Risk-adapted androgen deprivation and escalated three-dimensional conformal radiotherapy for prostate cancer: Does radiation dose influence outcome of patients treated with adjuvant androgen deprivation? A GICOR study.

PURPOSE: Multicenter study conducted to determine the impact on biochemical control and survival of risk-adapted androgen deprivation (AD) combined with high-dose three-dimensional conformal radiotherapy (3DCRT) for prostate cancer. Results of biochemical control are reported. PATIENTS AND METHODS: Between October 1999 and October 2001, 416 eligible patients with prostate cancer were assigned to one of three treatment groups according to their risk factors: 181 low-risk patients were treated with 3DCRT alone; 75 intermediate-risk patients were allocated to receive neoadjuvant AD (NAD) 4-6 months before and during 3DCRT; and 160 high-risk patients received NAD and adjuvant AD (AAD) 2 years after 3DCRT. Stratification was performed for treatment/risk group and total radiation dose. RESULTS: After a median follow-up of 36 months (range, 18 to 63 months), the actuarial biochemical disease-free survival (bDFS) at 5 years for all patients was 74%. The corresponding figures for low-risk, intermediate-risk, and high-risk disease were 80%, 73%, and 79%, respectively (P = .847). Univariate analysis showed that higher radiation dose was the only significant factor associated with bDFS for all patients (P = .0004). When stratified for treatment group, this benefit was evident for low-risk patients (P = .009) and, more interestingly, for high-risk patients treated with AAD. The 5-year bDFS for high-risk patients treated with AAD was 63% for radiation doses less than 72 Gy and 84% for those > or = 72 Gy (P = .003). CONCLUSION: The results of combined AAD plus high-dose 3DCRT are encouraging. To our knowledge, this is the first study showing an additional benefit of high-dose 3DCRT when combined with long-term AD for unfavorable disease.