CHAPEL HILL, N.C. — Prostate cancer is one of the great mysteries in the medical community.

The two big questions: Why are African American men twice as likely to die from it than white men. And why is North Carolina near the top of the list for prostate cancer deaths?

Local researchers hope to answer those questions.

North Carolina ranks seventh in the nation for prostate cancer deaths. An estimated 930 men died of the disease in 2004. African-American men in the state have the highest incidence and death rate in the world.

Louisiana is on the lower end of the scale, with just 480 deaths this year.

Why the disparities? One reason may be diet.

"In North Carolina, we see more of a pork-based diet, versus the diet in Louisiana, which is more shellfish-based," said Dr. Jeannette Bensen, co-director of the

Prostate Cancer Project

.

The UNC researcher said it is not known what effect those foods play in prostate cancer. A three-year study will seek answers from newly-diagnosed prostate cancer patients in North Carolina and Louisiana.

Researchers will ask those men about their lifestyles, their access to health care and whether they received recommended prostate screenings.

"In doing this, we also feel we can demonstrate where public health resources should be focused to reduce the number of prostate cancer deaths," Bensen said.

The

American Cancer Society

recommends prostate cancer screening starting at age 50. Exams should begin at age 40 for African-American men or those with a family history of the disease.

The screening should consist of a PSA blood test and a digital exam.