Diet and salivary gland cancer

Cancer of the salivary glands is a rare disease, and little is known about its etiology. The only established risk factors for salivary gland cancer are radiation exposure and a history of cancer at other body sites. No previous studies of diet and salivary gland cancer in human subjects have been published.

This report describes a population-based case-control study of salivary gland cancer conducted in the San Francisco-Monterey Bay area, in which 141 cases and 191 control subjects were interviewed. Dietary data were collected using a food frequency questionnaire, and specific questions were asked about the use of nutritional supplements.

Vitamin C intake (including supplements) of [is greater than] 200 mg/day compared with [is less than or equal to] 100 mg/day was associated with a statistically significant 60% decrease in salivary gland cancer risk. Inverse associations were also observed for vitamin E, carotene, and fiber from fruits and vegetables, but these associations were diminished when adjusted for vitamin C intake. In men, the increase in risk of salivary gland cancer associated with tobacco use was greater among those with low vitamin C intake than among those with moderate to high intakes of this vitamin. Fiber from bean sources was associated with a 51% reduction in risk even after adjusting for vitamin C intake. Cholesterol intake was associated with an increase in risk.

The findings of this study suggest that dietary factors, especially vitamin C, some component of beans, and cholesterol, may influence the risk of salivary gland cancer. Preventive strategies developed for common chronic diseases, such as increased consumption of fruits and vegetables and limiting cholesterol intake, may also help to prevent this rare form of cancer. The apparent protective effect of vitamin C may be attributable to its antioxidant effect or to its ability to block the formation of nitrite, thus preventing the formation of carcinogenic nitrosamines. The saliva is one of the sites at which the conversion of nitrate to nitrite takes place. The protective effect of beans may be attributable to nonnutritive components such as phytoestrogens, which have also been associated with reduced risks of other types of cancer.

Pamela L Horn-Ross, Merrilee Morrow, and Britt-Marie Ljung, Diet and the Risk of Salivary Gland Cancer, American J Epidemiology 146(2):171-176 (15 July 1997) [Reprints: Dr Pamela L Horn-Ross, Epidemiology Program, Northern California Cancer Center, 32960 Alvarado-Niles Road, Suite 600, Union City CA 94587]

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