Overview of Cancer Types
A cancer is an irregular cell development (generally originating from an irregular single cell). The cells have lost normal mechanisms of control and are therefore able to continuously replicate, invade neighboring tissues, migrate to distant areas of the body and facilitate the development of new blood vessels from which the cells receive nutrients. Cancerous (malignant) cells may develop out of any body tissue.
As cancer cells expand and multiply they form a mass of cancerous tissue — called a tumour — invading and killing normal adjacent tissues. The word tumour refers to a mass or an irregular development. Tumours may be cancerous or noncancerous. Cancerous cells from the primary (initial) site can spread (metastasise) throughout the body.
Cancers are categorized in two ways:
- by the type of tissue where the cancer originates (histological type)
- by the primary site or location in the body where the cancer first grew
Histological classification of cancer includes:
Leukaemia and lymphoma are tumours of the blood and blood producing tissues and cells. Leukaemia starts from blood forming tissue such as bone marrow, and causes abnormal blood cells to be produced. Lymphoma cancer cells enlarged lymph nodes, creating large masses in the armpit, groin, abdomen or chest.
Carcinomas are cell cancers lining the skin, the lungs, the digestive tract and the internal organs. Examples of carcinomas include skin cancer, lung cancer, colon cancer, stomach cancer, breast cancer, prostate cancer, and thyroid cancer. Carcinomas usually occur more frequently in older people than they do in younger ones.
Sarcomas are tumours of mesodermal cells. Mesodermal cells usually shape muscles, blood vessels, bone, and connective tissue. Leiomyosarcoma (smooth muscle cancer located in the wall of digestive organs) and osteosarcoma (bone cancer) are examples of sarcomas. Usually, sarcomas occur more frequently in younger people than in older people.
Most common cancers in men and women in India, according to primary site are:
Most cancers are now curable, particularly if diagnosed early, and there is also the possibility of long-term remission in those diagnosed later. It is also uncertain that all cancers, especially breast cancers identified at a very early stage by mammography or prostate cancers identified by prostate-specific antigen (PSA) testing, can grow and become life threatening. Effective cancer diagnosis is likely to improve the chance for recovery.
As in many advanced cancer cases, when cure is not feasible, judicious treatment with radiation therapy, medications, and/or surgery can enhance quality of life and extend survival. However, such treatment may be poorly tolerated in other patients, especially the elderly and those with comorbid conditions, and palliative care may be the better option.