Oral cancer and mouthwash.

As part of a case-control study in North Carolina involving 206 women with oral and pharyngeal cancers and 352 controls, questions were asked concerning the patterns of mouthwash use. No significant overall increase in risk was found among users; the relative risk, adjusted for snuff dipping and smoking habits, was 1.15 [lower, upper limits of the 95% confidence interval (95% Cl) = 0.8, 1.7]. The relative risk associated with mouthwash use was increased to 1.94 (95% Cl = 0.8, 4.7), however, among women abstaining from tobacco. Although consistent dose-response relationships were not observed for this subgroup, these findings and other reports of an increased risk among persons ordinarily at low risk of this disease raise the possibility that mouthwash may contribute to oral and pharyngeal cancers.