Radiotherapy after radical prostatectomy: does transient androgen suppression improve outcomes?

PURPOSE

The long-term biochemical relapse-free survival and overall survival were compared for patients receiving either radiotherapy (RT) alone or radiotherapy combined with a short-course of total androgen suppression for failure after radical prostatectomy.

METHODS AND MATERIALS

Between 1985 and 2001, a total of 122 patients received RT after radical prostatectomy at our institution. Fifty-three of these patients received a short-course of total androgen suppression (TAS) 2 months before and 2 months concurrent with RT with a nonsteroidal antiandrogen and an luteinizing hormone-releasing hormone (LHRH) agonist (combined therapy group); the remaining 69 patients received RT alone. Treatment failure was defined after postoperative RT as a detectable PSA >0.05 ng/mL. Clinical and treatment variables examined included: presurgical PSA, clinical T stage, pathologic Gleason sum (pGS), seminal vesicle (SV) involvement, lymph node involvement, surgical margins, pre-RT PSA, prostate dose, pelvic irradiation, indication for postoperative RT (salvage or adjuvant), and time interval between surgery and RT. Minimum follow-up after postoperative RT was 1 year and median follow-up was 5.9 years (maximum, 14 years) for patients receiving RT alone, and 3.9 years (maximum, 11 years) for patients receiving RT with TAS (combined therapy group). Kaplan-Meier analysis was performed for PSA failure-free survival (bNED) and for overall survival (OS). Cox proportional hazards multivariable analysis examined the influence all clinical and treatment variables predicting for bNED and OS.

RESULTS

The median time to PSA failure after postoperative RT was 1.34 years for the combined therapy group and 0.97 years for the RT alone group (p = 0.19), with no failures beyond 5 years. At 5 years, the actuarial bNED rates were 57% for the combined therapy group compared with 31% for the RT alone group (p = 0.0012). Overall survival rates at 5 years were 100% for the combined therapy group compared with 87% for the RT alone group (p = 0.0008). For pGS <or=7, the 5-year bNED rates were 58% for combined therapy and 38% for RT alone (p = 0.0155), and for pGS >or=8 the 5-year bNED rates were 65% for combined therapy and 17% for RT alone (p = 0.075). The 5-year OS rates for pGS <or=7 were 100% for combined therapy and 98% for RT alone group (p = 0.106), and the 5-year OS for pGS >or=8 was 100% for combined therapy and 54% for RT alone (p = 0.04). On multivariable analysis, only SV involvement (p = 0.0145) and the addition of short-course TAS to postoperative RT (p = 0.0019) were significant covariates predicting for bNED and, similarly, approached significance for overall survival (p = 0.0594 and p = 0.0856, respectively).

CONCLUSIONS

Radiotherapy combined with a short-course TAS after radical prostatectomy appears to confer a PSA relapse-free survival advantage and possibly an overall survival advantage when compared with RT alone. The hypothesis that a transient course of androgen suppression with salvage or adjuvant RT after prostatectomy improves outcomes will need to be tested in a randomized trial.