Radiotherapy May Help in Node-Positive Prostate Cancer

By David Douglas

December 02, 2015

NEW YORK (Reuters Health) - Adding prostate and pelvic radiotherapy (RT) to hormone therapy appears to cut relapse rates in men newly diagnosed with high-risk nonmetastatic (M0) node-positive prostate cancer, according to an exploratory analysis by European investigators.

In a November 25 online paper in JAMA Oncology, Dr. Nicholas D. James of the University of Warwick, Coventry, UK, and colleagues note that they came to this conclusion using data collected between 2005 and 2014 in 721 patients allocated to the control arm (standard-of-care only) of the STAMPEDE Trial.

Dr. James told Reuters Health by email that these data "form part of a pair of publications detailing outcomes in the control arm of STAMPEDE and help to make sense of the forthcoming paper on the randomized comparisons currently in press at The Lancet."

"Within the trial," he continued, "RT was optional until 2011 for high-risk node-negative M0 patients after which it became mandatory. For node-positive M0 patients RT was optional throughout."

"This," he continued, "allowed us to do a multivariate analysis of the effect of RT on time to relapse (there were insufficient events to look at survival). Prostate RT reduced relapse rates at three years by 67%, mirroring the published randomized data. In the node-positive subgroup the rate of relapse was reduced by 52%, strongly supporting its use in this setting where there are currently no randomized studies."

Overall, failure-free survival outcomes favored planned use of RT for patients with both node-negative (hazard ratio 0.33) and node-positive disease (HR, 0.48).

Commenting on the findings by email, Dr. Anthony V. D' Amico, author of an accompanying editorial, told Reuters Health that although the findings may "probably" be true, such outcome "cannot be rigorously concluded due to the short median follow-up, low event rate, nonrandomized data, and lack of adjustment for treatment variation and some known prostate cancer prognostic factors."

Nevertheless, Dr. D' Amico, of Brigham and Women's Hospital, Boston, points out in his editorial that "although no level 1 evidence exists to make a recommendation for the use of external beam RT for all men with node-positive prostate cancer, consideration of the totality of the evidence suggests that some select men may benefit."

Among these are "otherwise healthy men with no or minimal comorbidity who could live long enough to permit the locoregional control benefit afforded by pelvic RT to translate into a survival benefit." The approach "could also be of use in some men who have a minimal risk of harboring occult microscopic disease beyond the pelvis that is already castration resistant and not sensitive to currently available therapies."

A number of organizations and companies supported this research. The authors reported no disclosures.

SOURCE: http://bit.ly/1PWoQwC and http://bit.ly/1LJ6k34

JAMA Oncol 2015.

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