Wallner, Lauren P.

Abstract Objective: To investigate the association of body mass index (BMI) and BMI change with change in prostate-specific antigen (PSA) level and to assess the possible roles of PSA hemodilution and prostate volume in explaining the obesity and PSA association. Methods: In 1990, a randomly selected cohort of Caucasian men, aged 40 to 79 years, from Olmsted County, Minnesota, completed questionnaires ascertaining demographic characteristics, current medical conditions, and medications biennially, with a subset undergoing blood draws and clinical examinations. Linear mixed models were used to predict annual changes and intercepts of individual changes in BMI, PSA, prostate volume, plasma volume, and PSA mass, adjusting for age in 545 men with at least 2 serial PSA, BMI, and prostate volume measurements. Results: Baseline BMI was inversely associated with the annual percent change in PSA, adjusting for age, baseline PSA, and prostate volume and for the rates of change in BMI and prostate volume (β = −0.003, 95% CI: −0.006 to −0.0003). Baseline obesity was positively associated with mean baseline levels and the rate of change in prostate volume (P = 0.002) and plasma volume (both P < 0.001) but was not associated with either the mean baseline values or the rate of change in PSA mass. Conclusions: Baseline obesity was associated with baseline PSA and prostate volume and with the rate of change in PSA over 15 years of follow-up. Impact: The inverse association of obesity with prostate cancer diagnosis may be at least partly due to detection bias, which is due to larger prostate volumes and PSA hemodilution in obese men. Cancer Epidemiol Biomarkers Prev; 20(3); 501–8. ©2011 AACR.

Abstract Prostate cancer is the second leading cause of cancer deaths among U.S. men. Early detection is associated with drastically improved 5-year survival rates. It is unclear, however, what psychosocial factors motivate or discourage men from taking advantage of both prostate-specific antigen (PSA) testing and digital rectal examination (DRE). The goal of the current study was to identify psychosocial factors that influence screening behavior for prostate cancer in a cohort of 2,447 men. In 1990, a randomly selected cohort of Caucasian men, ages 40 to 79 years, from Olmsted County, Minnesota, were enrolled in the study. These men completed a questionnaire containing queries on family history of prostate cancer, concern about getting prostate cancer, and marital status. Medical and laboratory records were reviewed to determine the number DREs (1989-1996) and PSA tests (1989-1998). Frequent screening was defined as the upper 25th percentile for number of DREs (>4) or PSAs (>3). Men who have a family history and men who worry or have concern about prostate cancer were more likely [odds ratio (OR), 1.5; 95% confidence interval (95% CI), 1.2-2.0 and OR, 1.9; 95% CI, 1.4-2.5] to seek screening compared with those without a family history or worry. The association between family history and frequent screening was similar in men who were married or living with someone (OR, 1.7; 95% CI, 1.2-2.2); however, it was reduced among men who live alone (OR, 0.6; 95% CI, 0.2-1.8). These data suggest that psychosocial factors such as family history, worry, or concern about prostate cancer and marital status may play an important role in men's decisions about prostate cancer screening. (Cancer Epidemiol Biomarkers Prev 2008;17(12):3588–92)