Providing radiation therapy to men with rising prostate-specific antigen (PSA) levels following radical prostatectomy, or salvage radiotherapy (SRT), can reduce the risk of dying from prostate cancer by more than 60 percent, with the greatest benefit seen in men with rapidly rising PSA levels, according to an analysis presented at the first Genitourinary Cancers Symposium, held this week in San Francisco.
Researchers at Johns Hopkins University School of Medicine, lead by Bruce Trock, MD, found that the benefits of SRT appear to persist even when it is given up to two years after PSA levels begin to rise.
“These findings are the first to support the effectiveness of SRT for improving survival in men with recurrent prostate cancer,” said Trock, associate professor of urology, epidemiology, oncology and environmental health sciences at Johns Hopkins. “If validated, these results suggest that for high-risk prostate cancer, radiotherapy should be given promptly when there is evidence for recurrence after radical prostatectomy, as early salvage radiotherapy may improve overall survival.”
The study investigators compared prostate cancer-specific survival among men with rising PSA levels after radical prostatectomy (biochemical recurrence).
Of the men, the researchers found that 160 patients had received SRT alone, 78 received SRT plus hormonal therapy and 397 received no SRT or hormonal therapy. Trock noted that the study was not a prospective randomized clinical trial, but a retrospective analysis of men who had already been treated.
After 10 years, 86 percent of men in the SRT group and 82 percent of men in the SRT/hormonal therapy group had not died from prostate cancer, versus 62 percent of men who received no salvage therapy, the authors wrote. The results did not change after taking into account individual patient characteristics associated with prognosis, according to the researchers.
The investigators also found that SRT had to be given soon after recurrence – prostate cancer-specific survival improved only when SRT was given less than two years after biochemical recurrence.
The impact of SRT was particularly strong in men whose PSA levels doubled in less than six months (an indicator of more aggressive disease); SRT reduced the risk of prostate cancer death in these men by 86 percent, the researchers said.
The authors noted that SRT did not significantly reduce the risk of death among men whose PSA levels doubled in six months or more, due to the fact that the men had less aggressive disease and may have fared well even without radiation therapy.
Trock and colleagues cautioned that despite evidence that SRT appears to improve survival, confirmation is needed in other comparable groups of men, and a randomized clinical trial will ultimately be needed to determine the impact of SRT on survival.