Friday, November 14, 2014

Cancer: Types, causes, diagnosis and Treatment

CANCER

·   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.
·   Cancer cells form masses of cells called tumors.

·   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)


§ Physical agents: E.g. Ionizing radiations like X-rays and gamma rays and non-ionizing radiations like UV.
§ 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 Radiation therapy: Tumor cells are irradiated lethally, without damaging surrounding normal tissues.
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 Surgery.
o Most cancers are treated by combination of surgery, radiotherapy and chemotherapy.


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