Radiotherapy after radical prostatectomy for adenocarcinoma of the prostate: a UK institutional experience and review of published studies

Aims: The role of radiotherapy to the prostate bed after radical prostatectomy is the subject of much debate. We carried out a retrospective analysis of all patients treated with either adjuvant radiotherapy (ART) or salvage radiotherapy (SRT) in a single UK cancer centre and compared outcomes with published studies. Materials and methods: All patients receiving radiotherapy at any time after a radical prostatectomy were identified and data collected. Patients were referred for ART because of positive surgical margins. SRT was carried out in patients with a detectable or rising prostate-specific antigen (PSA) postoperatively. Patients received either 55 Gy in 20 fractions or 60-64 Gy in 30-32 fractions. All but eight patients were treated using three-dimensional conformal radiotherapy. Both groups were combined for statistical analysis. Biochemical progression -free survival (BPFS) was calculated and displayed using Kaplan-Meier curves. Cox regression was used for univariate and multivariate analysis. Results: In total, 40 patients received postoperative radiotherapy and had a 3-year overall BPFS of 64%. There was no significant difference in 3-year BPFS between ART and SRT (73% vs 61%, P = 0.33). Univariate analysis showed that 3-year BPFS was significantly longer if the highest postoperative PSA was < 0.5 ng/ml compared with 0.5 ng/ml (83% vs 47%, P = 0.019), and if the Gleason grade was < 7 compared with < 7 (92% vs 49%, P = 0.007). A PSA at diagnosis < 10 ng/ml, positive surgical margins, absence of seminal vesicle involvement and neoadjuvant hormones were all associated with a trend towards improved BPFS. Patients with all of these factors had a 3-year BPFS of 91%. Multivariate analysis of the same parameters showed that only Gleason grade remained statistically significant (P = 0.019). Conclusions: The results from this series are in line with published studies, and support the evidence that prostate bed radiotherapy may affect biochemical control in a proportion of patients at risk of relapse. It is not clear whether ART in patients at high risk of relapse or SRT on relapse is most effective.