LOWER BODY MASS INDEX IS ASSOCIATED WITH A HIGHER PROSTATE CANCER DETECTION RATE AND LESS FAVORABLE PATHOLOGICAL FEATURES IN A BIOPSY POPULATION

Abstract

Body mass index (BMI), calculated as weight in kg divided by the square of height in m, is used as an indicator of obesity. We assessed the relationship between BMI, and prostate cancer detection rates and biopsy features in a referral based biopsy population. A total of 787 consecutive patients referred for abnormal digital rectal examination and/or prostate specific antigen (PSA) greater than 4 ng/ml underwent systematic prostate biopsy. Three standard categories of BMI were considered, namely normal-less than 25, overweight-25 to 29.9 and obese-30 or greater kg/m. The presence or absence of cancer, percent of core involvement and tumor grade were correlated with BMI. Additional analyses controlled for patient age, PSA and prostate volume. For the entire population detection rates were highest in the normal BMI group compared to the overweight or obese group (52% vs 37% vs 42%, p = 0.0026). When stratified by age, this observation was true for men younger than 70 years (49% vs 32% vs 37%, p = 0.0042) but not for men 70 years or older. When only patients with PSA 10 ng/ml or less were considered, detection rates were highest in the normal BMI group (44% vs 28% vs 36%, p = 0.0061). This observation also persisted in patients younger than 70 years with PSA 10 ng/ml or less, or when only patients younger than 70 years with a total prostate volume of less than 50 cc were included. Of patients with cancer those with a normal BMI had a greater length of needle core involvement on biopsy. Normal BMI correlates with a higher cancer detection rate and larger cancers in men undergoing prostate biopsy.