THURSDAY, July 11, 2002 (HealthDayNews) -- Adding testosterone-suppressing treatments to radiation therapy can keep men with prostate tumors alive and cancer-free longer than radiation alone, a study has found.
Combining the two therapies at the beginning of treatment led to a 16 percent greater survival rate over slightly more than a five-year period, according to the study. That means 16 more men out of 100 with the disease lived through it if they received the two therapies compared to radiation only.
An earlier version of the findings, which are reported this week in The Lancet by an international team of researchers, helped set the standard of care for men with locally advanced prostate cancer. In these men, the main tumor has left the gland but not migrated far into the body.
"What we're looking at is a remarkable survival benefit," says Dr. Padraig Warde, a radiation oncologist at the University of Toronto's Princess Margaret Hospital, and a co-author of the study. Considering the more modest success rates of treatments for other cancers, the effect of adding hormone therapy to radiation is "huge," he says.
Some 180,000 American men each year are diagnosed with prostate cancer. Of those, about 15 percent are candidates for hormone-suppressing drugs plus radiation, Warde says.
So-called anti-androgen treatments suppress testosterone, the male sex hormone that stimulates prostate cell growth. Although effective, the therapy leads to a host of unpleasant side effects, including impotence, hot flashes, lethargy and osteoporosis, which complicate the decision to take it.
Warde and his colleagues followed 412 men with aggressive prostate cancer that hadn't spread widely throughout the body but had left the gland.
All the men, whose average age was 71, were dosed with beams of radiation therapy to kill the cancer cells, and half were also given regular injections of the anti-androgen drug goserelin.
Goserelin is a luteinizing hormone-releasing hormone (LHRH) agonist that blocks the testicles from producing testosterone. AstraZeneca, which markets the drug as Zoladex, provided it to the researchers.
The injections began at the same time as the radiation, but lasted three years instead of the seven weeks for the radiation therapy.
The researchers tracked the men for an average of 5.5 years. During that time, three-quarters of those who received both the hormone treatments and radiation had no signs of returning cancer, compared with 40 percent of the men who got radiation alone. The number with distant metastases was also considerably lower in the combination group -- 10 percent vs. 29 percent.
The overall survival rate was higher in the combination therapy group, too -- 78 percent vs. 62 percent. And there were far fewer deaths attributed to prostate cancer -- 42 vs. 12, the researchers say.
The researchers note that the method of radiation they used wasn't the most modern form of the treatment, which now lets doctors direct higher doses to a more concentrated area of tumor tissue.
Dr. Ralph de Vere White, director of the cancer center at the University of California, Davis, says the study supports the recommendation that men with localized but advanced prostate tumors receive hormone-blocking treatment while undergoing radiation.
However, he adds, what remains unanswered is how long they should take the drugs and how, exactly, the medication is helping. It's possible, for example, that hormone suppression simply augments radiation while that treatment is ongoing. If that's the case, perhaps the two therapies can be stopped at the same time.
But if, as the latest study suggests, squelching testosterone prevents prostate cancer from spreading, patients may do better by taking it well beyond the end of radiation. At this point, "it's very hard to separate out," de Vere White says.
Warde is now running a study comparing radiation plus hormone-suppressing therapy and hormone treatments alone to address that very question. The study will ultimately include more than 650 men with locally advanced prostate cancer.
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