Obese men are more likely to die of prostate cancer and more likely to be diagnosed with late-stage prostate cancer, according to some studies. Researchers in Texas looked at whether being overweight or obese lowers a man's level of prostate-specific antigen, or PSA, which is often used to screen for and diagnose prostate cancer.

What the researchers wanted to know: How does being overweight or obese affect levels of prostate-specific antigen?

What they did: The researchers used data from a study on detecting prostate cancer that's being carried out with men in and around San Antonio. Eventually, the study is supposed to help find risk factors and new ways to detect prostate cancer. The men in the study are healthy and haven't had prostate cancer.

What they found: Healthy overweight and obese men had lower PSA levels than normal-weight men. (And obese men had lower levels than men who were just overweight.)

What the study means to you: This suggests that a normal-seeming PSA level in a heavy man could actually indicate that he has abnormal prostate growth. That could explain why such men's prostate cancer is often detected at a more advanced stage.

Caveats: The researchers don't know why being overweight would lower PSA levels, but they speculate that overweight men's higher estrogen and lower testosterone levels could affect the production of PSA.

Find out more: A little basic information on the PSA test from the National Library of Medicine

Read the article: Baillargeon, J., et al. "The Association of Body-Mass Index and Prostate-Specific Antigen in a Population-Based Study." Cancer. Published online Jan. 24, 2005.