Predictors of improved outcome for patients with localized prostate cancer treated with neoadjuvant androgen ablation therapy and three-dimensional conformal radiotherapy.

Abstract

To identify prognostic variables that predict for improved biochemical and local control outcome in patients with localized prostatic cancer treated with neoadjuvant androgen deprivation (NAAD) and three-dimensional conformal radiotherapy (3D-CRT). Between 1989 and 1995, 213 patients with localized prostate cancer were treated with a 3-month course of NAAD that consisted of leuprolide acetate and flutamide before 3D-CRT. The purpose of NAAD in these patients was to reduce the preradiotherapy target volume so as to decrease the dose delivered to adjacent normal tissues and thereby minimize the risk of morbidity from high-dose radiotherapy. The median pretreatment prostate-specific antigen (PSA) level was 15.3 ng/mL (range, 1 to 560 ng/mL). The median 3D-CRT dose was 75.6 Gy (range, 64.8 to 81 Gy), and the median follow-up time was 3 years (range, 1 to 7 years). The significant predictors for improved outcome as identified in a multivariate analysis included pretreatment PSA level < or = 10.0 ng/mL(P < .00), NAAD-induced preradiotherapy PSA nadir < or = 0.5 ng/mL (P < .001), and clinical stage < or = T2c (P < .04). The 5-year PSA relapse-free survival rates were 93%, 60%, and 40% for patients with pretreatment PSA levels < or = 10 ng/mL, 10 to 20 ng/mL, and greater than 20 ng/mL, respectively (P < .001). Patients with preradiotherapy nadir levels < or = 0.5 ng/mL after 3 months of NAAD experienced a 5-year PSA relapse-free survival rate of 74%, as compared with 40% for patients with higher nadir levels (P < .001). The incidence of a positive biopsy among 34 patients pretreated with androgen ablation was 12%, as compared with 39% for 117 patients treated with 3D-CRT alone who underwent a biopsy (P < .001). For patients treated with NAAD and high-dose 3D-CRT, pretreatment PSA, preradiotherapy PSA nadir response, and clinical stage are important predictors of biochemical outcome. Patients with NAAD-induced PSA nadir levels greater than 0.5 ng/mL before radiotherapy are more likely to develop biochemical failure and may benefit from more aggressive therapies.