to see if the findings agree with those done in other tertiary health
institutions (University Teaching Hospitals).
2. The study can be used to assess the burden of prostate cancer in the area.
3. The study can serve as baseline for establishment of a screening
programme for early detection and characterization of prostate cancer.
21
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 An Overview
Prostate cancer is the most common non-cutaneous male cancer,mostly in
developed countries36. It is an emerging public health problem both
locally in Nigeria7 and Worldwide5, 15, 20-21. Racial and geographic
disparities in incidence and mortality rates have been observed2. Rural
and urban differences in incidence and mortality rates have been
reported36.
Shortages of pathologists and lack of access of the general population to
health care are among major issues confronting health care delivery in
Nigeria37.
2.2 Epidemiology
There has been increasing incidence of prostate cancer in Nigerian men
and it had become the number one cancer in 199918. In Ibadan, prostate
cancers accounted for 11% of all male cancers7. Data from other centres
such as Benin12, Calabar14, Kano10, Zaria11, Lagos14 and Maiduguri13 all
revealed an increasing incidence between 6% and 12% of total cancers
and up to 18% in other centres18.
22
Most of the patients are known to present in late stage of the disease with
attendant high mortality18. A difference in prostate cancer burden has
been attributed to several factors including quality of earlier data system,
and differences in technical manpower, infrastructure and limited access
to healthcare38. Mandong et al found it to be the commonest urological
tumour in Jos University Teaching Hospital, accounting for 44.1% of all
urological tumours in men with peak incidence of 50-60 years 21. The
peak age incidence of 50-60years is similar to what has been reported in
Lagos14, Nairobi and Zimbabwe27.
Odedina et al recently studied prostate cancer disparities in black men of
African descent39.They concluded from the growing body of literature
that the disproportionate burden of prostate cancer among men of West
African ancestry follows the path of the transatlantic slave trade and the
true prostate cancer rates reported for West Africans by World Health
Organization (WHO) may be underestimated40. Further studies may be
needed to explore the genetic and environmental risk factors for prostate
cancer among this group.
The most striking feature of prostate cancer is its ethnic disparity and
varied geographic distribution across the world which suggests the role of
inheritance and the impact of genetic risk factors on its development.
The highest prostate cancer incidence and mortality rates have been
23
reported among Black African American men living in the United States
of America and the Carribean41.
Msyamboza et al reviewed data from Malawi National Cancer Registry
established in 1985 as a population based cancer Registry, from 2007-
2010. Cancer of the prostate occupied number three (3) position
accounting for 4.0% of cancers in males. Kaposi sarcoma was found to be
the leading cancer (50.7%), followed by cancer of the oesophagus
(16.9%) and non-Hodgkin’s Lymphoma (7.8%) 42. However, Wiredu and
Armah carried out a retrospective review of autopsy records of the
Pathology Department and Medical Certificates of cause of death in
Korle-Bu Teaching Hospital, Accra, Ghana from 1991-2000 and found
out that the highest mortality in males was from liver cancer (21.2%),
followed by prostate cancer (17.4%) from 2008 cancer death in males43.
2.3 Aetiology
The cause of prostate cancer is generally unknown, but ethnic disparity in
prostate cancer incidence could suggest the role of inheritance in
oncogenesis. It is known to have a strong ethnic propensity, and it is
more common in Blacks than Whites in the United States of America
(USA). Generally, it is proposed to be a polygenic disease with alleles of
low penetrance. However, all men are at increased risk for prostate
cancer developing with advanced age. Certain risk factors are known to
24
be associated with prostate cancer. These may be grouped into proven,
probable and potential risk factors44.
2.3.1 Proven Risk Factors
These are non-modifiable. They include Age, Race, and Family History.
Prostate adenocarcinoma is uncommonly diagnosed clinically before the
age of 50, but a significant minority in their thirties (30s) and forties (40s)
have small adenocarcinoma detectable at autopsy24. African Americans
are more frequently affected than their Caucasian counterparts45. Men
with an affected father or brother are twice more likely to develop the
disease. Sternberg et al agree that a family history of prostate cancer in
the first degree relative multiplies the risk approximately two-fold46.
Familial prostate cancer implies the clustering of this disease within
families. Approximately 43% of men diagnosed with prostate cancer
before the age of 55 years have Hereditary Prostate Cancer (HPC), a
subtype of familial cancer with Mendelian pattern of inheritance47.
2.3.2 Probable Risk Factors
These include high intake of dietary fat, red meat and androgens
(testosterone) 48.
25
2.3.3 Potential Risk Factors
These include exposure to cadmium, low levels of vitamin D, vitamin E
and selenium49. Others are sedentary lifestyle and exposure to herbicides.
Lycopene (found in tomatoes) and soy products are known to prevent or
delay prostate cancer development50. In regarding diet, vitamin E,
lycopene and other carotenoids in tomato based products and selenium
are known to exert protective effects, while diets rich in fat and red meat,
especially well cooked meat exert promotional effects48-51. These dietary
factors are antioxidants. Oxidative stress with DNA damage contributes
to carcinogenesis.
Insulin like growth factor 1 (IGF-1), which can be influenced by diet or
genetics have been implicated in the development of aggressive prostate
cancer52. Prostate adenocarcinoma may arise from high grade prostatic
intra epithelial lesions53. Focal atrophy lesions which are extremely
common in prostate cancers are known to result from cellular injury
secondary to dietary and inflammatory insults54. These atrophic lesions
show morphological transition to micro carcinoma lesion55.
2.4 Pathogenesis
Prostate cancer cells contain a large number of somatic genome
alterations55-59. These alterations contribute to the cancer phenotype and
include genetic (changes in DNA sequence), such as point mutations,
26
deletions, amplifications and translocations. Other changes are epigenetic
including modifications in deoxycytidine methylation.
The major challenge for researchers is to identify the changes that are
causal and those that are bystanders unrelated to disease process. Genetic
change commonly seen is telomere shortening60, 61, while somatic
hypermethylation of deoxycytidine residues within CpG dinucleotides in
the upstream regulatory regions of a number of genes occur earlier and
more consistently in prostate cancer than recurrent genetic changes do.
2.4.1 Glutathione S-Transferase (GSTP1)
An epigenetic alteration occurs that leads to the hypermethylation of
GSTP1 gene which down regulates GSTP1 expression. GSTP1 functions
as a care-taker gene, defending prostate cells against genomic damage by
carcinogens or various oxidants. CpG island hypermethylation within
GSTP1 promoter region has been studied62; a large number of studies
have verified this finding which occurs in over 90% of prostatic cancers63-
64.
2.4.2 Somatic Genetic Alterations and Prostate Cancer
Prostate cancer shows genetic changes at the chromosomal or sub-
chromosomal level56-59. Most common are losses at 8p, 10q, 13q, 16q
and recurrent losses at rearrangement on chromosome 22q between the
27
TMPRSS2 and ERG gene loci. Recurrent genes include those at 7p, 7q
8q and Xq.
2.4.3 Tumour Suppressor Genes and Loss of Heterozygosity
Deletions of genetic sequences from sites on chromosome 8p frequently
occur in prostate cancer. Several genes located on chromosome 8p have
been examined. The mostpromising being NKX3.1.
PTEN (Phosphate and Tensin homolog) gene is mutated in 1.3 of
hormone refractory prostate cancers and homozygous deletions and
mutations have been identified in a subset of prostate cancers. Other sites
of loss/deletion in prostate cancer include genetic inactivation of tumor
suppression genes p53, RB1and p16 seen in metastatic and/or hormone
refractory lesions suggesting they may be involved in tumor progression.
Amplification of certain regions on chromosome 8q correlates with
aggressiveness of the tumor .One candidate gene for amplification on 8q
is the C-MYC oncogene23. Another gene on chromosome 8q that is often
amplified in prostate cancer is PSCA encoding stem cell antigen which is
also accompanied by demonstrable protein over expression. PSCA is a
cell surface marker and humanized antibodies or fragments are being
investigated in clinical trials in patients with metastatic prostate cancer.
Other genes on chromosome 8q recently implicated include the Elongin C
28
gene and the EIF3S3 gene. Other regions of gain include the AR gene
itself (located on Xq12), where amplification occurs almost exclusively in
the hormone refractory state23.
2.5 Oncogenes /Growth Promoting Genes
2.5.1 Androgen Receptor
Androgenic hormones and an intact Androgen Receptor (AR) are
required for normal prostatic growth and development. Androgen
Receptor is highly expressed in the luminal epithelial cells where it is
concentrated within the nuclei. Vast majority of prostatic adenocarcinoma
cells express AR at relatively high levels. This had been explored in the
treatment of metastatic prostate cancer through androgen deprivation,
anti-androgen or both.
Androgen Receptor is critical for androgen refractory prostate tumour cell
proliferation. AR expression is often increased in hormone refractory
prostate cancer. Somatic alterations or AR may occur especially for
androgen independent prostate cancers and these mutilations are often
activating mutations.
29
2.5.2 Gene Fusion
This translocation places when the coding sequence of an ETS family
transcription factor placed next to the androgen regulated TMPRSS2
promoter gene leading to the over expression to the ETS gene in an
androgen dependent fashion. Normal prostatic epithelial cells therefore
become more invasive through up regulation of metalloproteases.
2.5.3 Oncogenic Tyrosine Kinases
In prostate cancer aberrant tyrosine kinase signaling, particularly through
Her2/Neu of SRC, Tyrosine Kinases has been implicated in aggressive
disease, progression to metastasis and castration resistance.
2.5.4 EZH2 (Enhancer zest-2)
EZH2 is up-regulated in advanced prostate cancer and is associated with
aggressive tumours. Over expression of EZH2 leads to loss of E-
cadherin.
2.5.5 BRCA2
Men with germ line mutations of BRCA2 have a twenty (20) fold
increased risk of prostate cancer, though a vast majority of familial cancer
are due to variation in other loci that confer a small increase in cancer
risk. 8q24 selectively increases the risk in African American men23.
30
2.6 Pathological Features
Prostate cancer is generally regarded as a multifocal disease because
primary tumours often contain multiple independent histological foci of
cancer that are genetically distinct. However, despite phenotypic
heterogeneity, metastatic cancers are monoclonal as suggested by
molecular and cytogenic analyses.
Prostate cancer, unlike other epithelial tumours, such as breast cancer,
lack distinguishable histopathological subtypes that differs in their
prognosis or treatment response. The vast majority are acinar
adenocarcinoma that expresses androgen receptors, AR. Extremely rare
forms are signet ring carcinoma, mucinous carcinoma and ductal
adenocarcinoma.
2.6.1 Morphology
Prostate cancer is divided into two major groups. These are
adenocarcinoma of the peripheral (secondary) ducts and carcinoma of
large (primary) ducts. Majority of the tumours belong to the first group.
In approximately 70% of the cases, carcinoma of the prostate arises in the
peripheral zone posteriorly.
Grossly, the gland is firm and gritty in cutting. The cut surface is
grayish-white to yellow-orange. Studies on grading, staging, prognosis
31
and therapy of prostatic cancer relate to the adenocarcinoma group.
Studies from all regions of Nigeria, found out that adenocarcinoma are
the predominant histological type7-23, 25-35.
32
Table 1: World Health Organisation (WHO) Histological Classification
of Tumours of Prostate
2.5.1.2 Epithelial Tumours I .Glandular Neoplasm
Adenocarcinoma (7subtypes)
Atrophic, Pseudohyperplastic, Foamy, Colloid, Signet
Ring, Oncocytic
Lymphoepithelioma-like
Carcinoma with spindle cell differentiation(2 subtypes)
carcinosarcoma, sarcomatoid carcinoma
ii. Prostatic Intraepithelial Neoplasia (PIN)
Prostatic Intraepithelial Neoplasia Grade III (PIN III)
iii.Ductal Adenocarcinoma (3 subtypes)
Cribriform, Papillary, Solid
iv.Urothelial Tumours
Urothelial carcinoma
v.Squamous Tumours(2 subtypes)
Adenosquamous carcinoma, Squamous cell carcinoma
vi.Basal Cell Tumours (2 subtypes)
Basal cell adenoma, Basal cell carcinoma
2.5.1.3Neuroendocrine
Tumours
Endocrine differentiation within adenocarcinoma,
Carcinoid tumours, Small cell carcinoma,
Paraganglioma, Neuroblastoma
2.5.1.3 Prostatic stromal
tumours
Stromal tumour of uncertain malignant potential, Stromal
sarcoma
2.5.1.4 Mesenchymal
Tumours
Leiomyosarcoma, Rhabdomyosarcoma, Chondrosarcoma,
Angiosarcoma, Malignant fibrous histiocytoma,
Malignant peripheral nerve sheath tumour,
Heamangioma, Chondroma, Leiomyoma, Granular cell
tumour, Haemangiopericytoma, Solitary fibrous tumour
2.5.1.5. Haematolymphoid
tumours
Lymphoma, Leukaemia
2.5.2.1 Miscellaneous tumous Cystadenoma, Germ cell tumours, Melanoma, Clear cell
adenocarcinoma, Metastatic tumours, Tumours of
seminal vesicles, Yolk sac tumour,
Seminoma,Nephroblastoma(Wilms Tumour),
Embryonal carcinoma and teratoma
2.5.2.2 Metastatic Tumours
2.5.2.3 Tumours of the
seminal vesicles
2.5.2.4 Epithelial Tumours Adenocarcinoma, Cystadenoma
2.5.2.5 Mixed Epithlial and
Stromal Tumours
Malignant,Benign
2.5.2.6 Mesenchymal
Tumours
Leiomyosarcoma, Angiosarcoma, Malignant fibrous
histiocytoma, Liposarcoma Heamangiopericytoma,
Leiomyoma,
2.5.2.7 Miscellaneous
Tumours
Choriocarcinoma, Male adnexal tumour of probable
Wolffian origin
33
Table 2: Tumour, Node and Metastasis (TNM) Classification of
Carcinomas of the Prostate
T- Primary
Tumour
TX Primary tumour cannot be assessed
T0 No evidence of primary tumour
T1 Clinically inapparent tumour not palpable or visible by
imaging
T1a Tumour incidental histological finding in 5% or less of
tissue resected
T1b Tumour incidental histological finding in more than 5%
of tissue resected
T1c Tumour identified by needle biopsy (e.g. because of
elevated PSA)
T2 Tumour confined with prostate
T2a Tumour involves one half of one lobe or less
T2b Tumour involves more than one half of one lobe but not
both lobes
T2c Tumour involves both lobes
T3 Tumour Extends beyond the prostate 2
T3a Extra capsular extension (unilateral or bilateral)
T3b Tumour invades seminal vesicles
T4 Tumour is fixed or invades adjacent structures other than
seminal vesicles, bladder neck, external sphincter, rectum,
levator muscles or pelvic wall
Notes: 1. Tumour found in one or both lobes by needle biopsy but
not palpable or visible by imagine is classified as T1c.
2. Invasion into the prostatic apex yet not beyond the prostate
is not classified as T3 but as T2.
3. There is no pT1 category because there is insufficient
tissue to assess the highest pT category.
4. Microscopic bladder neck involvement at radical
prostatectomy should be classified as T3a
N – Regional
Lymph Nodes
NX Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Regional lymph node metastasis
Note: Metastasis larger than 0.2cm can be designated pN1mi
M – Distant
Metastasis
MX Distant metastasis cannot be assessed
M0 No distant metastasis
M1 Distant metastasis
M1a non-regional node(s)
M1b Bone(s)
M1c Other site(s)
34
Table 3: Histopathological Grading
G
Histopathological
Grading
GX Grade cannot be assessed
G1 Well differentiated (Gleason 2-4)
G2 Moderately differentiated (gleason 5-6)
G3-4 Poorly differentiated/undifferentiated (Gleason
7-10)
Stage Grouping Stage I T1a N0 M0 G1
Stage II T1a N0 M0 G2, 3-4
T1b,c N0 M0 any G
T1, T2 N0 M0 any G
Stage III T3 N0 M0 any G
Stage IV T4 N0 M0 any G
Any T N1 M0 any G
Any T any N M1 any G
35
2.7 Criteria for Histological Diagnosis
Microscopy remains the most important tool in the diagnosis of
urological carcinoma of the prostate and is based on the examination of
H&E stained sections.
2.7.1 Major Criteria
Architectural: Infiltrative small glands of cribriform glands too large or
irregular to represent high grade PIN
Cells in a single layer (absence of basal cells)
Nuclear atypia: Nuclear or nucleolar enlargement
2.7.2 Minor Criteria
Intraluminal wispy blue mucin (basophilic mucinous secretions)
Pink amorphous secretions
Intraluminal high grade PIN
Amphorphilic cytoplasm
2.8 Clinical Presentation
Reports from all regions of Nigeria emphasize late presentation. In a
study by Badmus et al65, about two-thirds of the patients presented with
metastatic disease and 94.25% presented with complications. Mortality is
very high with 64% deaths within two years in a review by Osegbe66.
36
Metastasis is typically to the spine with paraparesis or paraplegia. Rare
orbital metastases were reported inIbadan67.
There is growing concern that medical students do not gain enough
knowledge in digital rectal examination such that clinical diagnosis of
cancer of the prostate becomes a dilemma for the young doctor. Even
when such skills are adequately acquired, they are often not translated
into clinical practice68.
There is lack of awareness for prostate cancer screening among
Nigerians. Knowledge and risk perception are low69. A study in Burkina
Faso by Kabore et al also found adenocarcinoma to be the most common
histological type of prostate cancer with Gleason score of 7-10 or clinical
stage T3-T4. They also found that prostate cancer is diagnosed at later
stages in Burkina Faso with very high serum Prostate Specific Antigen
(PSA) and poorly differentiated tumours70.
2.9 Diagnosis
Three parameters used for screening and early detection of prostate
cancer are digital rectal examination, transrectal ultrasonography and
serum Prostate Specific Antigen (PSA). However, there is limited data
on prostate cancer screening in Africa. This was reported in a study by
Jalloh et al71, which found out that PSA screening is not widely used on
37
Senegalese men. They also found out that the likelihood of having
abnormal PSA increases with age and abnormal digital rectal finding
readings.
Age and race specific ranges, free and total PSA ratio and PSA velocity
are the indices used. The ratio of free to total PSA decreased in cancer of
the prostate, the lower the ratio, the greater the possibility of prostate
cancer. The rate of change in total PSA levels over time is referred to as
PSA velocity and a value of 0.75µg/L per year is suspicious of prostate
cancer even if PSA is in the normal range. Equally, the ratio of serum
PSA to the volume of prostate gland measured by transrectal ultrasound
is referred to as the PSA density. Volume ≥0.1 ng/ml/cm3is considered
pathological.
Value of routine screening has been challenged as it does not
significantly affect overall mortality from cancer of the prostate.
2.10 Tissue Diagnosis
Tissues are obtained by transrectal core biopsies (using the sextant
protocol from the apex, mid and base regions), extended ten core biopsy
protocol, transurethral resection of the prostate, transrectal, FNAC or
from radical prostatectomy.
38
2.10.1 Histochemical and Immunohistochemical Features
Immunohistochemistry with 34βE12 (CK903) and p63 are very valuable
adjunctive diagnostic tools. The p63 stains a subset of 34βE12 negative
basal cells and it is easier to interpret due to its strong nuclear intensity.
AMACAR (P504S) is used as a positive confirmation. It is
overexpressed in prostate cancer. It is often used as confirmatory stain
for cancer of the prostate in conjunction with H&E morphology and basal
cell specific marker (CK903).
2.11 Histological Grading
Grading is performed using the Gleason grading system which is the most
reliable parameter used in predicting prognosis in patients with prostatic
cancer. All adencarcinoma of the prostate should be graded. Grading is
solely based on the architecture of the glands at low magnifications (4-
10x). The most common pattern and the second most common pattern
are summed up to yield a score on a scale of 2 to 10.
39
Fig 1: Photo Micrograph Showing Gleason’s Pattern
This illustration shows Dr Gleason's own simplified drawing of the five Gleason
grades of prostate cancer. Grade 1 appears on the far left and grade 5 on the far
right.
40
Table 4: Gleason Microscopic Grading System of Prostatic Carcinoma73
Stage Description
1 Single, separate uniform glands in closely packed masses with a definite
usually rounded edge limiting the area of tumour
2 Single, separate slightly less uniform glands loosedly packed (separated
by small amounts of stroma) with less sharp edge
3a Single, separate much more variable glands: may be closely packed but
usually irregularly separated, ragged poorly defined edge
3b Like 3a, but very small glands or tiny cell clusters
3c Sharply and smoothly circumscribed rounded masses of papillary or
loose cribriform tumour(papillary intraductal tumour)
4a Raggedly outlined, raggedly infiltrating, fused glandular tumour
4b Like 4a, with large pale cells (hypernephroid)
5a Sharply circumscribed, rounded masses of almost solid cribriform
tumour, usually with central necrosis (comedocarcinoma)
5b Ragged mass of anaplastic carcinoma with only enough gland formation
vacuoles to identify it as adenocarcinoma
41
2.11.2 2005 ISUP Modified Gleason System
The International Society of Urological Pathologists in 2005, made some
modifications to the Gleason system. Changes to pattern 3 and 4 were
made.
The definition of pattern 3 was limited and that of pattern 4 widened. In
this, individual cells would not be allowed in pattern 3, while large,
cribriform glands with rounded smooth contours originally diagnosed as
pattern 3 are to be diagnosed as pattern 4. Pattern 4 which originally was
limited to fuse or irregularly contoured cribriform structure has been
widened in scope to include almost all cribriform morphorlogy.
Pattern 3is defined as glands with poorly formed lumina, a pattern which
often is accompanied by fused glands warrants a diagnosis of Gleason
pattern 4. Glomerulations (dilated glands containing intraluminal
cribriform structures with a single point of attachment, resembling
glomerulus) are accepted in pattern 4.
However, Lotan et al, in a recent study, concluded that biopsies
containing glomeruloid features were overwhelmingly associated with
high grade cancer on the same score composed predominantly of Gleason
pattern 4. They recommended that all cribriform patterns be diagnosed as
Gleason pattern 473.
42
2.12Prognosis
The prognosis varies widely with tumour grade and stage. The grade and
stage correlates well with each other and with prognosis. Several
parameters have been evaluated for their ability to predict outcome in
patients with prostatic carcinoma. They are grouped into three74.
43
Table 5: Prognostic Factors
CATEGORY I Proven to Be of Prognostic Importance and Useful Clinical
Patient Management.
Preoperative Serum PSA Level.
TNM Stage Grouping.
Histologic Grades as Gleason Score
Surgical Margin.
CATEGORY II Extensively Studied But Whose Importance Remains to Be
Evaluated.
Tumour Volume.
Histological Type.
DNA Ploidy.
CATEGORY III Not Sufficiently Studied to Demonstrate Their Prognostics.
Perineural Invasion.
Neuroendocrine Differentiation.
Micro Vessel Density.
Nuclear Roundness.
Chromatin Texture.
Other Karyometric Factors.
PSA Derivatives.
Other Factors Like Oncogenes, Tumour Suppressor Genes
etc.
44
CHAPTER THREE
3.0 Aims and Objectives
3.1 General Objectives
The general aim of this study is to determine the pattern and age
distribution of cancer of the prostate seen in a tertiary health care
institution, located in a rural area.
3.2 Specific Objectives
3.2.1 To characterize prostate cancers seen using Gleason grading system of
adenocarcinomas.
3.2.2 To confirm the diagnosis using immunohistological stains in inconclusive
cases.
45
CHAPTER FOUR
Methodology
4.1 Study Design
This is a retrospective study of prostatic caners diagnosed at the Federal
Medical Centre, Keffi, Nasarawa State between 2007 and 2013. It is a
hospital based study which involved analysis of paraffin embedded tissue
blocks and slides of prostatic tissues received in the histopathology
laboratory of the hospital. Immunohistological stains were used for
additional information for inconclusive cases.
4.2 Study Area
Federal Medical Centre Keffi is located in Keffi, in Nasarawa State.
Nasarawa State in located in the North Central part of Nigeria. It is
bounded to the north by Kaduna State, in the west by the FCT, in the
south by Kogi and Benue States and in the east by Plateau and Taraba
States. Nasarawa State has a population of over two million (2,040,094)
while Keffi has a population of approximately 85,000 (estimates from
2006 national census). The area has two seasons each year and an annual
rainfall of 1000mm to 2000mm, July and August being the most wettest
months and November to April being the hottest. Annual temperature
ranges from 20-34oC (degrees centigrade). The area fall within the
southern guinea savannah zone with dense forest found in the lower
land.The southern part is formed by the plains of Benue valley. Federal
46
Medical Centre Keffi Histopathology Laboratory receives specimen from
hospitals in Nasarawa State, Parts of Southern Kaduna State and the
Federal Capital Territory, Abuja.
4.3 Study Population
This is a hospitalbased analysis of histology specimens at
theHistopathology Department of the Federal Medical Center, Keffi, in
Nasarawa State. The population includes therefore, all prostatic tissues
received at the Histopathology Department of the Federal Medical
Centre, Keffi. This is the first and only hospital in Nasarawa State that
has a functional histopathology laboratory. The target population was
therefore men with histologically diagnosed prostate cancers.
4.4 Materials and Methods
Stored paraffin embedded tissue blocks were used. These were sectioned
into 5µm section and stained with Haematoxylin and Eosin by the
Department of Pathology, Jos University Teaching Hospital (JUTH) and
examined under amicroscope. Histologically confirmed prostatic cancers
were graded using the Gleason scoring system (Fig 1, Table 1). A
primary grade was assigned to the dominant pattern and a secondary
grade was assigned to the second most frequent pattern. If three patterns
are present, the most common and the highest grades were added together
47
to arrive at the Gleason score. They were then scored over 5 and the total
added to give the Gleason score over 10.
In inconclusive cases, immunohistochemical stains were used for
confirmation. This was carried out at the National Hospital Abuja.
Prostate marker (alpha-methlacyl co-enzyme A-racemes (AMACAR)
produced by Biogenex was used to confirm adenocarcinomas.
AMACAR was scored as negative (non-staining), 1+ (weak- faint
cytoplasmic, <10%), granular apical staining 2+ (10-50% of cells
stained), 3+ (>50% diffuse intense cytoplasmic staining) (Fig 2A).
Basal cell marker p63produced by Novocastra/Leica which stains nucleus
was used to stain the basal cells. Basal cell markers were scored as
strong, moderate, weak or negative. It was considered complete if >75%
of the circumference of the gland is positive and partial if <25% are
positive. Non-staining of the basal cells/myoepithelial cell is indicative of
carcinoma (Fig 2B). The immunohistochemical staining was carried out
at the National Hospital Abuja with commercially prepared antibodies
from Biogenex clone no 13H4 Isotype IgG (source is rabbit) for
AMACAR and Mouse Monoclonal produced by Novocastra/Leica clone
no NCL-p63 for p63. The technique used was the novolink polymer
detection system (Leica Products) following the protocol adopted by the
hospital (Appendix A).
48
Fig 2a: Control specimen for AMACAR showing positive
intraluminal apical brownish cytoplasmic staining (adenocarcinoma
well differentiated)
49
Fig 2b: Control specimen for p63 showing positive brownish staining of
basal cells nuclei in benign prostatic hyperplasia (BPH))
50
4.5 Inclusion Criteria
All prostate biopsies received over the period of study were included in
the study as some cases might have been misdiagnosed as benign
hyperplasia and needed to be reviewed. All histologically confirmed
adenocarcinoma were graded, scored, immunostained and included in the
study.
4.6 Exclusion Criteria
All specimens that were inadequate and had insufficient bio-data were
excluded from the study. All cases that the tissue blocks could not be
traced were equally excluded from the study.
4.7 Limitation of the Study
Availability of funds and necessary facilities to carry out required all
immunohistochemical staining limited the study. Immunohistochemical
staining was therefore, restricted to only AMACAR and p63.
Difficulty in extracting old slides and tissue blocks, non-dependable
archiving practice in the laboratory thereby constituting loss of tissue
blocks, early disposal of tissues making it difficult to revisit and where
tissue blocks are missing. Also, poor tissue preparation by technical staff
resulting in poor quality slides. Inadequate biodata was also a constrain in
the study.
51
4.8 Data Analysis
Data is displayed in tabular form. Charts such as bar and pie charts are
used to display data. The data was subjected to Chi-square and
percentages were calculated. EPI Info©Software version 7(Center for
Disease Control, USA) was used to analyze the data obtained.
4.9 Ethical Consideration
The study wasconducted after obtaining ethical clearance from the
Federal Medical Center, Keffi (Appendix B).
52
CHAPTER FIVE
5.1 RESULT
5.2 Result Analysis
During the period January2007to December 2013, a total of three
thousand nine hundred and ninety one (3991) biopsied specimens were
received at the Histopathology laboratory of the Federal Medical Centre
Keffi. Two Hundred and Sixty four 264 representing6.6% were prostate
biopsies comprising tru-cut and prostatectomy specimens. One hundred
and fifty two (152) male cancers were diagnosed during the period under
study. Prostate cancer was the number one cancer accounting for sixty
eightcases (44.7%) followed by skin cancers, 30cases (19.7%), and
connective tissue tumors 11 cases (7.2%) Other Urological tumors, 8
cases (5.3%).Other cancersconstituted 28.4%. A total of two hundred and
thirty prostatic tissues blocksaccounting for 87.1 % of all prostatic
biopsies were recovered and analyzed.
53
Fig 3: Pie Chart Showing Specimen Distribution during the Study Period
in the Histopathology Laboratory of Federal Medical Centre, Keffi
54
During the same period under study 63 cases of cancer (25.4%) of
prostatic tissues i.e 1.7% all biopsied specimen were histologically
diagnosed as prostate cancers.Further review of all the prostatic tissues
yielded additional five (5) cases of cancers (7.4%) making a total number
of 68 cases.
55
Fig 4: Pie Chart Showing Disease Pattern of the Prostatic Specimen
seen in Federal Medical Centre, Keffi
56
A total of 68 cases of prostatic cancers were therefore diagnosed
accounting for (25.9%) of all prostatic tissues.
Thirty nine (39) of these casesmet the inclusion criteria (57.4%) the
remaining 29 (42.6%) were excluded from the study having met the
exclusion criteria.
The age range of the patients was 20 to 86 years with a mean age of 64.9
years and a peak age group of 70-79 years. Forty (40%) percent of the
cases occurred in the peak age group; while 89.8% of the case were
discovered within the age groupof 50 to 80 years. The remaining 10 (25
%) were found within the age range of 20 to 49 years age group (table 6).
57
Table 6: Age Distribution
of prostatic cancers.
Age
Range
Frequenc
y
Percentag
e
<40 3 8%
40 – 49 0 0%
50 – 59 7 18%
60 – 69 9 23%
70 – 79 16 41%
80 – 89 4 10%
Total 39 100%
58
All prostatic cancers were adenocarcinomas. Out of these, 17 cases
(43.6%) were well differentiated, 11 cases (28.2%) were moderately
differentiated while 11 (28.2%) were poorly differentiated (Table 7).
59
Table 7: Differentiation Pattern of
prostatic cancers.
DIFFRENTI
ATION
Freque
ncy
Perce
nt
Well
Differentiated 17
43.6
%
Moderately
Differentiated 11
28.2
%
Poorly
Differentiated 11
28.2
%
Total 39 100.0
0%
60
Thirteen cases (33.3%) were histologically of small acinar pattern while
11 (28.2%) were of large acinar cribriform pattern were 5 (12.3%) and
solid trabacular constituted 10 (25.6 %) (Table 8)
61
Table 8: Histopathologic Patterns
of prostatic cancers analysed.
HISTOLOGIC
PATTERN
Frequ
ency
Perc
ent
Cribriform 5 12.8
%
Large Acinar 11 28.2
%
Small Acinar 13 33.3
%
Solid Pattern 5 12.8
%
Trabacular 5 12.8
%
Total 39 100.0
0%
62
Gleason grading and scoring of the adenocarcinomas shows that scores 2 to 4
constituted 17 cases (43.6%), those with 5 to 6 were 11 (28.2%) while those
with scores 7 to 10 constituted 11 cases (28.2%). The highest single Gleason
score was 4 with cases of which 7 (77.8%) presented as 1 +3 (Table 9).
63
Table 9: Gleason Scores of prostatic cancers analysed.
GLEASONSCORE Frequency Percent
2 5 12.8%
3 3 7.7%
4 9 23.1%
5 2 5.1%
6 8 20.5%
7 3 7.7%
8 5 12.8%
10 4 10.3%
Total 39 100.00%
64
Fig 5a: Photo Micrograph Showing a Mixed Pattern of growth in a
moderately Differentiated Tumour with a Gleason score of 6/10 H&E
Staining x40
65
Fig 5b:Photo Micrograph Showing a Mixed Pattern of growth in a
moderately Differentiated Tumour with a Gleason score of 6/10 AMACR
Staining X40 (note the brownish cytoplasmic stains)
66
Fig 5c: Photo Micrograph Showing a Mixed Pattern of growth in a
moderately Differentiated Tumour with a Gleason score of 6/10 p63
Staining X40 (note lack of staining in basal cells)
67
Fig 6: Photo Micrograph Showing Perineural Invasion in a Poorly
Differentiated Tumour (note tumour cells surrounding nerve bundle-
arrow) with a Gleason Score of 10/10 H & E Stain
68
Fig 7a: Photo Micrograph Showing Cribriform Pattern with a Gleason
score of 10/10 H&E Staining X40
69
Fig 7b: Photo Micrograph Showing Cribriform Pattern with a Gleason
score of 10/10 AMACR Staining X40 (note brownish, diffuse granular
cytoplasmic stain with pleomorphic nuclei and prominent nucleoli)
70
Fig 7c: Photo Micrograph Showing Cribriform Pattern with a Gleason
score of 10/10 p63 Staining X40 (note lack of basal cell staining)
71
Fig 8a: Photo Micrograph Showing Large Acinar Pattern with a Gleason
score of 2/10
72
Fig 8b: Photo Micrograph Showing Large Acinar Pattern with a Gleason
score of 2/10 showing luminal apical cytoplasmic staining (AMACR)
73
Fig 8c: Photo Micrograph Showing Large Acinar Pattern with a Gleason
score of 2/10 showing lack of staining of basal cells (p63)
74
Fig 9a: Photo Micrograph Showing a Small Acinar Well, Differentiated
Pattern With a Gleason Score of 4/10 H&E Stain
75
Fig 9b: Photo Micrograph Showing a Small Acinar Well Differentiated
Pattern With a Gleason Score of 4/10 AMACR Staining
76
Fig 9c: Photo Micrograph Showing a Small Acinar Well, Differentiated
Pattern With a Gleason Score of 4/10 p63 Staining
77
Fig 10a: Photomicrograph Showing a Solid/Trabecular Pattern in a Poorly
Differentiated Tumour H&E Staining X40
78
Fig 10b: Photomicrograph Showing a Solid/Trabecular Pattern in a Poorly
Differentiated Tumour AMACR Staining X40
79
Fig 10c: Photomicrograph Showing a Solid/Trabecular Pattern in a Poorly
Differentiated Tumour p63 Staining X40
80
CHAPTER SIX
6.0 DISCUSSION
This seven year retrospective study showed that a total of three thousand
nine hundred and ninety one biopsied specimens were received in the
Histopathology laboratory.Two hundred and sixty four were prostatic
biopsies comprising tru-cut and prostatectomy specimens.
One hundred and fifty two (152) male cancers of various types and 325
female cancers were diagnosed, giving a total of 477 cancer cases (both
male and female). The number one female cancer was cancer of the
uterine cervix (83 cases) followed by breast cancer (79 cases).
Sixty eight of the cancers diagnosed in male were prostate cancers. This
accounted for 44% of all male cancers, 25.9% of all prostatic biopsies and
14.3% of all cancers recorded. This was followed by skin cancers,
30cases (19.7%), connective tissue cancers were 11 cases (7%) while
other urological cancers accounted for 8 cases (5%). Other male cancers
constituted 28.4%.This finding is consistent with recent previous reports
from other regions of the country that prostate cancer is generally
common and is the number one non cutaneous cancer in men in Nigeria
and Africa with increasing incidence7-20, 31, 34, 65, 75, 76, 79.This study also
showed that prostate cancer is the number one male cancer in this locality
though it may not agree with findings in Asia,the Middle Eastandsome
parts of Africa1, 80, 81,82,84,86.
81
Age, race and family history are well known non-modifiable risk factors
for prostate cancer23.The age range was 20 to 80years with a mean age of
64.9years and a peak age of 70-79 years. Eight percent (8%) were
observed in forty years and below. Several studies have found prostate
cancers in younger age in Africans 13, 24,35,76,79.There are also reports of
rarity of prostate cancer below the age of forty years, these include
studies by Akang et al in Benin12,Obiorah and Nwosu in Port Harcourt17,
Annunobi et al in Lagos75, Dawam et al in Zaria35.
High grade Prostatic Intraepithelial Lesion is a well-known precursor
lesion for prostate cancer. In this study, all cases of high grade PIN were
seen with adenocarcinoma. This study did not record high grade PIN in
benign prostatic lesion.
In this study the mean age was 64.9 and peak group was 70-79 with 40%
of cases.Most of the cancers were seen in the age group of 50-80years
conforming with literature reports23, 24, 80, 81.82.
All cancers found were adenocarcinoma which agrees with other centers
in Nigeria5-24, 26-33.These were from tru-cut and prostatectomy specimens.
Five (5) cases (7.4%) were incidental cancers. These were incidental
findings during re-evaluation of all prostatic specimens. Different rates of
incidental cancers have been reported from different regions of Nigeria.
Obiorah and Nwosu reported17.2% in Port Harcourt17,Dawam et al
10%in Zaria35,Mohammed et al12.3% in Jos32. This may be due to
82
surgical practices in the respective hospitals as these were hospital based
studies; also, there are no established screening programs for prostate
cancers.
Perineural invasion which is regarded as pathognomonic of prostate
cancer was recorded in 10% of the cases 91.
Forty three percent of the Adenocarcinomas were well differentiated in
this study. Similar findings have been reported in Jos20, Benin28 and
Kano10.Separate studies have reported different findings, these include
studies by Dawam et al35in Zaria, Annunobi et al in Lagos75 and other
parts of Nigeria and Africa8,70 wherepoorly differentiated cancers were
predominant.The study inPort Harcourtby Obiorah and Nwosu reported
thatmoderately differentiated (62.1%) cancers constituted majority of
cases, 16.7% were well differentiated and12.1% were poorly
differentiated17.
The histological pattern of the adenocarcinomas showed a predominance
of the small acinar (33.33%) variety followed by large acinar (28.21%),
cribriform pattern (12.8%) and solid /trabecular pattern (25.6%). Similar
pattern was reported in a study in Benin79 which revealed a large
proportion of small acinar pattern (40.6%), and the study in Port
Harcourt17 which also showed the histological growth pattern to be
predominantly small acinar pattern (33.3%), followed by large acinar
pattern (28.2%) and solid/trabecular (25.6%) and cribriform (12.8%). In a
83
study by Monika et al80 in India, the predominant histological patterns
were categorized as primary, secondary or tertiary. They reported that
the angulated glandular pattern was the most common pattern (61.6%)
followed by fused glandular pattern (32.8%), cribriform pattern (30.1%)
sheeting (solid) pattern (23.3%), hypernephroid pattern (20.6%) necrosis
(12.3%) and single separate uniform glandular pattern (5.5%) .It therefore
showed that the predominant histological pattern of prostate cancer
growth is the acinar pattern.
Histological grade of prostatic carcinomas has been recognized as one of
the most powerful, if not dominant predictor of the clinical outcome for
patients with this cancer92. Gleason grading of the carcinomas showed
that majority of the cases had Gleason score 2-4 (43%) with 4 as the peak
which represent low grade carcinomas. 30.8% of the cases had Gleason
score 7-10 representing high grade carcinomas9.This is similar to studies
in some centres in Nigeria and Africa22, 79.However, studies from
different centres in Nigeria, Africa and other parts of the world showed
most cancers to be of high grade,with late presentation and increased
morbidity and mortality3-8, 17-19, 39,80,81,82,84,86,89.
Increasing Gleason grade is directly related to a number of
histopathological end points including lymphovascular space invasion by
carcinoma, tumour size, positive surgical margins, and pathological stage
including risk of extraprostatic extension and metastasis93, 94, 95,
96.Applying the study by Freeman and Roase85, it can be inferred that the
84
majority of the cases (43%) with scores 2 -4 are low grade and have good
prognosis.This is not absolutely true as patients with low grade
carcinomasare still at risk for having spread outside the prostate while not
all patients with high grade carcinoma component will have carcinoma
extension beyond the confines of prostatic gland92.
The possible reason for thehistopathological profile seen in most of the
cases could be attributed to low life expectancy in the population, genetic
factors, hereditary factors, environmental factors and possibly dietary
factors.This trend cannot be attributed to improved medical practice as
this is a new institution serving the population without any established
screening program for prostate cancer.
6.1 The Importance of Immunostains in Diagnosis of Prostate Cancer
Immunohistochemical study plays an important role in the diagnosis of
prostatic lesions and helps to differentiate malignant glands from benign
lesions especially for suspicious cases. The panel for the study includes
one basal cell marker such as p63, HMWCK,34βE12, cytokeratin 5/6 and
Prostate Cancer Specific Marker AMACAR. Several pseudoneoplastic
mimics of prostate cancer have been identified.Ductal carcinoma of the
prostate has been shown to have a different immunophynotype from high
grade acinar cancer which emphasizes the biological peculiarities of
ductal carcinoma87.
85
The primary uses of immunostains are to differentiate prostate cancers
from lesions that may mimic it such as atypical adenomatous hyperplasia,
crowded glands, basal cell hyperplasia, clear cell cribriform hyperplasia
and other lesions such as urothelial carcinoma88-90.
In this study p63, a basal cell marker was used to stain the basal cells.It
showed intact circumferential staining of the basal cells in all benign
prostatic lesions but showed negative staining in malignant cases.
AMACAR showed a brownish to dark diffuse cytoplasmic staining and
circumferential apical granular staining in malignant lesions.
Immunohistochemical stains (AMACAR and p63) were done on seventy
(70) cases in this study which included atypical or suspicious cases and
histologically confirmed carcinoma cases. Lack of fundswas a factor that
limited the staining of all thetwo hundred and thirty (230) prostatic tissue
biopsies that were analyzed.p63 positive staining was observed in all non-
malignant lesions which included atypical adenomatous hyperplasia (10
cases),1 case of nodular hyperplasia with infarction and squamous
metaplasiaand two(2) cases of atrophic lesions.
Positivity for AMACAR was seen in all cases of prostatic
adenocarcinoma (100%). Cases of benign prostatic lesions did not show
AMACAR positivity, also p63 was completely negative in cases of
prostatic cancers.A similar study by Monika et al80 and Jiang et
86
al98reported 100% positivity for AMACAR in prostatic cancers while
basal cell markers were completely negative.
Five (5) suspicious cases had their diagnosis changed from non-
neoplastic to neoplastic lesions based on immunohistochemical staining
with both markers (p63 and AMACAR).These were the incidental
cancers. Immunostaining with both markers helped in resolving cases
with suspicious or atypical lesions.
6.2 Conclusion
The frequency rate of prostate cancers in Keffi Federal Medical Centre
was found to be 25.8%.This is a hospital based rate. Most prostate
cancers were clustered around the age group of 50-80 years. The lowest
age recorded was 20 years with 8% of the cases occurring below the age
of 40years.Histologically, all cases were acinar adenocarcinomas and
most were well differentiated with Gleason score of 2-4.
Immunohistochemistry played an important role in the diagnosis of
prostatic lesions and helped in differentiating malignant lesions from
benign lesions especially in inclusive cases in routine histopathological
study.
6.3 Recommendations
There is need to improve the services in the laboratory. Effort should be
made to improve diagnostic, staffing and management capabilities. There
is urgent need for expansion and separation of laboratory complex into
87
different departments as lack of space has led to early disposal of tissue
blocks and biopsy specimens, making revisiting of such tissues
impossible. There is need for screening programme in the hospital by
PSA assays and ultrasound guided biopsies to ensure an early diagnosis
and improve treatment.
88
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