What is Cancer?

The term cancer denotes a disease in which abnormal cells divide freely due to loss of control and invade healthy tissues. Cancer cells have the ability to spread to other parts of the body. These cells spread to other parts of the body through the blood and lymph systems. The term cancer does not denote one disease but many diseases. There are about 100 different types of cancer.  Most cancers are named after the organ or the cell type from which they originate such as cancer of oesophagus is called oesophageal cancer and cancer of the basal cells of the skin is called basal cell carcinoma.

The human body is made up of different types of cells. The cells of the body grow and divide in a controlled way to produce new cells needed to replace the old and dead cells to keep the body healthy. In some people this orderly way of new cell production to replace old and damaged cells goes wrong. This, results in the formation of more than needed cells and the extra cells may result in formation of a mass of tissue called a tumour. But all cancers or tumours are not cancerous. Some tumours are benign and some are malignant.

• Benign tumours: This mass of tissue is not cancerous and in most cases it can be removed and does not come back. In addition these cells do not spread to other parts of the body.
• Malignant tumours: These are cancerous in the sense that they invade nearby tissues and can spread far and wide to other parts of the body.
• Some cancers do not result in the formation of a tumour (mass of tissue). For example, in the case of leukaemia (cancer of the bone marrow and blood), the cancer can grow rapidly and invade other tissues but no mass is formed.

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