Diet and the risk of salivary gland cancer.

Cancer of the major salivary glands is relatively rare, and little is known about its etiology. The only established risk factors are radiation exposure and a prior cancer. The role of diet in the development of salivary gland tumors has not been addressed previously. The results from a population-based case-control study conducted in the greater San Francisco-Monterey Bay area examining the association between dietary intake and salivary gland cancer risk are presented. Of 199 cases diagnosed with salivary gland tumors between 1989 and 1993, 150 (75%) were interviewed. Nine cases were subsequently excluded based on review of pathology specimens. Of 271 controls identified through random-digit dialing and the Health Care Finance Administration files, 191 (70%) were interviewed. Eight cases and seven controls who over- or underreported dietary intake were excluded from analysis. Vitamin C intake of > 200 mg/day compared with < or = 100 mg/day was associated with a 60% decrease in salivary gland cancer risk (odds ratio (OR) = 0.40, 95% confidence interval (CI) 0.22-0.70). Inverse associations observed for carotene, vitamin E, and fiber from fruits and vegetables were diminished when adjusted for vitamin C intake. Fiber from been sources was associated with a 51% decrease in risk after adjusting for vitamin C intake (OR = 0.49, 95% CI 0.26-0.92 for > 1.4 g/day compared with < or = 0.4 g/day). Cholesterol intake was associated with elevated risk (OR = 1.67, 95% CI 1.2-2.4 for a 10% increase in calories from cholesterol). These findings suggest that preventive strategies developed for common chronic diseases, such as increased consumption of fruits and vegetables and limiting foods high in cholesterol, also may be effective in preventing these rare tumors.