Association between p53 immunostaining and cigarette smoking in squamous cell carcinoma of the esophagus

Background: it is generally accepted that cigarette smoking is closely asso ciated with esophageal squamous cell carcinoma. This study investigated the molecular targets of cigarette smoke in carcinogenesis of the esophagus. Methods: Seventy-four patients with esophageal squamous cell carcinoma (SCC ) were grouped according to daily cigarette consumption: heavy smoking grou p (group H) (n = 26), moderate smoking group (group M) (n = 39) and non-smo king group (group N) (n = 9). We compared p53 and retinoblastoma (RB) expre ssion among the three groups by immunohistochemistry. In addition, fresh tu mor tissues from 30 smokers with esophageal SCC were tested for p53 mutatio ns in exons 5-8 by direct sequencing. Results: Staining for the p53 product was positive in 65.4% of group H, 38. 5% of group M and 44.4% of group N. The frequency of positive staining in t he group H was significantly higher than in group M (p = 0.033) and in grou p M + group N (p = 0.034). The difference with respect to the frequency of overexpression of RE was not significant. The patterns of p53 base-pair mut ations in direct sequencing study were of five types, most commonly G:C to T:A transversion (35.3%). Conclusions: Our study suggests that one of the molecular targets of cigare tte smoke is the p53 gene. The pattern of p53 point mutations involved a wi de range of base-pair changes.