Serum Prostate-Specific Antigen Hemodilution Among Obese Men Undergoing Screening in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial
- Robert L. Grubb III1,
- Amanda Black3,4,
- Grant Izmirlian2,
- Thomas P. Hickey5,
- Paul F. Pinsky3,
- Jerome E. Mabie5,
- Thomas L. Riley5,
- Lawrence R. Ragard6,
- Philip C. Prorok2,
- Christine D. Berg3,
- E. David Crawford7,
- Timothy R. Church8,
- Gerald L. Andriole, Jr.1 and
- for the PLCO Project Team
- 1Division of Urologic Surgery, Washington University School of Medicine, St. Louis, Missouri; 2Biometry Research Group and 3Early Detection Research Group 4Division of Cancer Prevention, and Cancer Prevention Fellowship Program, Office of Preventive Oncology National Cancer Institute, NIH, Bethesda, Maryland; 5Information Management Services and 6Westat, Inc., Rockville, Maryland; 7University of Colorado Health Sciences Center, Denver, Colorado; and 8University of Minnesota, Minneapolis, Minnesota
- Requests for reprints:
Gerald L. Andriole, Jr., Division of Urologic Surgery, Washington University School of Medicine, 4960 Children's Place, Campus Box 8242, St. Louis, MO 63110. Phone: 314-362-8212; Fax: 314-361-2203. E-mail: andrioleg{at}wudosis.wustl.edu
Abstract
Background: Previous studies have shown an inverse relationship between prostate-specific antigen (PSA) concentration and body mass index (BMI). It has been recently proposed that this relationship may be explained by the larger plasma volume of obese men diluting a fixed amount of PSA (hemodilution effect). We examined this hypothesis in a cohort of men enrolled in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.
Methods: Of 38,349 men ages 55 to 74 years randomized in PLCO to receive annual PSA and digital rectal examination screening, 28,380 had a baseline PSA, complete demographic information, and no prostate cancer diagnosis within 6 years from baseline. Self-reported height and weight were used to calculate BMI and to estimate plasma volume. PSA mass was estimated as PSA concentration times plasma volume. Multivariable linear regression models were used to investigate the relationship between PSA concentration, plasma volume, PSA mass, and BMI.
Results: PSA concentration significantly decreased with increasing BMI (P < 0.001); mean PSA values were 1.27, 1.25, 1.18, and 1.07 ng/mL among normal (BMI, 18.5-25), overweight (BMI, 25-30), obese (BMI, 30-35), and morbidly obese (BMI, >35) men, respectively. However, plasma volume also increased with increasing BMI and PSA mass showed no association with BMI, with mean values of 3.78, 3.95, 3.97, and 3.82 μg across the four BMI categories (P = 0.10).
Conclusions: This study confirms earlier findings that the inverse relationship between PSA concentration and BMI may be explained by a hemodilution effect. These findings could have implications for prostate cancer screening in large men. (Cancer Epidemiol Biomarkers Prev 2009;18(3):748–51)
Footnotes
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- Accepted December 11, 2008.
- Received October 6, 2008.
- Revision received November 20, 2008.
