Obesity Can Affect PSA Accuracy

Obesity is associated with lower prostate-specific antigen (PSA) levels in men, causing PSA tests to produce unreliable results, according to a new study appearing in the March 1, 2005, issue of Cancer.

Since 1990, when the use of PSA testing for early detection of prostate cancer became relatively common, the death rate has dropped. However, it is not certain if this drop is a direct result of screening. Recently, PSA screening has been found not to be as accurate as initially thought, and studies are under way to determine if early detection tests in large groups of men can lower the prostate cancer death rate.

Studies also show that obesity is associated with a poor prognosis. Hypotheses include tumorigenic links to elevated hormones such as estrogen and insulin-like growth factor. Another hypothesis is that obesity may actually make current screening tests insensitive.
This hypothesis was tested by Jacques Baillargeon, Ph.D., at the University of Texas Health Science Center (San Antonio, USA), and colleagues who investigated the association between body mass index (BMI) and PSA levels in 2,779 men without prostate cancer. The results showed that as BMI increased, PSA linearly decreased, regardless of age and race.

These findings may explain "the recent reports of inferior outcomes of prostate cancer treatment in obese men” in that they "may be caused by delayed detection” rather than biologic differences in the tumor, according to the study's authors. The study implies that
doctors may consider adjusting PSA levels when screening men who are overweight or obese.





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