Purpose: We compared the long-term results of postprostatectomy radiotherapy (RT) from two institutions, one adapting a prospective policy of adjuvant RT and the other salvage RT.
Methods and materials: Between 1989 and 1997, 69 patients were referred for adjuvant RT to the institution using adjuvant RT and 88 patients with evidence of recurrence were treated in the institution using salvage RT. The salvage group underwent RT after longer postoperative intervals (median, 40.3 vs. 2.9 months; p <0.0001) and had higher prostate-specific antigen (PSA) values before starting RT (4.5 vs. 0.86 ng/mL; p = 0.003). Both groups were routinely treated to a minimal total dose of 60 Gy. The treatment groups were analyzed for overall survival, disease-specific survival, distant metastasis-free survival, and biochemical recurrence-free survival (BRFS) using Cox proportional hazards modeling.
Results: Of the 69 patients referred for adjuvant RT, 22 (32%) had nonzero PSA values before RT. Multivariable modeling of BRFS found only the PSA value before RT to be statistically significant (p <0.0001). RT after prostatectomy was equally effective in either setting when the pre-RT PSA level was <1 ng/mL. When the PSA value before RT was >or=1 ng/mL, the 5-year BRFS for each group was inferior.
Conclusion: Although the adjuvant treatment policy was associated with significantly improved BRFS, this was attributable to low pre-RT PSA values. When the treatment groups were stratified for pre-RT PSA level, the differences in BRFS were not statistically significant. Patients with a rising PSA level after prostatectomy, regardless of their initial risk, should receive prompt referral for RT.