Although the evidence of prolonged longevity is slight, the U.S. Food and Drug Administration on Thursday ruled a new immune system treatment for advanced prostate cancer is safe and effective enough to be sold. (File Photo)

    BEIJING, March 30 (Xinhuanet) -- Although the evidence of prolonged longevity is slight, the U.S. Food and Drug Administration on Thursday ruled a new immune system treatment for advanced prostate cancer is safe and effective enough to be sold.

    Many experts said they were uneasy about backing Provenge, a vaccine-like treatment, because it showed only slight evidence it prolongs the lives of men with the disease. But most agreed to recommend approval anyway because of the scant options available to patients, many of whom are facing a terminal illness.

    "I wish we all could have voted 'maybe' on this, but I don't think we can," said Farshid Guilak, Ph.D., a professor of surgery at Duke University who was a member of the panel.

    Biotech firm Dendreaon Corp makes Provenge and claims the treatment is the first cellular therapy against cancer. To undergo treatment, patients have immune cells removed and treated with immune agents.

    The cells are then reintroduced into the body with chemical programming that, in theory, allows them to mount an immune response against cancer cells.

    Men with advanced prostate cancer often undergo hormone treatment used to block the action of testosterone and related hormones. The treatment can cause disturbing side effects, including breast enlargement and sexual dysfunction.

    A pair of studies suggested Provenge may slow by one to two weeks the progression of prostate cancer in men who have cancer that does not respond to hormone treatment.

    Men who used the treatment also showed some evidence of living longer than those who took a placebo. In one trial, men who got active treatment lived an average of 3.3 months longer. In another, they lived four and a half months longer.

    Experts criticized the studies for enrolling only roughly 100 to 130 patients, a relatively small number that can limit scientists' ability to interpret results.

    But most said they support Provenge anyway, given the limited choices for men with advanced disease.

    "If we can buy them a couple of minutes or a couple of months or a couple of years, then it's our obligation to do that," said Robert J. Samuels, a member of the panel who said he was diagnosed with prostate cancer 13 years ago. "We understand it's a risk. But it's a risk most of us are willing to take."

    Federal regulations compel the FDA to make a decision on the treatment by May 15. The agency isn't forced to follow advisory panels¡¯recommendations, but it usually does.

    (Agencies)