Prostate-specific antigen levels lower in obese men

Compared with normal weight men, overweight and obese men have lower prostate-specific antigen levels.

Researchers at Duke University in Durham, N.C. and other institutions examined data from 535 men enrolled in a prostate cancer-screening clinic to determine the link between BMI and digital rectal examination results and the relationship between weight at age 18 years and adult PSA or digital rectal examination findings.

Of those involved in the study, 391 (73%) were overweight or obese, 144 (27%) of whom were obese. Higher BMI was associated with lower PSA levels (P=.03), but not notably related to digital rectal examination results.

Adult PSA or digital rectal examination results were not significantly associated with weight at age 18 years.

The researchers proposed changing current PSA cut-points used to recommend biopsy to correlate to degree of obesity. – by Stacey L. Adams

Urology. 2008; doi:10.1016/j.urology.2007.11.036.

Obesity is emerging as being of major importance in the field of prostate cancer. We know obese men are more likely to have poorly differentiated tumors—tumors that grow faster and are more aggressive. We have also shown, in prior research, that men who are obese are more likely to have prostate cancer recurrence after they undergo radical prostatectomy treatment. Likewise, we know obesity increases the risk that men will present with more advanced prostate cancer and is associated with increased mortality in patients with prostate cancer.

In this article, the authors studied a prostate cancer screening population and clearly demonstrated a progressive reduction in PSA values associated with increasing BMI. This is an important finding and lends further evidence to the fact that we should adjust for the effect of obesity on PSA levels in men being screened for prostate cancer.

– William Aronson, MD

Professor, Department of Urology
University of California in Los Angeles

This study tells us that high BMIs (or obesity) can be a confounding variable in the use of PSA for prostate cancer screening. There has been a tremendous amount of research lately on the implications of obesity in prostate cancer, and this adds another important effect of obesity on the management of men with prostate cancer.

This information will not change practice, but will increase research in the future. There is not enough evidence to suggest that we should lower PSA cutoffs in obese men.

In terms of future research, these results need to be validated. This study involved only a small cohort of men in one center. We also need to establish more research regarding 1) ideal PSA cutoffs in obese men and 2) the amount by which we should lower PSA in certain men, i.e. what level of BMI requires what amount of PSA reduction?

– Alan So, MD

Assistant Professor
Department of Urologic Sciences, University of British Columbia