Research on Prophylactic Pelvic Irradiation for Prostate Cancer

In a recently published research, it has been highlighted that prophylactic pelvic irradiation for high-risk, locally advanced prostate cancer improved biochemical failure-free survival (BFFS) and disease-free survival (DFS) as compared with prostate-only radiotherapy (PORT), but overall survival (OS) did not appear to differ.

The research findings have been published in the Journal of Clinical Oncology.

Researchers recently sought to address the longstanding question regarding the efficacy of prophylactic pelvic nodal irradiation in high-risk prostate cancer. The present trial incorporates the contemporary standards of staging, radiotherapy dose, technique, nodal volumes, and duration of androgen deprivation therapy.

Study Design

This was a phase III, single-center, randomized controlled trial that enrolled eligible patients undergoing radical radiotherapy for node-negative prostate adenocarcinoma, with estimated nodal risk ≥ 20%. Randomization was 1:1 to PORT (68 Gy/25# to prostate) or whole-pelvic radiotherapy (WPRT, 68 Gy/25# to prostate, 50 Gy/25# to pelvic nodes, including common iliac) using computerized stratified block randomization, stratified by Gleason score, type of androgen deprivation, prostate-specific antigen at diagnosis, and prior transurethral resection of the prostate.

All patients received image-guided, intensity-modulated radiotherapy and a minimum of 2 years of androgen deprivation therapy. The primary endpoint was 5-year biochemical failure-free survival (BFFS), and secondary endpoints were disease-free survival (DFS) and overall survival (OS).

Data Analysis

Data analysis revealed the following facts:

• From November 2011 to August 2017, a total of 224 patients were randomly assigned (PORT = 114, WPRT = 110).
• At a median follow-up of 68 months, 36 biochemical failures (PORT = 25, WPRT = 7) and 24 deaths (PORT = 13, WPRT = 11) were recorded.
• Five-year BFFS was 95.0% (95% CI, 88.4 to 97.9) with WPRT versus 81.2% (95% CI, 71.6 to 87.8) with PORT, with an unadjusted hazard ratio (HR) of 0.23 (95% CI, 0.10 to 0.52; P < .0001).
• WPRT also showed higher 5-year DFS (89.5% vs. 77.2%; HR, 0.40; 95% CI, 0.22 to 0.73; P = .002), but 5-year OS did not appear to differ (92.5% vs. 90.8%; HR, 0.92; 95% CI, 0.41 to 2.05; P = .83).
• Distant metastasis-free survival was also higher with WPRT (95.9% vs. 89.2%; HR, 0.35; 95% CI, 0.15 to 0.82; P = .01).
• Benefit in BFFS and DFS was maintained across prognostic subgroups.

Observing the results, the research team noted that "Prophylactic pelvic radiotherapy resulted in significantly improved biochemical failure-free survival and disease-free survival as compared with prostate-only radiotherapy. Modest increase was observed in the incidence of grade ≥ 2 late genitourinary toxicity with pelvic radiotherapy, with low incidence of GI toxicity in both the arms."

Prophylactic pelvic radiotherapy resulted in significantly improved biochemical failure-free survival and disease-free survival as compared with prostate-only radiotherapy.

For the full article, follow the link: 10.1200/JCO.20.03282

Primary source: Journal of Clinical Oncology