Obesity is not predictive of overall survival following permanent prostate brachytherapy

Purpose: To evaluate the impact of obesity on cause-specific (CSS), biochemical progression-free (bPFS), and overall survival (OS) following prostate brachytherapy. Materials and Methods: From April 1995 through March 2003, 1093 consecutive patients underwent brachytherapy for clinical T1b-T3a (2002 AJCC) prostate cancer. The median follow-up was 5.6 years. Evaluated body mass index (BMI) subgroups were <25 (n = 258), 25.0 to 29.9 (n = 547), 30.0 to 34.9 (n = 214), and >= 35 (n 74) kg/m(2), respectively. A total of 430 (39.9%) and 589 (53.9%) of the patients received androgen deprivation therapy or supplemental external beam radiation therapy, respectively. Multiple clinical, treatment, and dosimetric parameters were evaluated as predictors of CSS, bPFS, and OS. Results: The 11-year CSS, bPFS, and OS for the entire cohort were 97.5%, 95.6%, and 77.6%, respectively. BMI did not impact CSS or bPFS for any of the BMI cohorts. However, OS was statistically lower in patients with a BMI <25 kg/m(2) (p = 0.014). A Cox linear regression analysis demonstrated that Gleason score was the best predictor of CSS while percent-positive biopsies, risk group, V100 and hypertension predicted for bPFS. Patient age and tobacco use were the strongest predictors of OS. A total of 128 patients have died with 108 (84.4%) of the deaths the result of cardiovascular/pulmonary disease (73) and second malignancies (35). To date, 12 patients have died of metastatic prostate cancer. Conclusion: Obesity did not impact CSS, bPFS, or OS in patients treated with permanent prostate brachytherapy. Cardiovascular or pulmonary disease and second malignancies substantially outweighed prostate cancer as competing causes of death.