Cancer
Cancer causes about 4
million deaths annually throughout the world. In India more than one million
people suffer from cancer. Cancer is derived from Latin word meaning crab. The
study of cancer is called Oncology (Oncos- Tumor).
Cancer is an abnormal
and uncontrolled division of cells that invade and destroy surrounding tissue
forming a tumor or neoplasm (new growth). It is a heterogenous group of
cells that do not respond to the normal cell division.
The cancerous cells
migrate to distant parts of the body and affect new tissues. This process is
called metastasis. The frequent sites of metastasis are lungs, bones,
liver, skin and brain.
Cancers are classified
on the basis of the tissues from which they are formed.
1. Carcinomas arise from epithelial
and glandular tissues. They include cancers of skin, lung,
stomach and brain. About 85% of the tumours are carcinomas
2. Sarcomas are occur in the
connective and muscular tissue. They include the cancer of
bones, cartilage, tendons, adipose tissue and muscles. These form 1% of all
tumours.
3. Leukaemia are characterized by an
increase in the formation of white blood cells in the bone marrow and lymph
nodes. Leukaemia are called blood cancers. Most common type of cancer
which also affect children below 15 years of age.
Cancer causing agents
are called carcinogens. They are physical, chemical agents,
ionizing radiations and biological agents.
Physical Irritant: Heavy smoking causes
lung cancer and cancers of oral cavity, pharynx (throat) and larynx.
Betel and tobacco chewing causes oral cancer. Excessive exposure to sunlight
may cause skin cancer.
Chemical agents: Nicotine, caffeine,
products of combustion of coal and oil, pesticides, asbestos, nickel,
certain dyes and artificial sweetners induce cancer.
Radiations: Ionizing radiations like
X-rays, gamma- rays, radioactive substances and non-ionising radiations
like UV rays cause DNA damage leading to cancer.
Biological agents: Cancer causing viruses
are called oncogenic viruses.
The treatment of cancer
involves the following methods:
Surgery: Tumours are removed by
surgery to prevent further spread of cancer cells.
Radiation therapy : Tumour cells are
irradiated by lethal doses of radiation while protecting the surrounding
normal cells.
Chemotherapy: It involves
administration of anticancerous drugs which prevent cell division and
are used to kill cancer cells.
Immunotherapy: Biological response modifiers
like interferons are used to activate the immune system and help in destroying
the tumors.
Cancer control
programmes should focus on primary prevention and early detection.
To prevent lung cancer
tobacco smoking is to be avoided and protective measures to be taken against
exposure to toxic pollutants of industries. Excessive exposure to radiation is
to be avoided to prevent skin cancer.
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