High-dose salvage intensity-modulated radiotherapy (HD-SIMRT) can be used safely for men with rising PSA after radical prostatectomy (RP) for prostate cancer, with good results in terms of biochemical relapse-free survival (bRFS), according to researchers.
Salvage radiotherapy is the only therapeutic option offering potential cure for men with PSA relapse after RP, the investigators noted, but long-term bRFS is poor, with fewer than 50% of patients remaining without evidence of disease after five years when treated with conventional radiation doses.
Piet Ost, MD, of Ghent University Hospital in Belgium, and colleagues examined late toxicity and outcomes among 136 patients treated with HD-SIMRT (up to 76 Gy), with or without androgen deprivation therapy (ADT), because of persisting or rising PSA following RP. A median 76 Gy dose (range 70-70 Gy) was administered to the RP bed.
Men were started on ADT on the basis of seminal vesicle invasion, pre-prostatectomy PSA levels greater than 20 ng/mL, Gleason score of 4 or higher, or personal preference of the referring urologist. The median follow-up was five years.
The five-year year actuarial bRFS rate was 56% and the clinical relapse-free survival rate was 86%, according to a report in European Urology (published online ahead of print). The presence of perineural invasion at RP and an increasing pre-SRT PSA level were independent predictors of decreased bRFS. The addition of ADT appeared to improve bRFS. On multivariate analysis, none of the variables predicted clinical relapse-free survival. The five-year risk of grade 2-3 toxicity was 22% for genitourinary symptoms and 8% for gastrointestinal symptoms.
In their discussion of study limitations, the researchers noted that their study lacked a low-dose control group and “differences in patient characteristics and surgical protocols might be a possible explanation for the observed differences.”