The over 150 different types of cancer are classified into four major groups:

1. Carcinomas—Nine in ten cancers are carcinomas, which involve the skin and skin-like membranes of the internal organs.
2. Sarcomas—Involve the bones, muscles, cartilage, fat, and linings of the lungs, abdomen, heart, central nervous system, and blood vessels.
3. Leukemias—Develop in blood, bone marrow, and the spleen.
4. Lymphomas—Involve the lymphatic system.