P21, which regulates the cell growth cycle, is crucial for normal growth and differentiation. One polymorphism in the p 21 codon 31 produces variant proteins with an amino acid change (serine (ser) or arginine (arg) ). Although several epidemiologic studies have examined the effect of this polymorphism on cancer risk, the findings remain inconclusive, which has motivated us to evaluate the relationship between p21 codon 31 polymorphism and esophageal cancer risk. In this study, 128 cases of esophageal squamous cell carcinoma and 178 control cases from two hospitals in southern Taiwan were genotyped. Frequencies of arg/arg, arg/ ser and serlser were 23 (18.0%), 62 (48.4%) and 43 (33.6%) in carcinoma cases and 51 (28.6%) , 84 (47.2%) and 43 (24.2%) in control cases, respectively. After factoring out other potential contributing factors, patients with serlser or arg/ser were 2.17 times more at risk (95% CI = 1. 03-4.56) for developing esophageal cancer than those with arg/arg. Males ( n = 274) were found to have a slightly stronger association (adjusted OR = 2.45; 95% CI= 1.03-5.80). Although the sample size is relatively small, these findings suggest that a codon 31 polymorphism in p21 may be associated with the development of esophageal cancer. ; 附設醫院外科部 ; 醫學院附設醫院 ; 期刊論文