Men With Prostate Cancer After Surgery May Benefit From Shorter Duration of Radiation Therapy

Hypofractionated radiation for nearly five weeks in men with prostate cancer after surgery may have similar results without added side effects compared with radiation therapy for a standard duration of seven weeks.

A shorter but increased course of radiation may not increase long-term side effects or negatively impact quality of life compared with conventional radiation therapy in men with prostate cancer after undergoing prostate removal surgery, study results demonstrated.

Results from the study were recently presented at the American Society for Radiation Oncology Annual Meeting.

“It’s really all about reducing the burden of prostate cancer on society,” said Dr. Mark K. Buyyounouski, professor of radiation oncology (radiation therapy) and director of genitourinary cancers at Stanford University in California, in an interview with CURE®. “For patients, we want to be able to provide them greater access to post-prostatectomy radiotherapy because it’s potentially curative, but it’s underutilized.”

Researchers assessed side effects in 296 patients who either underwent hypofractionated (when radiation doses are divided into larger doses and administered over a shorter amount of time) radiation after surgery (144 patients) or conventional radiation after surgery (152 patients).

Buyyounouski explained that a longer duration of radiation in these patients typically involves treatment Monday through Friday for seven weeks. In contrast, hypofractionated radiation minimizes that time requirement by approximately two-and-a-half weeks.

“What that means is it’s a shorter time commitment,” he said. “They have less expenses relating to travel and copays, and they have fewer absences maybe from work, from family responsibilities or other responsibilities. If we can lower the barriers to people signing on to go back and forth and get radiation at a radiation center, great.”

The main focus of this study was to observe any impact on gastrointestinal or genitourinary toxicity throughout the course of radiation that patients were assigned.

Patients assigned hypofractionated or conventional radiation after surgery had similar scores related to genitourinary toxicity after radiation, at six months and 12 months. For gastrointestinal toxicity, scores were significantly different between both groups after completing radiation, which leveled out at six months and 12 months.

“It’s not a surprise,” Buyyounouski said about the gastrointestinal toxicity results. “Bowel toxicity is usual and expected after prostate radiation because the rectum is the dose-limiting structure. We always counsel patients that they are going to experience bowel changes over the course of treatment that peak at the end of treatment.”

Buyyounouski added that these results also indicate that these short-term side effects tend to resolve themselves over time.

“When (we) talk to patients about undergoing the treatment, whether it’s surgery, radiation or anything, everyone expects that there could be some short-term side effects,” he said. “What they’re really concerned about is, is it going to go away? What (these) data (tell) us reassuringly is, yes, it’s going to go away. And you’re going to be sitting in the same place as if you had the longer (duration of radiation) when it’s all said and done.”

Of note, there were no significant differences related to genitourinary and gastrointestinal toxicities in patients assigned either hypofractionated or conventional radiation.

After a median follow-up of 2.1 years, differences were not observed in both groups for biochemical failure (an increase in prostate-specific antigen in patients after radiation treatment, which may indicate that the cancer has returned) or local failure (when the cancer persists or reappears at the primary tumor location).

“The reason we were interested in monitoring recurrence was to see if there was a signal that there is a difference in how well the treatment works,” Buyyounouski said. “At two years, there doesn’t appear to be any obvious signal, and that’s not surprising because we’re still talking about prostate cancer. The response to radiation shouldn’t matter whether you’ve had surgery or haven’t had surgery.”

Buyyounouski mentioned that he believes that oncologists may be more inclined to give their patients a shorter, stronger course of radiation compared with what was administered before.

“The study results reassure people that there’s no obvious dangers in terms of toxicity,” Buyyounouski said. “There’s no obvious detriment in terms of how well it works and its success rate. I predict that there will be a rather rapid acceptances into everyday practice.”

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