Risk factors for oral and pharyngeal cancer in Shanghai, with emphasis on diet.

A population-based case-control study of oral and pharyngeal cancer was conducted in Shanghai, China, from 1988 to 1990, in which 204 (115 male, 89 female) incident cases and 414 (269 male, 145 female) controls were interviewed. Cigarette smoking and alcohol consumption, as well as occupational exposures to asbestos and to petroleum products and the use of kerosene stoves in cooking, were associated with increased risk of oral and pharyngeal cancer. In addition, more cases than controls reported having chronic oral diseases and false teeth. Dietary intakes of 42 major foods and selected salt-preserved or deep-fried foods during the past 10 years, ignoring any recent changes, were measured by a structured quantitative food questionnaire. After adjusting for known etiological factors, risks decreased with increasing intake of fruits, particularly oranges and tangerines, and some vegetables, including dark yellow vegetables and Chinese white radish. Men in the highest tertile of intake of these fruits and vegetables had about 30-50% the risk of those in the lowest tertile, with a less pronounced effect among women. A new finding was an excess risk associated with high consumption of salt-preserved meat and fish. The findings from this study provide further evidence that dietary factors play an important role in the development of oral and pharyngeal cancer.