The overall median follow-up was 63.5 months. The 5-year BCR-free survival rate was 58.2% for the cohort overall and 76.2% for the 118 patients 55.7% who had early salvage RT, defined as RT started when the PSA level was 0.5 ng/mL or less, the investigators reported online in PLoS One
When patients have a PSA that rises over 0.1 after robotic prostatectomy, they likely have recurrent prostate cancer somewhere. This study shows that patients treated with salvage XRT (external beam radiotherapy) had better results if the treatment was started below a PSA of 0.5.
Personally, in the patients who are good candidates for salvage XRT, I prefer to start the radiation after the PSA goes higher than 0.2 and sometimes lower.