Low body mass index is associated with adverse oncological outcomes following radical prostatectomy in Korean prostate cancer patients

Purpose: The purpose of this study was to determine the impact of obesity on clinicopathological features and biochemical recurrence (BCR) following radical prostatectomy (RP) in Korean prostate cancer (PCa) patients. Methods: A single-institutional retrospective analysis was performed on 880 PCa patients treated by RP without neoadjuvant therapy between July 2005 and December 2011. Patients were stratified according to body mass index (BMI) standards for Asian populations: obese (BMI ≥25 kg/m²), overweight (BMI 23-24.9 kg/m²), or normal weight (BMI <23 kg/m²). For analysis, overweight and obese patients were combined (n = 592, BMI ≥23 kg/m²) and compared with normal weight patients (n = 288, BMI <23 kg/m²). BCR was defined as prostate-specific antigen (PSA) ≥0.2 ng/ml following RP. Results: Normal weight patients tended to be classified into the higher D'Amico risk category with smaller prostate volumes compared with obese and overweight patients. Normal weight patients had higher pathological Gleason scores and were at higher risk of BCR during the mean follow-up of 58.2 months. This translated to a higher 5-year BCR-free survival rate for obese and overweight patients compared with normal weight patients (77.8 vs. 70.3 %; p = 0.017). On multiple Cox-proportional hazards regression analysis incorporating variables of BMI category, PSA, positive surgical margins, pathological T stage, and Gleason score, higher BMI category remained a significant predictor of a lower risk of BCR (HR = 0.634, p = 0.028). Conclusions: Obese and overweight Korean PCa patients have lower Gleason scores and a reduced risk of BCR compared with normal weight patients. These findings suggest that body fat influences pathological features and oncologic outcomes of PCa.