Men who consume high quantities of fruits, especially citrus fruits and juices, have a significantly lower risk of developing oral premalignant lesions, irregular tissue that has not yet developed into cancer, according to the findings published in the American Journal of Epidemiology.

"Virtually all oral squamous cell carcinomas arise from a premalignant precursor," Dr. Kaumudi Joshipura, of Harvard School of Public Health, Boston, and colleagues write. "Epidemiologic studies have found that 16 to 40 percent of oral premalignant lesions transform to cancer," they note.

Squamous cell carcinoma is the second most common form of skin cancer, and is primarily composed of epidermis, the cells that make up the outer layer of the skin. Squamous cell carcinoma is not serious if identified early and promptly treated. However, once advanced, it is harder to treat and a small percentage can spread to other parts of the body.

The researchers examined fruit and vegetable consumption and the rate of oral premalignant lesions among 42,311 U.S. men enrolled in the Health Professionals Follow-up Study. Food frequency questionnaires were used to assess diet every 4 years.

A total of 207 cases of oral premalignant lesions occurred between 1986 and 2002.

Citrus fruits, citrus fruit juice, and vitamin C-rich fruits and vegetables were associated with a significantly lower risk of oral premalignant lesions. Greater quantities of these foods in the diet were linked to a 30- to 40-percent lower risk.

For example, the risk of oral premalignant lesions in subjects with the highest level of citrus fruit juice in the diet was 30 percent lower than those with the lowest level.

Overall, the researchers conclude that "dietary recommendations to increase consumption of fruits are appropriate for preventing oral precancer and cancer."

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