Dietary Beta Carotene May Decrease Risk of Prostate Cancer Among Smokers, UB Study Shows

BOSTON -- A new study by University at Buffalo epidemiologists suggests that beta carotene, or a dietary component associated with it, may reduce a smokerÍs risk of developing prostate cancer.

Researchers found no reduction in risk with beta carotene among men who had never smoked.

Results of the study were presented here today (Saturday, June 15) at the annual meeting of the Society for Epidemiologic Research.

The study was based on the premise that beta carotene may protect against the carcinogenic effect of tobacco smoke, said Hsien-Hsien Huang, doctoral candidate in the UB Department of Social and Preventive Medicine and lead author on the study.

Her investigation involved 415 men between the ages of 41 and 85 years with prostate cancer and 524 men without cancer selected from Erie and Niagara counties in western New York State. The men completed questionnaires that included information on smoking history and the foods they usually ate.

The researchers grouped participants according to a low, medium or high beta-carotene intake, and also grouped them by smoking status into never smokers, light smokers and heavy smokers. Researchers then assessed the relationship between various levels of beta-carotene intake, smoking levels and risk of prostate cancer.

Results showed that light smokers were two-thirds less likely to get prostate cancer if they ate medium to high levels of beta carotene, compared to light smokers who consumed low amounts of beta carotene in their diets.

Heavy smokers received a reduction in risk from dietary beta carotene only when they consumed high levels in their diet. At high levels, their risk of prostate cancer was reduced by about 50 percent, compared to heavy smokers who had low levels of beta carotene in their diets.

Among men who had never smoked, beta carotene intake had no effect on their prostate cancer risk.

"The research on the relationship between either smoking or dietary beta carotene and prostate cancer has been inconsistent," Huang said. "Failure to look at this interaction may explain some of the inconsistencies, but further studies are needed to confirm it."

Huang emphasized that the study investigated dietary beta carotene, not beta-carotene supplements, raising the possibility that other dietary factors also may be involved. There is clear evidence, however, of a link between smoking and several types of cancer, she noted, a risk that can be reduced by stopping smoking.

Also contributing to the study were Saxon Graham, James R. Marshall, John E. Vena, Maria Zielezny, John Brasure, Rosemary Laughlin and Jo L. Freudenheim of the UB Department of Social and Preventive Medicine.