(IN)-efficacy of salvage radiotherapy for rising PSA or clinically isolated local recurrence after radical prostatectomy

Abstract 

To determine the efficacy of external beam radiotherapy (RT) as salvage treatment for prostate-specific antigen (PSA) failure or local recurrence after radical prostatectomy.

Between 1991 and 1997, 98 patients underwent salvage RT to the prostatic bed at the Toronto Sunnybrook Regional Cancer Centre for PSA failure or local recurrence after radical prostatectomy. Thirty-six patients were treated for persistently detectable postoperative PSA levels (Group A), 26 for a delayed PSA rise (Group B), and 36 for palpable and/or biopsy-proven local recurrence (Group C). None had clinically apparent distant metastasis at the time of salvage RT. Freedom from PSA failure was defined as the maintenance of PSA ≤0.2 ng/mL. Cox regression analyses were performed to identify factors predictive of relapse.

The median follow-up from radical prostatectomy and RT was 5.11 and 4.21 years for Group A, 5.31 and 3.32 years for Group B, and 7.85 and 3.95 years for Group C, respectively. The initial PSA response rate was encouraging at a range of 86—94%. The complete PSA response rate (PSA ≤0.2 ng/mL) was lower, however and ranged from 53% to 62%. The actuarial relapse-free rate, including freedom from PSA failure, at 4 years was 26%, 39%, and 14% for Groups A, B, and C, respectively. At the time of the last follow-up, 49, 20, and 1 patient had PSA failure alone, distant metastasis, and local progression, respectively. The actuarial survival rate at 4 years was 89%, 95%, and 94% for Groups A, B, and C, respectively. On Cox regression analysis, the significant predictors for relapse were PSA level before salvage RT and Gleason score for Group A, none for Group B, and margin status for Group C.

The efficacy of salvage RT for PSA failure or local recurrence after RT was limited, reflected by very low relapse-free rates. Salvage RT appeared more efficacious for patients with a delayed PSA rise than for those with either persistently detectable postoperative PSA levels or clinically palpable local recurrence. Other strategies such as a combination of salvage RT and hormonal therapy need to be explored.

Keywords:  Salvage radiotherapy, Failure after surgery, Prostate cancer