Added to hormone therapy, it benefited men with locally advanced tumors.

BOSTON—Men with locally advanced prostate cancer can reduce their risk of dying from the malignancy by adding radiation treatment to anti-androgen therapy, according to a study that researchers believe to be the first of its kind.

The finding is based on data from 875 men with locally advanced prostate cancer who participated in a randomized phase 3 trial. After receiving total androgen block for three months, the men were assigned to continued treatment with anti-androgen therapy alone or in combination with radiotherapy. During a median follow-up of 7.5 years, 132 (30%) of the 439 men receiving anti-androgen therapy alone died compared with 94 (21.6%) of the 436 men in the combination-treatment arm.

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The investigators observed PSA recurrence in 285 patients (65%) in the anti-androgen group compared with only 77 (17.5%) in the combination arm. In addition, 18% of patients who underwent hormone therapy alone died of prostate cancer compared with only 9% of those who had both hormone therapy and radiation.

“This randomized trial is the first to show that men with locally advanced prostate cancer will survive substantially longer when radiation is added to their treatment plan,” said lead investigator Anders Widmark, MD, a professor in the department of radiation oncology at Umea University in Umea, Sweden. He reported study findings here at the American Society for Therapeutic Radiology and Oncology annual meeting,

“I was a bit surprised that there was such a large benefit,” Dr. Widmark told Renal & Urology News.  “In Scandinavia, we are more conservative, but this shows everyone should [be offered] both treatments. Many patients are already given both therapies, but this study shows that the benefits are greater than we thought in the past. It also shows that hormones alone are not enough.”

Four years after treatment, moderate-to-severe urinary leakage and pain during urination were more common in the combined treatment group than the monotherapy arm (6% vs. 3% and 4% vs. 2%, respectively).  

Investigators reported that erectile dysfunction occurred more frequently in the combined treatment group (89%) than the anti-androgen group (81%). The proportions of men reporting little or no sexual desire were similar in both groups (55% and 59% for the combined treatment and monotherapy arms, respectively).

Quality of life four years after treatment was similar between the two groups, except for decreased social functioning in the patients who had the combined treatment.

“There is a hypothesis that these two therapies work synergistically,” Dr. Widmark explained. “Radiation, by killing the cells, might make it easier for the immune system to attack the cancer cells. It is tempting to think so but we really don’t know.  Maybe radiation increases an immunologic response that hinders progression of the tumors.”