Prof. Dr. Pratiwi TS

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Prof. Dr. Pratiwi TS

Veterinary oncology

04/22/2023

What kind of cancer


Cancerous cells divide repeatedly out of control even though they are not needed, they crowd out other normal cells and function abnormally.

They can also destroy the correct functioning of major organs.

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What is cancer?


Cancer is a group of neoplastic diseases in which there is a transformation of normal body cells into malignant ones.

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Some basic terminology:

Oncogenesis = process of initiation of tumors (cancer) in an organism (onkos = mass; genesis = birth)

Tumor = tissue composed of cells that deviate from normal program of cell division and differentiation.

Benign tumor = tumor cells remain together in a single mass and do not invade or disrupt surrounding tissues


Some basic terminology:

Malignant tumor = tumor cells invade and disrupt surrounding tissues (diagnosed as cancer, and such cells can transform other cells to the cancerous state).

Metastasis = spread of malignant tumor cells throughout the body (typically through the blood and lymphatic system)


What causes cancer?


Cancer arises from the mutation of a normal gene.

Mutated genes that cause cancer are called oncogenes.

It is thought that several mutations need to occur to give rise to cancer

Cells that are old or not functioning properly normally self destruct and are replaced by new cells.

However, cancerous cells do not self destruct and continue to divide rapidly producing millions of new cancerous cells.

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A factor which brings about a mutation is called a mutagen.

A mutagen is mutagenic.Any agent that causes cancer is called a carcinogen and is described as carcinogenic.

So some mutagens are carcinogenic.

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What causes neoplasms (1)?

All neoplasms, whether benign or malignant (cancer) are caused by mutation of critical genes that control cell growth, maturation and organization

Mutation is irreversible, cell-to-cell inherited gene dysfunction

Exposure to certain viruses, excessive radiation, and some chemicals can cause mutation

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What causes neoplasms (2)?There are many inherited factors which

increase the risk of developing neoplasmsMutated, inherited genesGenes linked to phenotypePatterns of metabolismSensitivity to environmental exposuresMale/female genderIncreasing ageConcurrent diseases (immunosuppression)


Carcinogens


Ionising radiation – X Rays, UV light

Chemicals – tar from cigarettes

Virus infection – papilloma virus can be responsible for cervical cancer.

Hereditary predisposition – Some families are more susceptible to getting certain cancers. Remember you can’t inherit cancer its just that you maybe more susceptible to getting it.

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Benign or malignant?

Benign tumours do not spread from their site of origin, but can crowd out (squash) surrounding cells eg brain tumour, warts.

Malignant tumours can spread from the original site and cause secondary tumours. This is called metastasis. They interfere with neighbouring cells and can block blood vessels, the gut, glands, lungs etc.


Benign or malignant?

Why are secondary tumours so bad?

Both types of tumour can tire the body out as they both need a huge amount of nutrients to sustain the rapid growth and division of the cells.


Normal cell cycle is controlled by signal transduction:

• Growth factors bind to surface receptors on the cell; transmembrane proteins relay signals into the cell.

• Two types of growth factors:

1. Growth factors stimulate cell division.

2. Growth-inhibiting factors inhibit cell division.

• Healthy cells divide only when growth factor and growth-inhibiting factor balance favors cell division.

• Cancer cells divide without constraint

• So cancer is caused by mutations in growth and growth-inhibiting factor genes.


Oncogenesis arises from:

1. Spontaneous gene or chromosome mutations.

2. Exposure to mutagens or radiation.

3. Activity of genes introduced by tumor viruses.

4. Some cancers are inherited (individuals may be predisposed).



Cell cycle and cancer:

Cell differentiation occurs as cells proliferate to form tissues.

• Cell differentiation correlates with loss of ability to proliferate; highly specialized cells are terminally differentiated.

• Terminally differentiated cells have a finite life span, and are replaced with new cells produced from stem cells.

• Stem cells are capable of self-renewal; cells divide without undergoing terminal differentiation.


Tumors, neoplasms, cancer


Tumor – literally a swelling, but common term for a neoplasm

Neoplasm – ‘new cells’; a mass of tissue derived from normal tissue that grows without normal regulation of growth

Cancer – ‘The Crab’; a malignant neoplasm that grows by infiltration and which may spread to distant sites

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Oncogenesis arises from:

1. Spontaneous gene or chromosome mutations.

2. Exposure to mutagens or radiation.

3. Activity of genes introduced by tumor viruses.




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Cancer StatisticsCancer is the major cause of death in pets

greater than 10 years old45% of all dogs older than 10 years of age

die of cancer23% of all dogs die of cancer

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Feline Cancer FactsLymphoma is the most frequently

diagnosed tumor in catsSpaying female cats decreases the incidence

of lymphoma by 40-50%


Canine Cancer FactsSkin cancers are the most frequently

diagnosed tumors of dogs.Mastocytomas account for 23%

Mammary tumors are the most common tumors in female dogs.Spaying a dog prior to her first heat cycle will

decrease the risk of developing mammary cancer by 7-fold.


Breed predispositions in purebred dogs to cancer

Brachycephalic breeds (Boston Terriers, Boxers, Bulldogs, Mastiffs) – primary brain tumors

Golden Retrievers – malignant lymphoma, hemangiosarcoma

German Shepherds – hemangiosarcoma

Giant breeds – appendicular osteosarcoma

Scottish breed terriers – transitional cell carcinoma of urinary bladder


Therapies for malignancies in dogsSurgery is the primary modality for therapy of all canine tumors

Chemotherapy is used to treat canine malignant lymphoma (about 25% of cases receive multiagent therapy)

Radiation therapy is effective for some tumors

Combination therapy is common


Surgery-IndicationsMammary tumors (except

inflammatory mammary cancer)Prostate tumorsOropharyngeal tumorsSkin cancersGI tumorsLung tumorsBone tumors


Methods of TreatmentSurgeryRadiation therapyChemotherapyHyperthermiaPhotodynamic therapyOthers

Gene therapyAnti-angiogenic drugsImmunotherapyAlternative therapies


Multicentric melanoma – Arabian Horse



How is cancer detected?The owner is the first person to know if a

neoplasm is developing!Changes in normal routine (loss of appetite, for

example) (convulsions)Detection of a growth (skin tumors are very

common)Persistent illness accompanied by discharges

(vomiting, diarrhea, blood in urine are examples)Weight gain, weight loss (in a relatively short

time)



Therapies for malignancies in dogs

Surgery is the primary modality for therapy of all canine tumors

Chemotherapy is used to treat canine malignant lymphoma (about 25% of cases receive multiagent therapy)

Radiation therapy is effective for some tumors

Combination therapy is common


Radiation


BiopsyExcisional

Complete removal of the tumor

Feasible if mass is < 3 cm in diameter and freely moveable

Lymph nodes, small cutaneous nodules, mammary gland and CNS tumors, and tumors found during exploratory surgeries

NonexcisionalRemoval of only a

portion of the tumorCytology from a

fine-needle aspirate, brush samples, or impression smears or effusions

Histopathology of cutting forcep biopsies, cutting needle biopsies, punch biopsies, and incisional biopsies


AVMA’s Signs of CancerAbnormal swelling that persists or cont. to

growSores that do not healUnexplained weight lossLoss of appetiteBleeding or discharge from any body openingBad odor, especially from the mouthDifficulty eating or swallowingReluctance to exercise or loss of staminaDifficulty breathing, urinating, defecatingChange in behavior


Diagnostic Tests and Procedures

CBCSerum chemistry profileUrinalysisRadiographsCAT scanMRIUltrasonographyBiopsyTumor staging


Contributors to an IncreasingIncidence of Cancer

Larger population of geriatric petsAdvances in health care

An improved recognition and diagnosis of cancer

Increased willingness of both veterinarian and owner to treat cancer

Environmental changes


Feline Cancer FactsLymphoma is the most frequently

diagnosed tumor in catsSpaying female cats decreases the incidence of lymphoma by 40-50%


Canine Cancer FactsSkin cancers are the most frequently

diagnosed tumors of dogs.Mastocytomas account for 23%

Mammary tumors are the most common tumors in female dogs.Spaying a dog prior to her first heat cycle

will decrease the risk of developing mammary cancer by 7-fold.



Other Treatment Options


Gene therapyAnti-angiogenic drugsImmunotherapyAlternative therapies

AcupunctureMassageHerbal and botanical medicine

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Surgery-Indications


Mammary tumors (except inflammatory mammary cancer)

Prostate tumorsOropharyngeal tumorsSkin cancersGI tumorsLung tumorsBone tumors

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Chemotherapy-IndicationsAs sole agent

Systemic cancershematologic

malignancies metastatic

carcinomasMetastatic

sarcomas

As adjunct therapyGiven to

patients with no overt evidence of residual cancer following surgery or radiation


Chemotherapy-Limitations and Complications

Toxicities are particularly against cells of the bone marrow, GI lining, and hair follicles and can result in:ImmunosuppressionAnemiaNausea and vomittingDelayed wound healingHair loss


Onkology – question ??


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Prof. Dr. Pratiwi TS