Obesity is associated with castration-resistant disease and metastasis in men treated with androgen deprivation therapy after radical prostatectomy: results from the SEARCH database

OBJECTIVE To investigate whether obesity predicts poor outcomes in men starting androgen deprivation therapy (ADT) before metastasis, since previous studies found worse outcomes after surgery and radiation for obese men. METHODS A retrospective review was carried out of 287 men in the SEARCH database treated with radical prostatectomy between 1988 and 2009. Body mass index (BMI) was categorized to <25, 25-29.9 and >= 30 kg/m2. Proportional hazards models were used to test the association between BMI and time to castration-resistant prostate cancer (PC), metastases and PC-specific mortality adjusting for demographic and clinicopathological data. RESULTS During a median 73-month follow-up after radical prostatectomy, 403 men (14%) received early ADT. Among 287 men with complete data, median BMI was 28.3 kg/m2. Median follow-up from the start of ADT was 52 months during which 44 men developed castration-resistant PC, 34 developed metastases and 24 died from PC. In multivariate analysis, higher BMI was associated with a trend for greater risk of progression to castration-resistant PC (P = 0.063), a more than threefold increased risk of developing metastases (P = 0.027) and a trend toward worse PC-specific mortality (P = 0.119). Prognostic biomarkers did not differ between BMI groups. CONCLUSIONS Among men treated with early ADT, our results suggest that obese men may have increased risk of PC progression. These data support the general hypothesis that obesity is associated with aggressive PC, although validation of these findings and further study of the mechanisms linking obesity and poor PC outcomes are required.