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Combo Therapy Stalls Return of Prostate Cancer

Vaccine, hormone treatment seems to delay recurrence, study finds

MONDAY, Aug. 8, 2005 (HealthDay News) -- An unusual combination is showing promise as a potential treatment for prostate cancer patients whose disease threatens to return.

Federal scientists found that reducing hormone levels and administering a cancer vaccine appears to postpone recurrence of prostate cancer in some patients. While the research still has to go through another stage of testing before the treatment could reach government approval, a study co-author is encouraged.

"If you come in from two fronts, you may be more successful at beating the enemy than with one approach," said Dr. Philip Arlen, director of a research group at the National Cancer Institute.

The research appears in the August issue of the Journal of Urology.

Despite advances in treatment, prostate cancer remains the most commonly diagnosed cancer in the United States and a major killer, taking the lives of more than 30,000 American men each year.

In some cases, it returns after treatment with drugs that lower the levels of male sex hormones. Essentially, the body becomes immune to the hormone treatment and tests show that cancer may be developing, even though tumors can't yet be seen.

In the new study, researchers tried to boost the effects of a cancer vaccine by combining it with hormone-dampening treatment in those at high risk of developing tumors again. According to the researchers, this approach has never been tried before.

In a trial involving 21 patients who received vaccines, those who also underwent specific hormone-reduction treatment after six months of treatment went an average of 25.9 months until the cancer recurred. By contrast, those who got the vaccine but not the hormone treatment went a year before recurrence.

The patients didn't report side effects from the vaccine, but some developed lung problems from the hormone treatment.

With the help of the vaccine, the researchers apparently primed the immune systems of the patients to let the hormone treatment do its preventive work, Arlen said. Unlike common vaccines that stop disease before it infects a person, the prostate cancer vaccine is designed to stop recurrence of illness.

Arlen acknowledged that even the combination treatment didn't keep recurrence of cancer at bay for very long. "The tumor finds escape mechanisms," he said. "They start outsmarting the hormone (treatment)." However, researchers want to explore what will happen if they give the combination treatment earlier.

For now, the treatment is still in the testing stage. "It's a promising treatment for cancer patients who have begun to resist treatment," Arlen said, "but it needs to be confirmed with larger studies."

More information

To learn more about prostate cancer, try the Prostate Cancer Foundation.

SOURCES: Philip Arlen, M.D., director, Clinical Research Group, Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Md.; August 2005 Journal of Urology
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