Impact of obesity on biochemical control after radical prostatectomy for clinically localized prostate cancer: a report by the Shared Equal Access Regional Cancer Hospital database study group.

PURPOSE: Given the limited information regarding the impact of obesity on treatment outcomes for prostate cancer, we sought to examine the relationship between body mass index (BMI) and cancer control after radical prostatectomy (RP). PATIENTS AND METHODS: We compared clinicopathologic and biochemical outcome information across BMI groups from 1,106 men treated with RP between 1988 and 2002. Multivariate analysis was used to determine if BMI significantly predicted adverse pathology or biochemical recurrence.
RESULTS: Obesity was related to year of surgery (P <.001) and race (P <.001), with black men having the highest obesity rates. Obese patients had higher biopsy and pathologic grade tumors (P <.001). On multivariate analysis, BMI > or = 35 kg/m(2) was associated with a trend for higher rates of positive surgical margins (P =.008). Overweight patients (BMI, 25 to 30 kg/m(2)) had a significantly decreased risk of seminal vesicle invasion (P =.039). After controlling for all preoperative clinical variables including year of surgery, BMI > or = 35 kg/m(2) significantly predicted biochemical failure after RP (P =.002). After controlling for surgical margin status, BMI > or = 35 kg/m(2) remained a significant predictor of biochemical failure (P =.012). There was a trend for BMI > or = 35 kg/m(2) to be associated with higher failure rates than BMI between 30 and 35 kg/m(2) (P =.053).
CONCLUSION: The percentage of obese men undergoing RP in our data set doubled in the last 10 years. Obesity was associated with higher-grade tumors, a trend toward increased risk of positive surgical margins, and higher biochemical failure rates among men treated with RP. A BMI > or = 35 kg/m(2) was associated with a higher risk of failure than a BMI between 30 and 35 kg/m(2).