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What are prostate cancer vaccines?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

There is a vaccine for prostate cancer, but it is used for treatment rather than prevention of the disease. Sipuleucel-T (Provenge), the currently available vaccine-there are more types undergoing clinical trials-is administered after hormone therapy has failed to produce the desired results. The idea of a cancer vaccine is that it will work with the body's immune system to attack cancerous cells, which normally go undetected.

The farther the cancer spreads from the prostate, the harder it is to successfully treat. Later stages of prostate cancer, unless detected early enough, can therefore be more difficult to treat since it has spread beyond the prostate. Once prostate cancer spreads to distant organs, a condition called metastatic prostate cancer, a cure is no longer possible.

There is a vaccine for advanced metastatic prostate cancer that extends the life of patients, says William Oh, MD, an oncologist at The Mount Sinai Medical Center. In this video, he explains why the vaccine may not proven the disease.

Dr. Marc B. Garnick, MD
Hematologist & Oncologist

Unlike vaccines that prevent infections, prostate cancer "vaccines" help fight advanced prostate cancer that no longer responds to other therapies by revving up the body's immune system. One such vaccine, sipuleucel-T (Provenge), is now commercially available. This treatment involves removing white blood cells from the patient's blood and exposing them to a protein made by prostate cancer cells called prostatic acid phosphatase (PAP). The cells are then returned to the patient. This process is repeated twice, at two-week intervals, for a total of three infusions. Cells that have been exposed to PAP prompt other immune system cells to attack prostate cancer cells. A study published in the Feb. 22, 2012 Journal of the National Cancer Institute call into question the effectiveness of sipuleucel-T.

A second prostate cancer vaccine, PROSTVAC-VF, which is still under development, works differently. Instead of using a patient's cells, it uses genetically engineered relatives of the smallpox virus, which produce slightly irregular versions of PSA and three other molecules to spur a more vigorous immune system attack on cancer cells. In a randomized, controlled phase II trial of PROSTVAC-VF, 82 men whose cancer no longer responded to hormone therapy received the vaccine; 40 men in the control group received a placebo. After three years, 30 percent of the patients in the vaccine group were alive, versus 17 percent of those in the control group. The median length of survival in the vaccine group was 25.1 months, compared with 16.6 months in the control group, an increase of 8.5 months. Reported side effects of the vaccine included fatigue, fevers, and nausea. Investigators are planning a larger phase III trial to further evaluate the vaccine's effectiveness.

Hormone or vaccine treatment can improve survival, even in patients who cannot be cured. How well you do after cancer treatment depends on whether the cancer has spread outside the prostate gland and how abnormal the cancer cells are (the Gleason score) when you are diagnosed.

Many patients can be cured if their prostate cancer has not spread. Some patients whose cancer has not spread very much outside the prostate gland can also be cured.

Dr. Mark S. Litwin, MD
Urologist

With good treatment and early diagnosis, doctors have the tools to treat prostate cancer in most cases and prevent the progression of the cancer, death, and in fact, cure the prostate cancer. However, this can only be achieved if the tumors are diagnosed early.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.