The Efficacy and Sequencing of a Short Course of Androgen Suppression on Freedom From Biochemical Failure When Administered With Radiation Therapy for T2-T3 Prostate Cancer

Abstract

We evaluated the benefits and sequencing of androgen suppression (AS) administered with external beam radiation therapy (EBRT) in T2-T3 prostate cancers. Between 1990 and 1999, 481 patients were entered in 2 successive, prospective, randomized studies, including 161 in the study 1 and 325 in study 2. Eligible patients had clinical stages T2-T3 prostate cancer. In the first study (L-101) subjects were randomly allocated among EBRT alone (group 1), EBRT preceded by 3 months of AS (group 2), and neoadjuvant, concomitant and adjuvant AS for a total of 10 months (group 3). In the second study (L-200) we analyzed neoadjuvant and concomitant AS (total 5 months) vs neoadjuvant, concomitant and short course adjuvant (total 10 months) AS with EBRT. In each study we used a total AS (a luteinizing hormone-releasing hormone agonist plus an antiandrogen) and a standard dose of radiation therapy at that time. Patient characteristics were well balanced in regard to age, stage, prostate specific antigen and Gleason score. No biochemical evidence of disease (BNED) was defined as an end point according to the Vancouver rule. In the study 1 at a median followup of 5 years 7-year biochemical-free survival rates were 42%, 66% and 69% in groups 1 to 3, respectively. BNED was significantly different between groups 1 and 2 (p = 0.009) and between groups 1 and 3 (p = 0.003) but not between groups 2 and 3 (p = 0.6). Multivariate analysis using a Cox proportional hazards model showed an HR of 6.1 for Gleason score (p = 0.001), 1.4 for PSA (p = 0.002), 0.5 for group 1 vs group 2 (p = 0.01) and 0.35 for group 1 vs group 3 (p = 0.008). In study 2 BNED at 4 years was 65%. There was no significant difference between arms 1 and 2 (p = 0.55). The analysis of study 1 shows a benefit of using a short course of neoadjuvant AS with EBRT vs EBRT alone for localized T2-T3 prostate cancers. Moreover, in each study adding a short course of adjuvant AS after neoadjuvant 1 provided no more advantage in these patients.