PSA Test Affected By Obesity, Hide Prostate Cancer

Extra pounds may affect PSA test, hiding prostate cancer

By Miranda Hitti
WebMD Medical News

Reviewed By Michael W. Smith, MD

Jan. 24, 2005 -- Obesity may hamper the accuracy of a common prostate cancer screening test.

A new study shows that obese men tend to have lower levels of prostate-specific antigen (PSA), which could make it harder to detect prostate cancer.

The finer points of the relationship between prostate cancer and obesity aren't 100% clear. But men needn't wait for all the details to shed excess pounds. From head to toe, it's far healthier to be in good shape.

Prostate Cancer, Obesity: Where We Stand

Prostate cancer is the most common type of cancer found in U.S. men apart from skin cancer, says the American Cancer Society (ACS). In 2005, there will be about 232,000 new cases of prostate cancer and some 30,350 prostate cancer deaths in America, predicts the ACS.

While prostate cancer's death rate is falling, it's still the second leading cause of cancer death among American men. "While 1 man in 6 will get prostate cancer during his lifetime, only 1 man in 33 will die of this disease," says the ACS. Prostate cancer is most common in older men.

It's no secret that obesity is also rampant in America. In 1999-2000, an estimated 64% of U.S. adults over age 20 were obese or overweight, says the CDC.

Obesity's Effects on Prostate Cancer

Recent studies suggest that obese men may be more likely to have advanced stages of prostate cancer with lower survival rates. Some research has also shown an increased prostate cancer risk for obese and overweight men, but other studies have contradicted that finding.

The link between obesity, excess weight, and prostate cancer got the attention of researchers including Jacques Baillargeon, PhD, of the University of Texas Health Center at San Antonio.

They examined PSA levels in obese and overweight men. Their study appears in the March 1 issue of the journal Cancer.

PSA is produced by the prostate gland. An increase in PSA or a high PSA level may indicate prostate cancer. But high PSA levels could also indicate prostate enlargement without cancer.

Higher Weight, Lower PSA

Almost 2,800 men participated in the study. None had prostate cancer. Overall, 81% were overweight or obese. That's based on their body mass index (BMI).

The men gave blood samples for a PSA test. The researchers found that PSA levels decreased with increasing body weight.

That's not necessarily cause for celebration. In this case, low PSA levels might not indicate health. Instead, it could mask prostate cancer, say the researchers.

They call for more studies to see if considering BMI with PSA improves early detection and survival for prostate cancer in obese and overweight men.

SOURCES: Baillargeon, J. Cancer, March 1, 2005; vol 103. WebMD Medical News: "Lose Weight, Lower Prostate Cancer Risk." American Cancer Society. CDC. WebMD Medical Reference from Healthwise: "Prostate-Specific Antigen (PSA) Test Overview." News release, John Wiley & Sons, Inc.

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