Related Pages What Is a Clinical Trial? 1 A basic description of the reason for, and the kinds of, clinical trials. Cancer Vaccines 2 A fact sheet about cancer vaccines, which are intended either to treat existing cancers (therapeutic vaccines) or to prevent the development of cancer (prophylactic vaccines).

For many years, the treatment of cancer was focused primarily on surgery, chemotherapy, and radiation. However, as researchers learn more about how the body fights cancer on its own, therapies are being developed that harness the potential of the body's defense system in this fight, including efforts to prevent some forms of cancer.

The body's defense system - called the immune system - consists of a network of specialized cells and tissues that fight infection and disease. Therapies that use the immune system to fight or prevent cancer are called biological therapies.

Cancer vaccines represent an emerging type of biological therapy that is still mostly experimental. Many clinical trials are underway to test vaccines as potential treatments for a wide variety of cancer types. The U.S. Food and Drug Administration (FDA) has not approved any cancer vaccine as a standard treatment for any type of cancer. This means that cancer-fighting vaccines are only available to those who enroll in clinical trials.

The FDA has, however, approved two vaccines that can help prevent cancer. One of these vaccines prevents infection with the human papillomavirus (HPV), which causes almost all cervical cancers (for more information, see Human Papillomavirus (HPV) Vaccines for Cervical Cancer ³). The other vaccine prevents infection with the hepatitis B virus, which can cause liver cancer. Other vaccines that may prevent or reduce the risk of cancer are also being tested in ongoing clinical trials.

Glossary Terms

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical study.