What is Cancer?
Cancer is a name given to a group of diseases which occur when normal cells begin to change and grow without control.
The human body is made up of about 200 different types of cells which total in trillions.
Generally, in the body, there is a constant turnover of these cells with old ones dying and new ones being formed to replace them. This turnover is usually under a very tight control. Cancer develops when this control is lost. These cells growing out of control make up a lump or a tumour when they reach a certain size. Once a cancer develops, it can invade structures around it and can spread to other parts of the body through the blood stream or lymph channels.
Cancer can develop in any part of the body. Generally, the name of the cancer implies the site of origin. For example, breast cancer is cancer that has started in the breast, lung cancer is cancer that has started in the lung.
There are lots of other terms used to describe cancer. Tumour is a word that is commonly used.
Tumour doesn’t always mean cancer. A tumour can be a benign tumour (one that does not invade or spread to other parts) or a malignant one. A benign tumour is not a cancer.
A cancer is a malignant tumour that can invade and spread. Once it has spread, it is called as a metastatic cancer or secondary cancer. Terms such as “lump” or “growth” are also commonly used. These terms can be either benign or malignant.
Apart from individual names like breast cancer or lung cancer, cancers can be assigned to groups based on the type of cells they start from.
Cancers that begin in cells that line the inner and outer surfaces of the body are called Carcinomas. This can be further divided based on the type of cells like squamous cell carcinoma or adenocarcinoma (developing from glands).
Cancers that begin in cells of the connective tissue, for example from muscle, bone, cartilage and fat are called Sarcomas.
Cancers that originate from the blood forming cells such as bone marrow are called Leukaemias. Cancers that originate from the lymphatic system are called Lymphomas.
Cancer in India
Cancer in India is increasing. According to Global burden of diseases, injuries and risk factors study (GBD) published in 2018 which looked at cancer in India between 1990 and 2016, the number of new cancers and deaths doubled in numbers between those periods. This was mainly due to population growth and an ageing population. Now about 8.3% of all deaths in India are due to cancer.
Tobacco was the leading risk factor for cancer during that period even though the use of tobacco reduced in that time. It accounted for 10.9% of cancers. Alcohol was blamed for 6.6% and diet for 6% of all cancers. The amount of tobacco used reduced during the period, but the alcohol intake increased. Cancers associated with alcohol intake showed an upward trend.
The number of cancers increased from 548,000 in 1990 to 1,069,000 in 2016. States with the highest rates of cancer were Mizoram, Kerala, Haryana, Delhi, Assam, Meghalaya, Karnataka, Goa and Himachal Pradesh.
Breast cancer was the leading cancer in women in India and showed a nearly 40% increase in the number between 1990 and 2016. Other common cancers in women included cervix, stomach, colon and rectum and lip and oral cavity cancers.
In men the common cancers included lung, lip and oral cavity, pharynx, stomach and leukaemia.