Benefit on biochemical control of adjuvant radiation therapy in patients with pathologically involved seminal vesicles after radical prostatectomy

Aims and background: To determine whether there is a benefit for biochemical control with adjuvant radiation therapy to the surgical bed following radical prostatectomy in patients with seminal vesicle invasion and pathologically negative pelvic lymph nodes (pT3b-pT4 pN0). Methods: We retrospectively reviewed the clinical records of radical prostatectomy patients treated between 1995 and 2002. A total of 66 patients with seminal vesicle invasion were identified: 45 of these patients received adjuvant radiation therapy and 21 were observed. Radiation therapy was initiated within 4 months of prostatectomy. Median dose was 66 Gy (range, 60-70 Gy). Median follow-up from the day of surgery was 40.6 months (mean, 41.5; range, 12-99). Biochemical recurrence was defined as the first value ≥0.2 ng/ml. Results: At two years, the proportion of patients free from biochemical recurrence was 80% in patients who received adjuvant radiation therapy versus 54% for those not given radiation therapy (P = 0.036). Actuarial biochemical recurrence at 5 years was 59% vs 41% for the radiation therapy and no radiation therapy groups, respectively. On univariate Cox regression model, the hazard of biochemical failure was also associated with a detectable (≥0.2 ng/ml) postsurgical prostate-specific antigen (P = 0.02) prior to radiation therapy. Pathological T stage (pT3b vs pT4), Gleason score, primary Gleason pattern and positive surgical margins were not significantly associated with biochemical recurrence. The hazard of biochemical failure was around 85% lower in the radiation therapy group than in the observation group (P = 0.002). Conclusions: Data from the present series suggest that adjuvant radiation therapy for patients with seminal vesicle invasion and undetectable (≤0.2 ng/ml) postoperative prostate-specific antigen significantly reduces the likelihood of biochemical failure.