Cancer

The second leading cause of death in the world, cancer is not one disease but a set of more than 100 related diseases in which abnormal body cells multiply and spread in uncontrolled fashion forming a tissue mass called a tumor. Not all tumors are cancerous. Benign (noncancerous) tumors tend to remain localized and usually do not pose a series threat to health. In contrast, malignant ( cancerous) tumors consist of renegade cells that do not respond to the body’s genetic controls on growth and division. To make matters worse, malignant cells often have the ability to migrate from their site of origin and attack, invade, and destroy surrounding body tissues. If this process of metastasis is not stopped, body organs and systems may be damaged, and death may result. Although some malignant cells remain as localized tumors and do not automatically spread, they do pose a threat to health and should be surgically removed.

Types of cancer

Most of the more than 250 types of cancers can be classified as one of four types:

· Carcinomas attack the epithelial cells that line the outer and inner surfaces of the body. The most common type of cancer, carcinomas account for approximately 85 percent of all adult cancers. They include cancer of the breast, prostate, colon, lungs, pancreas, and skin.

· Sarcomas are malignancies of cells in muscles, bones,, and cartilage. Much rarer than carcinoma, sarcomas account for only about 2 percent of all cancers in adults.

· Lymphomas are cancers that form in the lymphatic system. Included in this group are Hodgkin’s disease, a rare form of lymphoma that spreads from a single lymph node, and non-Hodgkin’s lymphoma, in which malignant cells are found at several sites. Approximately 60,000 new cases of lymphoma are diagnosed each year, of which 90 percent are non-Hodgkin’s lymphoma.

· Leukemias are cancers that attack the blood and blood-forming tissues, such as the bone marrow. Leukemia leads to a proliferation of white blood cells in the bloodstream and bone marrow, which impair the immune system. Although often considered a childhood disease, leukemia strikes far more adults.

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