Two most common types of areca chewing are noted in Taiwan: raw betel fruit with Piper betle inflorescence or folded in betel leaf. Piper betle inflorescence contains carcinogens, whereas betel leaf includes anticarcinogenic agents. One hundred and twenty-six esophageal squamous- cell-carcinoma patients and 279 healthy controls, all men, were analyzed. Areca chewers were 4.4 times (95% CI, 2.2-8.8) more likely to develop esophageal cancer than non-chewers. Sixty-five of the patients were areca chewers, of which, 61 (93.9%) chewed areca with Piper betle inflorescence, none chewed it with betel leaf and four (6.1%) chewed both. Of the 24 controls who were chewers, 10 (41.7%), three (12.5%) and 11( 45.8%) chewed areca with Piper betle inflorescence, betel leaf, and both, respectively. Multivariate analysis showed that subjects who chewed areca with Piper betle inflorescence were 24.4 times (95% CI 3.9-154.4) more likely to develop esophageal cancer than those who chewed areca with betel leaf or with both leaf and inflorescence. Our epidemiologic findings suggest parts of the same Piper plant contains carcinogenic and anticarcinogenic substances. ; 附設醫院外科部 ; 醫學院附設醫院 ; 期刊論文