Body mass index and mortality in men treated for locally advanced prostate cancer: An analysis of RTOG 85–31
5128 Background: Greater body mass index (BMI) is associated with shorter time to prostate-specific antigen (PSA) failure following radical prostatectomy. We investigated whether BMI is associated with prostate cancer-specific mortality (PCSM) in a large randomized trial of men treated with radiation therapy (RT) and androgen deprivation therapy (ADT) for locally advanced prostate cancer. Methods: Between 1987 and 1992, 945 eligible men with locally advanced prostate cancer were enrolled on a phase III trial (RTOG 85- 31) and randomized to RT and immediate goserelin (Arm I) or RT alone followed by goserelin at relapse (Arm II). Height and weight data were available at baseline for 788 (83%) subjects. Cox regression analyses were performed to evaluate the relationships between BMI and all-cause mortality, PCSM, and non-prostate cancer mortality. Covariates included age, race, treatment arm, history of prostatectomy, nodal involvement, Gleason score, clinical stage, and BMI. Results: The 5-year PCSM rate for men with BMI<25kg/m2 was 6.5%, compared to 13.1% and 12.2% in men with BMI=25-<30 and BMI=30, respectively (Gray’s p=0.005). In multivariable analyses, as shown in the Table , greater BMI was significantly associated with higher PCSM [for BMI=25-<30, hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.02–2.27, p=0.04; for BMI=30, HR 1.65, 95% CI 1.02–2.66, p=0.04]. BMI was not associated with non-prostate cancer or all-cause mortality. Conclusions: Greater baseline BMI is independently associated with higher PCSM in men with locally advanced prostate cancer. Further studies are warranted to evaluate the mechanism(s) for increased mortality and to assess whether weight loss after prostate cancer diagnosis alters disease course. [Table: see text] No significant financial relationships to disclose.