Patients at high risk of progression after radical prostatectomy: do they all benefit from immediate post-operative irradiation? (EORTC trial 22911)

EORTC trial 22911 demonstrated that immediate postoperative irradiation significantly improved biochemical failure free survival (BPFS) compared to wait-and-see (W and S) until relapse in patients with pT2-3 tumours and pathological risk factors after radical prostatectomy. In this study, we have investigated the heterogeneity of the treatment benefit across defined subgroups of patients. Data from 972 patients were used. A risk model was developed in the W and S group and the Log-rank test for heterogeneity was applied (alpha=0.05). Positive surgical margin (SM+), seminal vesicle invasion (SV+), WHO differentiation grade, pre- and post-operative PSA were independent predictors for BPFS in the W and S group. Men with SV+ were at higher risk of relapse whereas those with SM+ but no capsule infiltration (ECE-) did not seem to differ from those with SM-ECE+ or with SM+ECE+. Postoperative irradiation improved biochemical progression-free survival in all patient groups. Longer follow-up is needed to assess the endpoint of clinical progression-free survival