Nov. 3, 2009 (Chicago) -- The majority of men with prostate cancer can be spared anti-hormone therapy -- and all of its side effects, including impotence, hot flashes, and liver problems, researchers say.
Adding a short course of hormone-blocking therapy to radiation treatment extended the lives of medium-risk prostate cancer patients but offered no benefit to low-risk patients when compared to radiation alone, according to the largest study of its kind.
"Our findings show that men with intermediate-risk disease, which is a significant minority of patients, gain a benefit in overall survival from the addition of four months of hormone therapy," says Christopher U. Jones, MD, of Radiological Associates of Sacramento in Sacramento, Calif.
"Equally importantly, men with low-risk disease, which is the vast majority of prostate cancer patients, have little to gain from hormone therapy, so they can avoid all the additional toxicities that come with it," he tells WebMD.
The findings were presented at the annual meeting of the American Society for Radiation Oncology (ASTRO).
Hormone-Blocking Drugs for Prostate Cancer Became Routine in 1990s
Prostate cancer is the most common type of cancer in men besides skin cancer, accounting for about one in four of all new cancer cases diagnosed in men each year. The tumors grow in an environment of the hormone testosterone, and anti-hormone treatments block testosterone.
Patients are categorized as being low, intermediate, or high risk depending on such factors as levels of PSA, or prostate-specific antigen, and Gleason score, a measure of the aggressiveness of the disease.
About 70% of men with prostate cancer in the U.S. have early, low-risk disease. Another 15% have medium-risk disease, and the rest have high-risk disease.
Doctors began routinely offering anti-hormone treatment to prostate cancer patients after a large study in the 1990s showed that giving a short course of hormone-blockers after radiation extended the lives of men with advanced prostate cancer compared to radiation alone.
"The results were seized upon by radiation oncologists, who assumed that if hormone therapy is good for nasty cancers, it is probably pretty good for lower-risk cancers, too," says incoming ASTRO president Anthony Zietman, MD, of Harvard Medical School.
By the end of decade, concerns about the long-term consequences of the drugs arose, and doctors began to question whether the benefits outweighed the risk in lower-risk patients, says Zietman, who was not involved with the research.
Hormone-Blocking Drugs Don't Benefit Low-Risk Prostate Cancer Patients
To settle the issue, Jones and colleagues randomly assigned about 2,000 men with low- and intermediate-risk prostate cancer to radiation plus anti-hormone drugs or radiation alone.
Eight years later, 72% of patients with intermediate-risk cancer who got the hormone-blocking drugs were still alive, compared with only 66% of radiation alone.
Among patients with low-risk cancer, however, about three-fourths were alive eight years later -- regardless of whether they got hormone-blocking drugs.
Looked at another way, "only 1% of men in the low-risk group died of their prostate cancer no matter what treatment they got. Among men with intermediate-risk cancer, 8% given radiation alone died of their cancer compared with only 2% who got anti-hormone drugs," Jones says.
Outgoing ASTRO president Tim R. Williams, MD, a private practitioner in Boca Raton, Fla., tells WebMD that "this is the best data we have and it really clarifies who does and who does not need hormone therapy after radiation."
Because the men in the study were treated about a decade ago, the techniques used to deliver radiation have changed, Jones says.
"The question now is, with modern radiation therapy, which is higher dose, will hormone therapy still benefit the intermediate risk patients?" he says. Researchers are enrolling men in a large trial to study that question.