· Cancer is an abnormal and uncontrolled multiplication of cells resulting in the formation of tumor.
· Normal cells show a contact inhibition (contact with the other cells inhibits their uncontrolled growth). Cancer cells appear to have lost this property.
· Tumors are 2 types:
o Benign: Confined to the place of its origin. Harmless.
o Malignant: Spread and invade nearby tissues. Harmful.
· Metastasis: The spread of cancer cells from one part of the body to another.
Types of cancer
o Carcinoma : cancer of epithelial cells
o Sarcoma : cancer of connective tissues.
o Melanomas : cancer of melanocytes
o Leukemia : blood cancer
o Lymphomas : cancer of spleen and lymph nodes.
Causes of cancer (Carcinogens)
§ Chemical agents: Tobacco smoke (major cause of lung cancer), vinyl chloride, caffeine, nicotine, mustard gas etc.
§ Biological agents: E.g. oncogenic viruses, cellular oncogenes (c-onc or proto oncogenes) etc. When C-onc (in normal cells) is activated the cells becomes oncogenic.
Cancer detection and diagnosis
o Biopsy: A thin piece of the suspected tissue is stained and examined under microscope (histopathological studies).
In case of leukemia: Biopsy & histopathological studies. Blood & bone marrow tests for increased cell counts.
o Radiography (use of X-rays), CT (Computerized tomo-graphy) scan & MRI (Magnetic Resonance Imaging).
o Use of Antibodies against cancer-specific antigens.
o Techniques of molecular biology to detect genes related to cancer. Such individuals may be advised to avoid exposure to particular carcinogens (e.g. tobacco smoke).
Treatment of cancer
o Chemotherapy: Use of chemotherapeutic drugs. Many drugs have side effects like hair loss, anaemia etc.
o Immunotherapy: The patients are given biological response modifiers (e.g. α- interferon) which activates their immune system and helps in destroying the tumor.
o Most cancers are treated by combination of surgery, radiotherapy and chemotherapy.