Prognostic impact of abdominal adiposity, waist circumference and body mass index in patients with intermediate-risk prostate cancer treated with radiotherapy

Abstract

We tested the potential role of abdominal visceral (VAT) and subcutaneous (SAT) adipose tissues, waist circumference (WC) and body mass index (BMI) as prognostic factors in patients with intermediate-risk prostate cancer (clinical stage T1b-2b, and Gleason Score (GS)=7 and prostate-specific antigen PSA level <15 ng ml(-1), or GS ≤ 6 and PSA between 10 and 20 ng ml(-1)) treated with ultrasound-based image-guided radiotherapy. VAT, SAT and WC (measured from planning abdominal computed tomography) and BMI were compared with clinical and pathologic factors using univariate analyses. Cox regression analyses were performed to evaluate whether obesity indices significantly predicted biochemical disease free-survival (bDFS). Of the 112 eligible patients, 30 (27%) were obese. Median BMI at baseline was 27.5 kg m(-2) (range, 19.2-51.5 kg m(-2)). Greater abdominal adiposity, WC and BMI were significantly associated with younger age at diagnosis and increased prostate volume (P=0.003 and P=0.002, respectively). No significant correlation between obesity measures and T-stage, GS, PSA or percentage of positive cores at biopsy was found. On Cox regression analyses, none of the obesity measures predicted for bDFS. No association was observed between obesity indices and surrogate markers of biochemical failure as PSA nadir (nPSA) or time to nPSA. Abdominal adiposity, WC and BMI are associated with younger age at diagnosis and greater prostate volume but not with an increased risk of biochemical failure in patients with intermediate-risk prostate cancer.