THURSDAY, Oct. 6, 2005 (HealthDay News) -- For men with advanced prostate cancer confined to the prostate, radiation treatment along with a six-month program of androgen (male hormone) deprivation therapy can improve survival by as much as 50 percent, researchers report.
Androgen deprivation therapy lowers concentrations of testosterone, which experts have long recognized as a powerful stimulator of prostate cancer cell growth.
Although hormone therapy is now standard treatment for metastatic prostate cancer, whether it is beneficial in treating prostate cancer still confined to the organ has been less clear. Also unclear was whether short-term hormone therapy might be effective -- most patients now receive the treatment over a period of at least three years.
"Finding that we can stop cancerous progression in 40 percent of men by just six months of testosterone suppression treatment with minimal side effects is enormously important," said study author Dr. Jim Denham, from the Trans-Tasman Radiation Oncology Group and University of Newcastle, New South Wales, Australia.
In their study, Denham's team randomly assigned 818 men with locally advanced prostate cancer to radiation treatment with no testosterone suppression, or three months or six months of testosterone suppression.
Reporting in the Oct. 6 early online edition of The Lancet Oncology, the Australian team found that men treated with three months of hormone therapy before and during radiation were at a 35 percent lower risk of relapse compared to men receiving radiation alone. For men treated with six months of hormone therapy before and during radiation, that risk of relapse was reduced by 44 percent.
In addition, survival among men receiving both radiation and hormone treatment was 54 percent better compared with men who received radiation alone, according to the report.
Radiation therapy has also changed for the better since this study was conducted, Denham noted.
"Technical improvements in radiotherapy equipment in the last 10 years will also improve treatment results," he said. "Our new trial, which is known as the RADAR trial, is testing the new radiotherapy equipment, as well as determining whether an additional year of testosterone suppression can produce further benefits in those men at greatest risk".
One expert said these findings support a shorter course of hormone therapy.
"This is an important study, validating a [previous] study we published in 2004 that showed that six months of hormonal therapy and radiation improves cancer-specific survival compared with no hormonal therapy," said Dr. Anthony D'Amico, a Harvard researcher and chief of radiation oncology at Brigham and Women's Hospital in Boston. Overall survival has not been affected, but this may be due to other causes of death among men in the study, he added.
"Whether three years of hormonal therapy should still be standard is questioned by the current study and ours, and will be answered definitively by the large randomized study of three years verses six months of hormonal therapy, the results of which are soon to be released," D'Amico said.
However, another expert questioned whether the findings apply to the radiation therapy patients typically receive today.
"It's an interesting result," said Dr. Stephen J. Freedland, an assistant professor of urology at Duke University School of Medicine. "The question is how applicable is it to your average patient today with prostate cancer?"
"I'm not sure it applies to most men today," he said. For one thing, the dose of radiation used in the study is lower than what patients currently receive, Freedland noted.
Androgen deprivation therapy may be making up for less-than-optimal radiation therapy, Freedland said. "If we give higher-dose radiation, do we need to do androgen deprivation therapy?" he asked.
Furthermore, Freedland believes the patients in the study had more advanced cancers than are commonly seen in prostate cancer patients today. "So if you take men who have low-risk disease, do these studies, observations really apply? We don't know the answer to that."
Patients who consult a radiation therapist regarding treatment for prostate cancer should ask about hormone therapy, Freedland advised. "The question to ask your radiation oncologist is: Am I one of those people who stand to benefit from hormone therapy?"
The National Cancer Institute can tell you more about prostate cancer.