Body Mass Index and Weight Change in Men with Prostate Cancer: Progression and Mortality

INTRODUCTION: Body Mass Index (BMI) is a modifiable life style factor that has been associated with an increased risk of fatal prostate cancer and biochemical recurrence. The main purpose of the present study was to investigate the association between the exposure BMI at the time of a prostate cancer diagnosis and weight change after diagnosis, and the outcomes of prostate cancer progression and mortality in a large cohort study.

METHODS: Data from 4376 men diagnosed with clinically localized prostate cancer between 1997 and 2002 were analyzed. BMI and weight change were self-reported in 2007. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.

RESULTS: Progression was experienced among 639 (14.6%) of the study participants, and in total 450 (10.3%) deaths of any cause and 134 (3.1%) prostate cancer specific deaths were recorded during follow-up. Obese men had a 41% increased rate of overall mortality compared to normal weight men (HR: 1.41, 95% CI: 1.02-1.94). A weight loss of greater than 5% after diagnosis doubled the rate of overall mortality compared to maintaining a stable weight (HR: 2.01, 95% CI: 1.50-2.69), while a weight gain greater than 5% was associated with an almost 60% increased rate of prostate cancer specific mortality (HR: 1.59, 95% CI: 1.00-2.53).

CONCLUSIONS: Being obese was associated with an increased rate of overall mortality and gaining weight after a prostate cancer diagnosis was associated with an increased rate of prostate cancer specific mortality.