Impact of body mass index on clinicopathologic outcome and biochemical recurrence after radical prostatectomy in 1,257 Japanese patients with prostate cancer.

176 Background: To determine the impact of body mass index (BMI) on the clinicopathological characteristics and biochemical recurrence of prostate cancer (PCa) after radical prostatectomy (RP) in Japanese men. Methods: The medical records of 1,257 men with PCa treated by radical prostatectomy without neoadjuvant therapy at four medical centers between 2001 and 2009 were retrospectively reviewed. Patients were categorized into four groups using the WHO BMI classification and recommended BMI quartiles. Associations of the various BMI categories with clinicopathological characteristics and biochemical recurrences were statistically evaluated. Biochemical recurrence was defined as a prostate specific antigen (PSA) level of >0.2 ng/ml. Results: Of the 1,257 patients, 230 (18.1%) experienced biochemical recurrence during the median follow-up period of 49 months. The median BMI was 23.8 kg/m2, and 1.4% patients were underweight, 65.4% were of normal weight, 30.9% were overweight, and 2.4% were obese (WHO classification). Preoperative PSA levels and PSA density (PSAD) were significantly higher in the underweight group than in the other groups. Pathological characteristics did not differ significantly among BMI categories. As per the WHO classification and quartile categories, biochemical recurrence rate was comparable among the BMI groups. After adjusting for other pre- and perioperative covariables, multivariate Cox proportional hazards analysis revealed that a high BMI did not have an independent impact on biochemical recurrence-free survival. Conclusions: Underweight Japanese PCa patients who underwent radical prostatectomy had higher preoperative PSA levels and PSAD. However, high BMI was not associated with increased biochemical recurrence rate.