Cancer, in simple terms, occurs when cells divide in an uncontrolled manner. The human body is made up of different tissues and each tissue has its individual cellular structure. The cells in the tissues are lost through wear and tear and are constantly replaced by a process called cell division. Normally, cells divide - and produce the exact number of cells required - only when the body needs more cells. In cancer, however, cells divide for no apparent reason. In time, they form a mass of extra tissue and become big enough to be noticed as a growth or tumour.

A tumour can be benign - harmless - or malignant - bad. Benign tissues are rarely a threat to life, unless in a major organ. These do not invade the surrounding tissue and do not spread. They can usually be removed and do not come back. But malignant tumours grow into the surrounding tissue in a process called invasion. Cancer cells also break away from a malignant tumour and enter the blood stream or lymphatic system. This is how cancer spreads from the original tumour to other tissues and organs. The spread of cancer is called metastasis.

    Though the exact cause is unknown, there are various theories on what could lead to the condition. The viral theory says that a cell becomes cancerous when infected by a virus. The immunological theory says that an abnormal cell survives to become a cancer because the body's defenses somehow break down. The chemical theory rests on the evidence from animal tests that certain chemicals cause cancer by altering the genetic make-up of a cell. These are known as carcinogens; tobacco smoke is one. Relation is also known to cause cancer. Cancer has many causes, some of which are still unknown.

However, research on cancer continues. Using the molecular data from the Human Genome Project, scientists at the Cancer Research Centre at Massachusetts Institute of Technology have identified the gene-rhoC-that causes cancer cells to break away from the original tumour and form new tumours in other parts of the body. This gene triggers the sequence of events that lead to a secondary tumour.

   Women who are aged between 20 and 40 years should make it necessary to get themselves checked for cancer every three years apart from regular easy-to-do home examinations to stay alert to warning signs of cancer. For cancer, be it of the breast or the uterus, can be cured if detected early enough.

Some cancers that are common in women are oral cancer, oesophageal cancer, leukaemia, buccal mucosa, malignant lymphoma and thyroid cancer, besides breast cancer and cancer of the reproductive system.

Leukaemia: Commonly known as blood cancer and characterized by tumours in the bone marrow. In this condition, an abnormally large number of white blood cells are produced, thereby inhibiting the production of blood cells. Causes could be radiation, exposure to certain chemicals, a certain virus, drugs and hereditary factors. Symptoms include low fever and anaemia, loss of weight and appetite. Treatment involves radiation therapy, chemotherapy and surgery to remove enlarged spleen. Bone marrow transplant is also recommended.

Oral Cancer: Caused by radiation, excessive exposure to sunlight, sharp edges of broken teeth brushing against the inner lining of the mouth, chewing tobacco and high deficiency of Vitamins A and B. Symptoms include white or red patches in the mouth, sores that don't heal even after treatment, thickening or hardening or swelling in the mouth and difficulty in opening the mouth. Radiation therapy and surgery followed by radiation are the common modes of treatment.

Oesophageal Cancer: This type is quite common in India. Food habits are the main cause; consumption of very hot or very cold food, spices, chillies, animal fat, preserved meat and fish, paan, deficiency of Vitamins A and B, exposure to radiation and virus. Symptoms include difficulty in swallowing, weight loss, loss of appetite, vomiting, blood in the stool, which is dark in colour.

Lymphoma: Malignant tumours of the lymph nodes, most often in the lymph nodes of the alimentary canal, thymus and bone marrow. Also occurs in the brain, liver and kidney. Lymphomas are of two kinds. Hodgkin's disease and non-Hodgkin's disease. Symptoms are low fever and anaemia, swelling of glands most often on one side of the neck, loss of weight and appetite, and weakness. Chemotherapy and radiation is possible in both cases. Surgery to remove affected lymph glands is possible only in Hodgkin's disease.