title: Obesity as a predictor of biochemical recurrence and survival after radiation therapy for prostate cancer.
abstract: OBJECTIVE
  Obesity has been demonstrated to predict biochemical progression in men undergoing radical prostatectomy for prostate adenocarcinoma, and is associated with a higher risk of biochemical and clinical relapse after radiation therapy (RT). We evaluated if obesity, determined by body mass index (BMI), is associated with adverse disease characteristics, pre-treatment serum testosterone, biochemical disease free survival (bDFS), disease-specific survival (DSS), or overall survival (OS) in patients undergoing radical external beam radiation therapy for prostate cancer.
  
  
  METHODS
  A cohort of 706 patients with localized prostate adenocarcinoma treated with RT between 1993 and 2001 were categorized as obese (BMI > or = 30 kg/m(2)), overweight (BMI 25-29.9 kg/m(2)) or normal (BMI < 25 kg/m(2)). The association between BMI, disease characteristics, and progression were evaluated by Chi-square and ANOVA tests, Kaplan-Meier survival analysis, and Cox regression analysis.
  
  
  RESULTS
  195 patients (27.6%) were normal weight, 358 (50.7%) were overweight and 153 (21.7%) were obese. Obese men had lower serum testosterone levels than overweight and normal-weight men (means 12.8, 14.1, and 15.7 nmol/L, respectively; p < 0.001). The BMI groups did not differ in Gleason score, pretreatment PSA, or stage. On multivariate analysis, BMI group was predictive of reduced bDFS (p = 0.02) and DSS (p = 0.008), with a trend toward reduced OS (p = 0.062).
  
  
  CONCLUSIONS
  Obesity was associated with lower serum testosterone levels but not with adverse pretreatment pathological features. Obese men have a higher risk of biochemical recurrence and prostate-cancer specific death after RT.
authors.affiliation: Radiation Oncology Program, British Columbia Cancer Agency, Vancouver, British Columbia, Canada. dpalma@bccancer.bc.ca
authors.forename: David
authors.initials: D
authors.lastname: Palma
authors.forename: Tom
authors.initials: T
authors.lastname: Pickles
authors.forename: Scott
authors.initials: S
authors.lastname: Tyldesley
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015992:Body Mass Index; D015331:Cohort Studies; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000401:mortality; D009367:Neoplasm Staging; D009765:Obesity / Q000150:complications*; D011468:Prostatectomy / Q000379:methods; D011471:Prostatic Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D012044:Regression Analysis; D016019:Survival Analysis; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone