postate-cancer

Prostate-Only Versus Whole-Pelvic Radiation Therapy in High-Risk and Very High-Risk Prostate Cancer (POP-RT): Outcomes from Phase III Randomized Controlled Trial

In the March 8, 2021 edition of Journal of Clinical Oncology, investigators report on the results of the POP-RT trial.  

Purpose

The purpose of the study was to assess the clinical outcomes in a randomized fashion, of whole pelvic radiotherapy versus prostate only radiotherapy for patients with high risk prostate cancer. A single center phase 3 randomized clinical trial was performed for eligible patients who underwent radical radiotherapy for node-negative prostate adenocarcinoma, with an estimated node risk of at least 20%. 

Methods

Patients underwent a one-to-one randomization to prostate only radiotherapy, 68 Gray over 25 fractions to the prostate for whole pelvic radiotherapy, 68 Gy over 25 fractions to the prostate and 50 Gray over 25 fractions to the pelvic nodes which included the common iliac lymph nodes.  Patients were stratified via Gleason score, PSA at the time of diagnosis, prior transurethral resection of the prostate and the different types of androgen deprivation therapy utilized.  All patients received a image guided, intensity modulated RT and at least 2 years of androgen deprivation therapy.  5-year biochemical free survival, was the primary endpoint and overall survival along with disease-free survival were secondary endpoints.

Results

224 patients were randomized, 114 to the prostate only arm and 110 to the whole prostate arm.  After median follow-up of 68 months, there were 36 biochemical failures, 25 and the prostate only arm and 7 in the whole pelvic arm.  There were 24 Dexcom 13 in the prostate on the arm and 11 in the whole pelvic arm.  The 5-year biochemical failure free survival was 95%, 95% confidence interval, 88.4–97.9 with whole pelvic radiotherapy versus 81.2%, 95% confidence interval, 71.6–87.8, with prostate only radiotherapy, with a hazard ratio that was unadjusted of 0.23 (95% CI, 0.10 to 0.52; P < .0001).  The 5-year disease-free survival was higher with whole pelvic radiotherapy,(89.5% v 77.2%; HR, 0.40; 95% CI, 0.22 to 0.73; P = .002), but there was no difference in the 5-year overall survival,(92.5% v 90.8%; HR, 0.92; 95% CI, 0.41 to 2.05; P = .83).  Distant metastasis free survival was higher in the whole pelvic arm,(95.9% v 89.2%; HR, 0.35; 95% CI, 0.15 to 0.82; P = .01). Benefit in BFFS and DFS was maintained across prognostic subgroups, per the investigators.

Conclusion

The authors concluded “Prophylactic pelvic irradiation for high-risk, locally advanced prostate cancer improved BFFS and DFS as compared with PORT, but OS did not appear to differ.”

Reference:

Prostate-Only Versus Whole-Pelvic Radiation Therapy in High-Risk and Very High-Risk Prostate Cancer (POP-RT): Outcomes from Phase III Randomized Controlled Trial

https://ascopubs.org/doi/full/10.1200/JCO.20.03282

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