Effect of whole pelvic radiotherapy for patients with locally advanced prostate cancer treated with radiotherapy and long-term androgen deprivation therapy

Purpose: To evaluate the effect of whole pelvic radiotherapy (WPRT) in prostate cancer patients treated with RT and long-term (>1 year) androgen deprivation therapy (ADT). Methods and materials: Prostate cancer patients with high-risk features (Stage T3-T4 and/or Gleason score ≥7 and/or prostate-specific antigen level ≥20 ng/mL) who had undergone RT and long-term ADT were included in the present analysis. Patients with bowel inflammatory disease, colon diverticula, and colon diverticulitis were excluded from WPRT and treated with prostate-only radiotherapy (PORT). Patients were grouped according to nodal risk involvement as assessed by the Roach formula using different cutoff levels (15%, 20%, 25%, and 30%). Biochemical disease-free survival (bDFS) was analyzed in each group according to the RT type (WPRT or PORT). Results: A total of 358 patients treated between 1994 and 2007 were included in the analysis (46.9% with WPRT and 53.1% with PORT). The median duration of ADT was 24 months (range, 12-38). With a median follow-up of 52 months (range, 20-150), the overall 4-year bDFS rate was 90.5%. The 4-year bDFS rate was similar between the patients who had undergone WPRT or PORT (90.4% vs. 90.5%; p = NS). However, in the group of patients with the greatest nodal risk (>30%), a significant bDFS improvement was recorded for the patients who had undergone WPRT (p =.03). No differences were seen in acute toxicity among the patients treated with WPRT or PORT. The late gastrointestinal toxicity was similar in patients treated with PORT or WPRT (p = NS). Conclusions: Our analysis has supported the use of WPRT in association with long-term ADT for patients with high-risk nodal involvement (>30%), although a definitive recommendation should be confirmed by a randomized trial.