More patients with adverse pathologic characteristics after radical prostatectomy may benefit from adjuvant radiation therapy (ART) rather than early salvage radiation therapy (ESRT), according to researchers.
In a retrospective study, Jason Efstathiou, MD, DPhil, of Massachusetts General Hospital in Boston, and collaborators compared outcomes for 1566 patients (median age 60 years) who underwent ART or ESRT after prostatectomy due to pT3 and/or positive margins at 10 academic centers 1987 to 2013. By definition, 1195 patients with PSA levels below 0.1 ng/mL received ESRT and 371 with PSA of 0.1 to 0.5 ng/mL received ART. Median follow-up after surgery was roughly similar between groups after propensity score matching: 73.3 months ESRT vs 65.8 months ART.
Compared with ESRT, ART was associated with lower risks for biochemical recurrence, distant metastases, and death, according to results published in an online report from JAMA Oncology. Adjuvant RT was associated with significantly higher freedom from biochemical failure (12-year actuarial rates: 69% vs 43%); freedom from distant metastases (95% vs 85%); and overall survival (91% vs 79%).
On multivariate analysis, biochemical recurrence was less likely with ART, lower Gleason score and T stage, nodal irradiation, and postoperative androgen deprivation therapy. Use of pelvic nodal RT was similar between groups. To prevent 1 biochemical failure, 6 to 12 patients would need to be treated with ART compared with ESRT, given a nomogram-based surgical cure rate, according to the investigators.
“The current use of ART in high-risk patients is less than 10%,” Dr Efstathiou and his colleagues stated. “Our findings suggest that a greater proportion of such men may benefit from ART, especially those for whom the estimated risk of postprostatectomy recurrence is greater than 50%.”
The dose of radiation for ESRD was a median 66 Gy, which is associated with decreased risk for biochemical failure. The researchers acknowledged that higher doses might reduce the advantages observed with ART.
Among the study’s limitations, the team acknowledged an inherent selection bias for treatment and the slightly longer follow-up in the ESRT group. Data from current randomized trials should clarify relative risks and benefits.
Hwang WL, Tendulkar RD, Niemierko A, et al. Comparison between adjuvant and early-salvage postprostatectomy radiotherapy for prostate cancer with adverse pathological features. JAMA Oncol. doi:10.1001/jamaoncol.2017.5230 [Published online January 25, 2018]