Randomised Trial of Adjuvant Radiotherapy Following Radical Prostatectomy Versus Radical Prostatectomy Alone in Prostate Cancer Patients with Positive Margins or Extracapsular Extension

Abstract

Background: It remains unclear whether patients with positive surgical margins or extracapsular extension benefit from adjuvant radiotherapy following radical prostatectomy.

Objective: To compare the effectiveness and tolerability of adjuvant radiotherapy following radical prostatectomy.

Design, setting, and participants: This was a randomised, open-label, parallel-group trial. A total of 250 patients were enrolled between April 2004 and October 2012 in eight Finnish hospitals, with pT2 with positive margins or pT3a, pN0, M0 cancer without seminal vesicle invasion.

Intervention: A total of 126 patients received adjuvant radiotherapy at 66.6Gy.

Outcome measurements and statistical analysis: The primary endpoint was biochemical recurrence-free survival, which we analysed using the Kaplan-Meier method and Cox proportional hazard regression. Overall survival, cancer-specific survival, local recurrence, and adverse events were secondary endpoints.

Results and limitations: The median follow-up time for patients who were alive when the follow-up ended was 9.3yr in the adjuvant group and 8.6yr in the observation group. The 10-yr survival for biochemical recurrence was 82% in the adjuvant group and 61% in the observation group (hazard ratio [HR] 0.26 [95% confidence interval {CI} 0.14-0.48], p<0.001), and for overall survival 92% and 87%, respectively (HR 0.69 [95% CI 0.29-1.60], p=0.4). Two and four metastatic cancers occurred, respectively. Out of the 43 patients with biochemical recurrence in the observation group, 37 patients received salvage radiotherapy. In the adjuvant group, 56% experienced grade 3 adverse events, versus 40% in the observation group (p=0.016). Only one grade 4 adverse event occurred (adjuvant group). A limitation of this study was the number of patients.

Conclusions: Adjuvant radiotherapy following radical prostatectomy is generally well tolerated and prolongs biochemical recurrence-free survival compared with radical prostatectomy alone in patients with positive margins or extracapsular extension.

Patient summary: Radiotherapy given immediately after prostate cancer surgery prolongs prostate-specific antigen progression-free survival, but causes more adverse events, when compared with surgery alone.

Keywords: Adjuvant radiotherapy; Extracapsular extension; Positive margins; Prostate cancer; Radical prostatectomy.