CONSUMPTION OF NITRATE, NITRITE, AND NITROSODIMETHYLAMINE AND THE RISK OF UPPER AERODIGESTIVE TRACT CANCER

Evidence from animal studies indicates that various N-nitroso compound s are carcinogenic. We investigated whether consumption of foods and b everages containing nitrosodimethylamine, nitrites, and nitrates affec ted the risk of laryngeal, esophageal, and oral cancer. In a populatio n-based case-control study in western Washington state, dietary consum ption of these substances was measured in 645 cases (169 laryngeal, 12 5 esophageal, and 351 oral) and 458 controls. After adjustment for tob acco, alcohol, and other known risk factors, there was a 52% reduction in the risk of upper aerodigestive tract cancer for individuals who c onsumed higher amounts of nitrate (upper tertile) compared with the lo west tertile (P < 0.001 for trend). Nitrate intake was associated with a reduction in cancer risk at all three sites. The reduction in the r isk of esophageal cancer with increasing nitrate consumption was more evident in frequent tea drinkers than in other subjects. There was no significant association between nitrite consumption and the risk of la ryngeal or oral cancer. However, for individuals with a history of can cer sores (an indicator of possible endogenous nitrosation), the risk of esophageal cancer was seven times greater in those with high versus low nitrite intake. Consumption of foods high in nitrosodimethylamine was associated with a 79% increased risk of upper aerodigestive tract cancer (P = 0.037 for trend). Cases consumed smoked fish more frequen tly than did controls [odds ratio (OR) = 3.03]. Daily intake of beer a nd of nitrite-containing meats were associated with an increased esoph ageal cancer risk (OR = 2.48 and 1.82, respectively). The odds ratio f or daily beer intake was also elevated for individuals with cancer of the oral cavity (OR = 1.79). Subjects who consumed higher amounts of a scorbic acid from foods and supplements were less likely to develop up per aerodigestive tract cancer than were individuals with lower ascorb ic acid intake (P = 0.003 for trend). These results indicate that nitr osation may be a factor in the etiology of upper aerodigestive tract c ancers, especially esophageal cancer.