Fig. 2)

Biochemical progression-free survival (bPFS; 2a) and freedom from biochemical failure (FFBF; 2b) after high-dose radiotherapy (79.29 Gy) compared to lower-dose irradiation (71.43 Gy) in patients with locally advanced node-negative prostate carcinomas after prostatectomy who received PBRT-only or WPRT/PBRT. 93.6% of high-dose patients had positive margins and 97.3% of margin-positive patients had high-dose irradiation. Furthermore, 95.2% of patients with lower-dose radiotherapy had salvage treatment compared to 23.1% of patients with high-dose radiotherapy (p < 0.001). Therefore, the benefit in bPFS and FFBF cannot be assigned to either positive margins, higher doses or treatment indication as it is highly likely that all factors independently contributed to the better outcomes. A multivariate model could not be applied due to the high overlap of high-dose patients with positive margins. a Mean bPFS in the high-dose (mostly R1/postoperative) group was 64.4 months (95%-CI: 54.3–74.5 months; median: 75.7 months) and significantly longer (p < 0.001) compared to 32.2 months (95%-CI: 22.3–42.0 months; median: 21.4 months) in the low-dose (R0/salvage) group. b Mean FFBF in the high-dose (R1/postoperative) group was 66.1 months (95%-CI: 56.0–76.2 months; median: 75.7 months) and significantly longer (p < 0.001) compared to 33.4 months (95%-CI: 23.3–43.5 months; median: 21.4 months) in the low-dose (mostly R0/salvage) group