Chemotherapy, or cytotoxic therapies

Chemotherapy is the use of drugs to target rapidly growing cells in an effort to destroy cancer cells. Chemotherapy drugs kill healthy cells as well as cancer cells. The drug is referred to as systemic, since it travels through the entire body. Chemotherapy medications may be given through the vein (intravenously) or by mouth (orally). Because chemotherapy drugs affect all rapidly-dividing cells in the body (not just cancer cells), these drugs may have severe side effects. Common side effects of chemotherapy include fatigue, nausea, hair loss, and trouble concentrating. Peripheral neuropathy, or nerve damage, may occur as well.

The two main types of targeted therapy are small-molecule drugs and monoclonal antibodies.

• Small-molecule drugs can enter cancer cells and target certain proteins and enzymes that are involved in key cell functions such as growth and division. Small-molecule drugs can block these substances, and prevent them from stimulating tumor growth.
• Monoclonal antibodies function very much like the antibodies that the body produces naturally in response to infection and disease. Monoclonal antibodies bind to harmful substances in the body, such as cancer cells, viruses, and bacteria, and signal the body's immune system to find and destroy the harmful substances. These antibodies target specific proteins on cancer cells that are involved in cancer growth and spread.

Immunotherapies

Immunotherapy is a new cancer treatment that stimulates the body's immune system to attack cancer cells. Monoclonal antibodies are considered a type of immunotherapy, as well as a type of targeted therapy, because these medications cause the immune system to target and destroy cancer cells. Another type of immunotherapy is immune checkpoint inhibitors. The immune system has "checkpoints," which are proteins that bind to cells and tell the immune system to attack the cells or leave them alone. Sometimes cancer cells can have large amounts of these checkpoint proteins, causing the immune system to ignore them. Immune checkpoint inhibitors block these checkpoints and signal the immune system to attack the cancer cells. Two other common types of immunotherapy are interferons and interleukins. Interferons stimulate the immune system to fight cancer or infections. Interleukins help immune cells to grow and reproduce quickly. Cancer vaccines are uncommon, but are currently being studied in clinical trials.

Combination therapy

Each of these types of drugs may be combined with one another, or with other cancer treatments such as chemotherapy and/or radiation therapy. In some cases, cancer cells can become resistant to chemotherapy or targeted therapy, and combinations of treatments may be recommended.