Purpose: This study examines the effect of adjuvant radiation therapy (RT) on outcome in patients with pT3N0 prostate cancer and makes comparisons to a matched control group.
Methods and materials: At our center, 149 patients undergoing radical prostatectomy were found to have pT3N0 prostate cancer, had an undetectable postoperative prostate-specific antigen (PSA) level, and had no immediate hormonal therapy. Fifty-two patients received adjuvant RT within 3 to 6 months of surgery. Ninety-seven underwent radical prostatectomy alone and were observed until PSA failure. From these two cohorts, we matched patients 1:1 according to preoperative PSA (<10 ng/ml vs. >10 ng/ml), Gleason score (<7 vs. > or =7), seminal vesicle invasion, and surgical margin status. Seventy-two patients (36 pairs) were included in the analysis. Median follow-up time was 41 months. We calculated a matched-pairs risk ratio for cumulative risk of PSA relapse (a rise above 0.2 ng/ml).
Results: After controlling for the prognostic factors by matching, there was an 88% reduction (95% confidence interval [CI]: 78-93%) in the risk of PSA relapse associated with adjuvant RT. The 5-year freedom from PSA relapse rate was 89% (95% CI: 76-100%) for patients receiving adjuvant RT as compared to 55% (95% CI: 34-79%) for those undergoing radical prostatectomy alone.
Conclusions: These data suggest that adjuvant RT for pT3N0 prostate cancer may significantly reduce the risk of PSA failure as compared to radical prostatectomy alone. Its effect on clinical outcome awaits further follow-up.