It is one of the most dreaded diseases of human beings and is a major cause of death all over the world. More than a million Indians suffer from cancer and a large number of them die annually.
In our body, cell growth and differentiation is a highly controlled and regulated process. But in cancer cells, there is an abnormal and uncontrolled division of cells due to breakdown of these regulatory mechanisms.
Normal cells show a property called contact inhibition, in which, the dividing cells when in contact with other cells, inhibit their uncontrolled growth but cancer cells do not have this property. Therefore, cancerous cells continue to divide giving rise to mass of cells called neoplasm or tumors.
Types of Tumors:-
(i) Benign Tumors:- It remains confined to their original location and do not spread to other parts of the body and hence cause little damage.
(ii) Malignant Tumors:– it is a tumor where neoplastic or tumor cells divide and grow very rapidly, invading and damaging surrounding normal tissues, starving the normal cells by competing for vital nutrients. Cells sloughed from such tumors reach distant site through blood and whenever they get lodged In the body, they start a new tumor formation. This property is metastasis and is the most feared property of malignant tumors
Causes of cancer/Carcinogenic:-
Transformation of normal cells into cancerous, neoplastic cells may be induced by physical, chemical and biological agents.
(i) Physical agents:- Ionising radiations like X-rays and gamma rays and non-ionizing radiation like UV rays cause DNA damage which leads to neoplastic transformation.
(ii) Chemical agents:- Chemical carcinogens are present in tobacco smoke which have been identified as a major cause of lung cancer. For instance, asbestos exposure can lead to cancer of lungs while carcinogen like cadmium oxide is associated with prostate cancer.
Types of cancer:-
(a) Carcinomas are malignant growths of the epithelial (ectodermal) tissues that cover or line the body organs. e.g., skin cancer, breast cancer, lung cancer, cancer of the stomach and pancreas (about 85 percent of all tumors are carcinomas).
(b) Sarcomas are malignant growths arising in tissues derived from primitive mesoderm. e.g., bone tumors, cancer of lymph nodes.
(c) Leukaemias result from unchecked proliferation of cell types present in blood and their precursors in the bone marrow.
Other types of cancers are:-
Melanoma : Cancer of pigment cells of the skin
Adenocarcinoma : Cancer of glands
Lymphoma : Cancer of lymphatic tissue
Glioma : Cancer of glial cells of CNS
Detection and Diagnosis:-
An early detection of cancer is like saving, but if it spreads to various parts and organs, the treatment becomes ineffective. The diagnosis of cancer is usually done by
(a) Biopsy and histopathological studies of the suspected tissue. In this a piece of suspected tissue is cut into thin sections, stained and examined under a microscope by a pathologist for detection of cancerous cells.
- b) Blood and bone marrow tests for increased cell counts in the case of leukaemia.
(c) Techniques like radiography (use of X-rays).
CT (Computed tomography) and MRI (Magnetic Resonance Imaging) are useful to detect cancers of the internal organs. CT scan uses X-rays to generate a three dimensional image of internal organs while MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.
(d) Antibody against cancer specific antigens are also used for detection of certain cancers. e.g; Herceptin.
(e) Techniques of molecular biology can be used to detect genes individuals with inherited susceptibility for certain cancers. After detection or identification of these genes in any individual, they may be advised to avoid exposure to particular carcinogens to which they are susceptible (e.g. Tobacco smoke in case of lung cancer).
Treatment of Cancer:-
Common treatment prescribed for different types of cancers are:-
(i) Surgery:- Generally a tumor is surgically removed wherever possible.
(ii) Radiotherapy/Radiation Therapy:– Tumor cells are irradiated lethally by gamma radiations taking proper care of the normal tissues surrounding the tumor mass or neoplasm. e.g., use of l131 for thyroid cancer.
(iii) Chemotherapy:- Several chemotherapeutic drugs are used to kill cancerous cell. Some of these are specific for particular tumar e.g., two anticancer drugs, vincristine and vinblastine, used in the treatment of leukaemia are obtained from common weed Catharanthus roseus. Majority of drugs have side effects like hair loss, anemia eyc.
(iv) Immunotherapy:- Sometimes tumor cells are seen to avoid detection and destruction by immune system. So the patients are given substances called biological response modifiers such a α-interferons which activate their immune system and help in destroying the tumor
Cancer is a disease characterized by the uncontrolled growth and spread of abnormal cells in the body. If the growth is not controlled, it can result in death.
Cancer can be caused by a variety of factors, including genetic mutations, environmental exposures (like tobacco smoke, radiation, and certain chemicals), and lifestyle factors (such as diet, physical activity, and infections).
Cancer is typically diagnosed through a combination of methods, including medical history, physical examination, laboratory tests (like blood tests), imaging tests (such as X-rays, CT scans, MRI), and biopsies (where a sample of tissue is examined under a microscope).
Common types of cancer include breast cancer, prostate cancer, lung cancer, colorectal cancer, and skin cancer (melanoma and non-melanoma).
Symptoms vary depending on the type of cancer but can include lumps, unexplained weight loss, fatigue, changes in skin, persistent cough, changes in bowel or bladder habits, and difficulty swallowing.
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