Cancer Vaccines   A vaccine is traditionally thought of as a "killed" virus, such as the polio or measles virus, given by mouth or injection to prevent a person from ever developing a specific disease. But the term vaccine can mean many things. In cancer, scientists are developing vaccines to treat, as well as prevent, disease. For example, they are working with proteins or bits of proteins present only in tumors as a way of priming the immune system, our body's natural defense against disease. These vaccines are designed to build an army of cells and/or antibodies ready to attack and destroy cancer cells. The challenge lies in training the cells of the immune system to recognize the differences between the cancer cells and normal cells and destroy the cancer cells as it destroys harmful invaders, such as bacteria and viruses.   Advances For more than 100 years, researchers have been investigating the idea that cancer cells can be recognized and destroyed by the body's own immune system. Some significant discoveries have included: A 19th-century physician reported tumor reduction after injecting cancer patients with live bacteria, Streptococci erysipelas. Only a few early 20th-century doctors reported similar success, so researchers began to focus on other treatments, such as surgery, chemotherapy, and radiation. In the late 1950s, researchers discovered that mice could be immunized against chemically induced sarcomas (connective tissue cancers). Scientists showed that normal mice given an injection of killed cancer cells or bits of cancer cells would not develop cancer when injected later with live cancer cells. In the 1980s, scientists discovered the important role T cells (white blood cells that are an important part of the immune system) play in the immune response against cancer cells. They also discovered how the T cells recognize cells that contain bacteria or viruses or are otherwise abnormal, such as cancer cells. In animal models, these T cells could cause tumors to shrink, sometimes permanently. In recent years, scientists have discovered the tumor antigens that are recognized by these T cells, allowing them to make more defined and powerful vaccines. In the late 1970s and 1980s, a small number of patients with metastatic melanoma, treated with earlier generations of cancer vaccines made from their own tumor or from similar tumors grown in test tubes, had shrinkage of some or all of their cancer. In the early 1990s, many clinical studies using newer generations of cancer vaccines were launched. By 1996, about a dozen cancer centers, the National Cancer Institute (NCI), and about nine small biotechnology companies were testing vaccines.   Opportunities The promise of cancer vaccines lies in their potential for eradicating cancer after an initial treatment, such as surgery, has removed most of the cancer. Vaccines designed to search out and destroy any remaining cancer cells are among the most promising approaches for a cancer cure. Research opportunities are many, and include: Strengthening and Fine-Tuning Vaccines. To create more powerful and specific immune responses against cancer cells, scientists are working on ways to make vaccines more effective. This may involve combining many proteins or bits of proteins (antigens) in a single vaccine, or combining vaccines with other immune system treatments such as interleukin-2 (IL-2). Developing Vaccines for Many Different Cancers. Researchers are now conducting basic research that may lead to development of prostate, lung, colon, and other cancer vaccines. For example, cervical cancer has been linked to infection with the human papillomavirus (HPV), and a few studies testing the effectiveness of HPV vaccines for cervical cancer patients were launched this year. It may also be possible to prevent the initial infection with HPV using a vaccine, which would completely eliminate the risk of subsequently developing cervical cancer. Some other cancers are also virus and bacteria related, such as liver cancer, which can be related to the hepatitis B virus; and stomach cancer, which can be connected to the bacteria Helicobacter pylori. Scientists are now working on developing and disseminating vaccines for these cancers. Testing the Effectiveness of Vaccines in Clinical Studies. Many vaccines are being developed based on new findings from basic research. Clinical studies are needed first, to determine if the vaccines will induce the correct type of immune response in patients. Much larger clinical studies will be needed to determine if the vaccines are effective in curing cancers after initial treatments with surgery, radiation, or chemotherapy.   Additional Reading Restifo, N.P., and Sznol, M. "Cancer Vaccines," Cancer: Principles and Practice of Oncology, 5th ed., edited by Vincent T. DeVita, Jr., Samuel Hellman, Steven A. Rosenberg, Philadelphia: Lippincott-Raven Publishers, 1997. Old, L.J. "Immunotherapy for Cancer," Scientific American, Special Issue: What You Need to Know About Cancer, September 1996.   Statistics are from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database (January 1997) and from the American Cancer Society's Cancer Facts and Figures­1997, which contains estimates based on SEER data. The Cancer Information Service provides a nationwide telephone service for cancer patients, and their families, the public, and health care professionals. The toll-free number is 1-800-4-CANCER (1-800-422-6237); services are provided in English and Spanish. People with TTY equipment may call 1-800-332-8615. Back to How to Get It Return to Cancer Research Main Page