Just six months of hormone therapy, along with radiation, cuts the risk of dying from locally advanced prostate cancer in half when compared with radiation alone, researchers report.
Just as important, the study indicates that a short course of hormone therapy has few of the side effects seen with longer treatment regimens of two to three years.
Hormone therapy in men, also known as androgen-deprivation therapy, lowers levels of the male hormones that encourage prostate cancer to grow.
"A halving of the risk of dying from these more advanced prostate cancers clearly has very major significance for men affected," said researcher David Lamb, MB, FRCP, director of the Prostate Cancer Trials Unit at the University of Otago in Wellington, New Zealand.
"Early diagnosis of prostate cancer remains the goal, but at least men presenting with more advanced tumors can now be offered treatment proven to have a much better chance of cure," he said.
The report was published in an online edition of The Lancet Oncology.
As part of the Trans-Tasman Radiation Oncology Group trial, Dr. Lamb's group randomly assigned 802 men with locally advanced prostate cancer to radiation alone, or three months of hormone therapy plus radiation, or six months of hormone therapy and radiation.
Over an average of 10.6 years of follow-up, men who received six months of hormone therapy and radiation were significantly less likely to die from prostate cancer than men who had radiation alone-11% vs. 22%, respectively. They were also much less likely to die from any cause-29% vs. 43%, the researchers found.
Hormone therapy over three months had no effect on the spread of prostate cancer, or dying from the cancer or any other cause, compared with radiation alone, Lamb's team noted.
Compared with a six-month bout of the hormone therapy, androgen-deprivation therapy over an extended period can result in serious side effects, including erectile dysfunction, hot flashes, fatigue, osteoporosis, high cholesterol, anemia and cardiac death.
"This study with locally advanced prostate cancers has shown that adding ljust six months of hormone treatment to radiotherapy halves the numbers of deaths from prostate cancer in the next 10 years," Dr. Lamb said.
"Whilst there were already known to be benefits from short-term hormone treatment in this group of patients, this is the first trial to demonstrate the magnitude of long-term benefits. A 50% improvement in survival is a massive gain, and it was achieved with relatively few extra side effects for patients," he added.
Prostate cancer expert Anthony V. D'Amico, MD, PhD, chief of radiation oncology at Brigham and Women's Hospital in Boston, said this study validates his own research, which showed that six months of hormone therapy plus radiation prolonged survival.
"You get an overall survival benefit when you add six months of hormone therapy to radiation in men with high-risk prostate cancer," he said. "Six months of hormonal therapy with radiation is a valid treatment option with high-risk prostate cancer.
Men may choose to have longer hormone treatment, Dr. D'Amico said. However, survival will probably only marginally improve, and there is a risk for heart problems with the prolonged use of hormone therapy, he said.