14546 Background: We report a single-institution analysis of the role of androgen ablation (AA) with low-dose rate brachytherapy. Methods: A cohort of 189 consecutive patients (AA: n = 68, no-AA: n = 121) receiving brachytherapy (iodine-125: n = 125; palladium-109: n = 64) at our institution who had demographic (age), disease (T-stage [T1–70%, T2–28%, T3–2%], Gleason Score [median score 6], PSA [median-7.7 ng/mL]), and treatment (isotope, dosimetric endpoints, use of supplemental external beam radiotherapy [EBRT, administered as 45 Gy/1.8 Gy to the pelvis using 4-field technique with isocentric prescription]) information available, and a minimum of 2 years of follow-up available, constitute the analysis study group (median follow-up - 4.0 years). This cohort was divided into 2 major groups based on the use of AA (leuprolide 22.5 mg IM injection(s) 3–6 months [mean 4.0 months] prior to brachytherapy). Using 2 successive PSA rises > 1 ng/mL as the failure definition, biochemical failure-free survival (BFFS) curves were constructed and compared using the logrank test; additionally, multivariate analysis of all major patient and treatment factors was performed using the Cox proportional hazards model. These analyses were done for the whole cohort as well as for subgroups defined by the use of EBRT and for subgroups of patients with low-, intermediate-, and high-risk prognostic factors (defined as the basis of 0, 1, or ≥ 2 prognostic factors [PSA > 10 ng/mL, Gleason score > 6, T-stage > T2a], repectively). Results: The 4-year BFFS in the AA vs no-AA groups was 76 vs 70% (p = 0.230) for the whole cohort, 75 vs 62% (p = 0.182) for EBRT patients, and 75 vs 82% (p = 0.764) for no-EBRT patients. For the whole cohort, the use of EBRT was the only factor reaching significance on multivariate analysis (p = 0.040). When analyzing the EBRT and no-EBRT subgroups separately, no factor, including AA, reached significance on multivariate analysis. 4Y-BFFS of the AA vs no-AA subgroups were 82 vs 76% (p = 0.236) for the low-risk, 76 vs 70% (p = 0.437) for the intermediate-risk, and 75 vs 70% (p = 0.185) for the high-risk subgroup. Conclusions: In our study, short-course AA conferred no significant biochemical control advantage when added to low-dose rate brachytherapy overall or for any subgroup based on prognostic risk. No significant financial relationships to disclose.
Radiation Risk from Chronic Low Dose-Rate Radiation Exposures: The Role of Life-Time Animal Studies - Workshop October 2005