Principles of Neoplasia And Growth Disorders

Dr: Wael H Mansy, MDAssistant Professor

Clinical Pharmacy Department-College of Pharmacy

King Saud University

• List the main characteristics of benign and malignant tumors. • Describe the nomenclature used for various types of tumors. • Discuss tumor metastasis. How do tumors facilitate their own spread? What are some common sites of metastasis for tumors? • Define oncogenesis. Discuss some of the theories of how it might occur. List some viruses that are oncogenic, as well as the cancers they may cause.

Study objectives

• What is a carcinogen? List some substances that are carcinogenic. • List the local and systemic effects of cancer. • Define cancer cachexia. Why might it occur? • Describe the system by which tumors are “staged.” • What are tumor cell markers? How are they used clinically? • Discuss the various treatment options for cancer. Include the draw-backs of each.

Cancer Definition

Cancer is a class of diseases in which a group of cells display uncontrolled growth(1) (division beyond the normal limits), invasion(2) (intrusion on and destruction of adjacent tissues), and sometimes metastasis(3) (spread to other locations in the body via lymph or blood)

These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize.

*Healthy cells are programmed to “know *Healthy cells are programmed to “know what to do and when to do it”.what to do and when to do it”.

*Cancerous cells do not have this programming *Cancerous cells do not have this programming and therefore grow and replicate out of control. and therefore grow and replicate out of control. They also serve no physiological function. They also serve no physiological function. These cells are now termed a neoplasm.These cells are now termed a neoplasm.

*Most cancers form a tumor but some, like leukemia, do not.

*The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is Oncology.

*Although cancer can arise at any age, the incidence of cancer increases proportionally with increasing age.

*The most common sites for cancer development are the prostate, breast, lung and colon.

Tumor or neoplasm A mass of tissue in which the growth rate is excessive and uncoordinated when compared with normal tissues.

Cancer terminology

Benign neoplasm -Tumor cells that tend to be clustered in a single mass and are not malignant. -Benign tumors usually will not cause death unless they interfere with vital function. -Specific names end with “oma” for example, a hepatoma is a benign tumor of the liver, whereas a hepatocarcinoma is a malignant tumor.

• *Add “oma” to the tissue type• -Gland—adenoma; a glandular tumor of the thyroid is

a thyroid adenoma; pituitary adenoma ..etc• -Bone—osteoma• -Fatty tumor—lipoma• -Cartilage—chondroma• -Smooth muscle—leiomyoma (a smooth muscle

benign tumor of the uterus is called a leiomyoma or FIBROID)

Malignant neoplasm— Tumors that have the ability to metastasize or break loose and spread to other areas of the body. If untreated, such tumors can cause great suffering and death. Specific examples:Carcinoma— Malignant tumor of epithelial cell origin.Sarcoma — Malignant tumor of skeletal or connective tissue originLymphoma— Malignant tumor of lymphatic tissue.Glioma— Malignant tumor of the glial support cells in the central nervous system.

Benign Malignant

Slow growth rate Rapid growth rate

Encapsulated Non-encapsulated

Well-differentiated cells Non-differentiated cells (anaplasia)

Resemble tissue of origin Loss of contact inhibition

Do not metastasize Metastasize readily

They can be removed and they don’t come back (usually)

They can be removed and they come back (usually)

Contact inhibition is the natural process of arresting cell growth when two or more cells come into contact with each other.

Characteristics of Neoplasia

The ability of tumor cells to spread to other parts of the body and establish secondary tumors.

Metastasis

Malignant tumor cells can break off and utilize blood vessels or lymphatic vessels to spread to other areas of the body.

Tumor cells enhance their potential for metastatic spread by:

1-Releasing Protease enzymes that digest the extracellular matrix surrounding adjacent cells. Malignant tumor cells

2-Production of growth factors that stimulate the formation of new blood vessels (angiogenesis), which in turn support the rapid growth of tumor cells e.g. Epidermal Growth Factor (EGF).

Certain organs such as the lungs are prime locations for the formation of metastases because of the large amount of blood flow they receive from the body.

The liver is also a common site of metastasis for tumors originating in the gastrointestinal tract because blood draining the intestines must first pass through the liver via the hepatic portal system.

Breast cancer — Bones, lymph nodes (axillary), brainLung cancer — Many organs including liver, brain and boneProstate cancer — Bones, lungs, liver, endocrine glandsColon cancer — LiverTesticular cancer — Lungs, liverOvarian cancer — Peritoneum, liver, lungs, diaphragm

Common Sites of Metastasis for Selected Cancers

Theories of oncogenesis

It is the process by which normal cells are transformed into cancer cells; 3 theories:

1-Abnormalities of tumor suppressor/inducer genes.

2-Mutation of DNA

3-Hereditary

Anti- oncogenes (Tumor Suppressor Genes):

1-Abnormalities of tumor suppressor/inducer genes

The genes that code for several proteins produced within cells are known to limit cellular division and suppress cell growth e.g. p53 protein

Failure of these anti-oncogenes may lead to the unregulated cellular division that is characteristic of cancer cells.

proto-oncogenes

*Genes that produce proteins and substances that enhance cellular growth and proliferation. Excessive activity of these genes (or a lack of their regulation) may likewise cause excessive cellular division and growth e.g. RAS, WNT & ERK.

*HER-2/neu (Human Epidermal growth factor Receptor 2) is a receptor involved with cell growth; when its gene is amplified, cells grow much faster. It present in 20-30% of breast cancers

Damage of cellular DNA, either directly or through the production of toxic intermediates such as free radicals.

Numerous chemical, physical and biologic agents have been shown to be carcinogenic

Mutations of cellular DNA can lead to the formation of cells with abnormal growth and differentiation patterns

Certain viruses are also oncogenic in that they may induce mutations in host cell DNA or alter rates of cellular transcription

Mutation of DNA

1-Chemicals — Many such as benzene, cigarette smoke, aromatic hydrocarbons2-Radiation — radon gas, radioactive materials, ultraviolet radiation3-Occupational exposure — Asbestos, coal dust, uranium, solvents4-Dietary factors — High-fat diet, excessive alcohol intake, nitrosamine preservatives, grilled or charred foods5-Hormones — Estrogens, progesterone

Possible Cancer-Causing Agents

1-Human Papillomavirus — Cervical carcinoma2-Hepatitis B Virus — Liver cancer3-Epstein–Barr Virus — Burkitt’s lymphoma, nasopharyngeal cancer4-HIV Virus — Kaposi’s sarcoma

Oncogenic Viruses in Humans

*A genetic predisposition has been observed for a number of cancers including colon cancer, breast cancer, retinoblastoma and certain forms of leukemia and lymphoma*Philadelphia chromosome is present in 95% of Chronic Myelogenous Leukemia (Abnormal Chromosome 22- loss of part of long arm)

.

Hereditary

Many cancers may be asymptomatic in the early stages. As the tumors continue to grow, they affect local tissues as well as the overall body.

Manifestations of cancer

1. Local effects of cancer

• Compression of blood vessels Ischemia• Pain• Bleeding• Infection• Altered tissue function

2. Systemic effects of cancer

• Fatigue• Cachexia • Bleeding and hemorrhage•Anemia due to chronic bleeding or bone marrow destruction; this anemia may be exacerbated by chemotherapy• Altered organ function•Abnormal hormone production from an affected gland or directly from certain types of hormone-producing tumors.

A complex syndrome characterized by anorexia, weight loss and lean body (muscle) wasting seen in a significant percent of patients with cancer and AIDS.

Cachexia

A number of metabolic abnormalities have been demonstrated in patients with cachexia that lead to poor utilization of nutrients and overall malnutrition.

A key factor in cachexia appears to be the production of cytokines such as tumor necrosis factor and interleukins in response to the presence of cancer.

Tumors are classified or “staged” based upon the “TNM” system that includes a description of tumor size (T), involvement of lymph nodes (N) and metastasis (M).

Tumor staging

Tumor Staging

• T — Primary tumor (Is there a tumor and if so how big is it?)

• TX — Primary tumor cannot be assessed

• TO — No evidence of primary tumor

• Tis — Carcinoma in situ

• T1–T4 — Increasing size of tumor

Tumor Staging

• N — Involvement of lymph nodes (Has the tumor spread to the lymph nodes?)

• NX — Regional lymph nodes cannot be assessed• NO — No evidence that the tumor has

metastasized to lymph nodes in the region of the primary tumor

• N1–N3 — Progressive involvement of regional lymph nodes

Tumor Staging

• M — Distant metastasis (Has the tumor spread to distant sites in the body?)

• Mx — Distant metastasis cannot be assessed

• MO — No evidence of distant metastasis

• M1–M4 — Single or multiple sites of metastasis have been located

Tumor cell markers

• Substances produced by or found on the surface of tumor cells.

• Tumor cell markers may be used clinically to screen for the presence of tumor cells in the body OR for prognosis.

Tumor cell markers

• α-Fetoprotein

• Secreted by embryonic liver cells.

• High levels seen in liver, ovarian and testicular cancer

• May also be observed with viral hepatitis

Tumor cell markers

• Prostate-specific antigen (PSA)

• Markedly increased in prostatic cancer

• Slightly elevated in benign prostatic hypertrophy

Tumor cell markers

• CA 15-3

• Elevated in breast cancer

• High levels often indicate advanced or metastatic breast cancer

• May be elevated in benign breast disease or liver disease

Tumor cell markers

• CA 19-9

• Elevated in cancers of the gastrointestinal tract and pancreas

• May also be elevated in gallbladder disease and pancreatitis

Tumor cell markers

• CA 27-29

• Elevated in breast cancer.

• May also be elevated in benign breast disease as well as disease of the kidney and liver

Tumor cell markers

• CA 125• Elevated in ovarian cancer• May be elevated in pregnancy and with

pelvic inflammatory disease• Human chorionic gonadotrophin • Used as a marker for a number of different

cancers e.g.choriocarcinoma.• Elevated in pregnancy.

Tumor cell markers

• Drawbacks to the use of tumor markers in cancer diagnosis include that they may not be specific for a certain type of cancer

• By the time tumor cell markers are detected, the particular cancer may be well progressed (late stage).

• Certain non-cancerous conditions may also be associated with the appearance of some of these markers in the blood

Visualization

• Radiography, computer tomography (CT scans), magnetic resonance imaging (MRI)

• Endoscopy may also be utilized to visually detect tumors in the bronchi and gastrointestinal tract

• Identifies the presence of a tumor can also be used to evaluate metastasis.

Biopsy

• Removal of a piece of suspect tissue for detailed histologic or histochemical analysis

• May be accomplished surgically, by a needle biopsy, by scraping cells from a surface (Pap smear) or by endoscopic biopsy.

Rationale for therapy

• Cancer treatment may include surgical removal of tumors, as well as chemotherapy and/or radiation therapy to kill or arrest rapidly growing tumor cells.

• A number of immune-based treatments are currently under investigation as alternatives to toxic chemotherapy and radiation therapy.

• Treatment with specific hormones has also been shown to inhibit the growth of certain types of cancers

Surgical removal

If accessible, tumors should be surgically removed. Often accompanied by chemotherapy or radiation therapy to kill any cancer cells that are not removed or have metastasized.

Chemotherapy Drugs• Alkylating agents and nitrosureas (examples: cyclophosphamide, carmustine)Cytotoxic to cancer cells due to alkylation of cancer cell DNAMajor toxicities include nausea and vomiting, and bone marrow suppression

• Antimetabolites (examples: methotrexate, fluorouracil)Inhibit synthesis of essential nucleotides and nucleic acids in cancer cellsMajor toxicities include myelosuppression, nausea, vomiting, oral and

gastrointestinal ulceration• Plant alkaloids (examples: vinblastine, vincristine)Disrupt mitosis in cancer cells by interfering with formation of the mitotic spindleNumerous toxicities including cardiotoxicity, bone marrow depression, neurologic

and alopecia

• Antibiotics (examples: doxorubicin, bleomycin).Bind directly to cancer cell DNA to block the formation of new RNA or DNAMajor toxicities include bone marrow suppression, alopecia

Radiation therapy

• Radiation therapy utilizes ionizing or particle beam radiation to destroy cancer cells that are highly mitotic and most susceptible to the lethal effects of radiation.

• Radiation therapy can have a number of localized and systemic side effects including alopecia, diarrhea, tissue irritation and organ inflammation.

THANK YOU