Obesity May Influence Interpretation of Prostate Cancer Screening Results
According to a study published in the journal Cancer, levels of prostate-specific antigen (PSA) are lower in obese men than in normal weight men. The PSA level that arouses a suspicion of prostate cancer may therefore be lower in obese men.
The prostate is a gland of the male reproductive system. It produces some of the fluid that transports sperm during ejaculation. One in six men in the U.S. will develop prostate cancer during his lifetime. Prostate cancer occurs more frequently in older men, in African-American men, and in men with a family history of prostate cancer.
Men 50 years of age or older in the U.S. are often offered prostate-specific antigen (PSA) testing for the early detection of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate.
To explore how body size affects PSA levels, researchers evaluated information from the Southern Community Cohort Study. This study enrolled individuals between the ages of 40 and 79 years who resided in the southeastern United States. Information was available for 149 white men and 150 African American men.
Body size was measured using the body mass index (BMI). BMI is a comparison of weight to height (kg/m2). A BMI between 25 and 29 is generally considered overweight, and a BMI of 30 or higher is considered obese.
- Among men under the age of 60, there was a significant decline in PSA level as BMI increased. Average PSA levels were 0.81 ng/mL among men with a BMI less than 25 and 0.59 ng/mL among men with a BMI of 35 or higher.
- The decline in PSA with increasing BMI was observed among both African American and white men.
The researchers conclude that BMI influences PSA levels. The researchers note “…our findings suggest that clinical suspicion might be heightened with a marginally elevated PSA level in an obese person.”
Reference: Fowke JH, Signorello LB, Chang SS et al. Effects of Obesity and Height on Prostate-specific Antigen (PSA) and Percentage of Free PSA Levels among African-American and Caucasian Men. Cancer. Early online publication October 9, 2006.
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