Cancer Treatment

Biological response modifiers increase a person's ability to fight cancer by strengthening natural body processes. Some biological modifiers are immunotherapies-that is, they stimulate the body's immune system to attack cancer cells. Other biological modifiers improve the body's ability to withstand aggressive drug therapy. The body makes small quantities of many biological response modifiers. Scientists can now produce some of them in laboratories in large quantities using techniques of molecular biology.

Monoclonal antibodies are an important type of immunotherapy. They are designed to recognize certain proteins that are found on the surface of some cancer cells. The monoclonal antibody then binds onto the protein. This action then triggers the body's immune system to attack the cancer cells and can also cause the cells to destroy themselves. For example, about one-third of breast cancer patients have high levels of a protein called HER2 on the surface of the cancer cells. Scientists have developed a monoclonal antibody that binds onto this protein and stops the cancer cell from growing and dividing. The antibody also causes the body's immune system to attack the cancer cells.

Some experiments are investigating the ability of monoclonal antibodies to deliver microscopic doses of drugs or radiation directly to tumor cells. Scientists are working to make use of tumor-surface antigens to produce vaccines against certain kinds of cancer. Antigens are viruses or other foreign substances in the body that trigger the immune response.

Erythropoietin, another biological response modifier, increases a cancer patient's production of red blood cells. Many kinds of chemotherapy cause anemia by killing red blood cells. In an anemic person, the blood cannot provide the tissues with enough oxygen, causing the patient to feel weak or tired. Erythropoietin helps cancer patients withstand the stress of chemotherapy and maintain an active life.