Chemotherapy is used to treat cancer, a condition in which abnormal cells grow and divide, forming tumors that in some cases can spread throughout the body. Most cancers are named for the places they originate—e.g., the lung or the breast. There are five main categories of cancer:
- Carcinoma: Cancer that begins in the skin or tissues lining or covering internal organs.
- Sarcoma: Cancer that begins in bone, cartilage, fat, muscle, blood vessels, and other connective or supportive tissue.
- Leukemia: Cancer that begins in blood-forming tissue such as bone marrow.
- Lymphoma and myeloma: Cancers that form in the cells of the immune system.
- Central nervous system cancers: Cancers that begin in the tissues of the brain and spinal cord.