Body mass index, PSA, and prostate cancer risk

Abstract

5159 Objectives: Body size, assessed by body mass index (BMI), is consistently associated with numerous cancers. However, the relationship between BMI and risk of prostate cancer is not clear. Recent studies have noted an inverse association between BMI and prostate specific antigen (PSA), as well as BMI and prostate cancer incidence, though a direct association between BMI and prostate cancer mortality. These analyses investigate the association between BMI and PSA and prostate cancer incidence, in a population of older veterans enrolled in a case-control study of diet and prostate cancer risk. Methods: Cases and biopsy negative controls were recruited upon referral for prostate biopsy and frequency age-matched; PSA normal controls were identified from VA primary care clinic. BMI was determined from recorded height and weight. Detailed data was obtained regarding risk factors for prostate cancer and dietary intake. BMI was treated as a categorical variable (<25, 25 <30, 30<35, >35). Results: Subjects included 142 incident prostate cancer cases, 249 biopsy negative controls and 232 PSA normal clinic controls. In general linear models, adjusted for age, diabetes, use of non-steroidal anti- inflammatories, family history of prostate cancer, total caloric intake, fat intake, cholesterol intake and race, men with higher BMI had significantly lower PSA values (p=0.008 all subjects, p=0.001 biopsy subjects). Among men having undergone biopsy, BMI was associated with significantly lower PSA density (PSA/ prostate volume; p=0.0008). In logistic regression models adjusted for age, family history of prostate cancer and race, higher BMI was significantly inversely associated with risk of any prostate cancer (OR= for highest vs. lowest BMI category =0.40 (95% CI =0.19–0.87)), and specifically risk of high grade (Gleason ≥7) prostate cancer (OR= for highest vs. lowest BMI category =0.20 (95% CI =0.06–0.64)). Conclusions: Our results suggest that body size, as determined by BMI is inversely associated with PSA and risk of prostate cancer. However, BMI is an imprecise measure of visceral adiposity, perhaps the most important type of adiposity in relation to cancer risk. Our results support those of others and indicate that BMI may reduce risk of prostate cancer among this group of older veterans. No significant financial relationships to disclose.