Objectives: To confirm an inverse relationship between obesity and serum prostate-specific antigen (PSA) levels in Japanese men with a smaller body mass index (BMI) than white and African-American men.
Methods: We analyzed 5246 apparently healthy Japanese men aged >20 years who visited our medical center for a health checkup from January 2004 to December 2006. The men were divided into 6 groups by age decade, and the BMI was categorized into 5 groups. The body fat percentage (BFP) was also used and was grouped into quartiles. The Mantel-Haenszel chi(2) test was used to check for trends in proportions of subjects with abnormal PSA values for each cutoff point (2.5 and 4.0 ng/mL) in these groups. The relationships between the PSA levels and BMI or BFP were examined using multivariate analysis.
Results: The median age, BMI, BFP, and PSA level was 46 years, 23.2 kg/m(2), 21.5%, and 0.78 ng/mL, respectively. The proportion of subjects with an abnormal PSA value increased significantly with age (P for trend < .0001); however, no trends were found across the BMI or BFP categories. The geometric mean PSA level increased significantly with age (P for linear trend < .0001) and decreased with BMI and BFP categories (P for linear trend = .001 and P for linear trend = .002, respectively).
Conclusions: Our findings have demonstrated an inverse relationship between obesity and PSA levels even in Japanese men with a low prevalence of obesity, such as was previously reported for American men. Therefore, in prostate cancer screening, obesity, which can affect the accuracy of PSA testing, independent of race and ethnicity, should be taken into account.