Smoking and drinking in relation to oral cancer and oral epithelial dysplasia

Objective: Risks associated with smoking and drinking are not necessarily constant over the multistage pathway to oral cancer. We investigated whether smoking and drinking patterns differ for persons with oral cancer (OC) relative to those with oral epithelial dysplasia (OED), a precancerous condition. Methods: Incident cases of OC and OED were interviewed using a questionnaire containing questions on smoking and drinking. Odds ratios (ORs) compared the odds of smoking and drinking among persons with OC relative to OED. Results: No adjusted ORs for smoking achieved statistical significance; however, most were <1.0. The odds of OC relative to OED increased with drinking level; the adjusted OR for 19+ drinks/week was 3.03 (1.56-5.87). Age drinking began and years of drinking were not notably different for OC and OED cases; a higher proportion of OC cases reported discontinuing alcohol for 9+ years before diagnosis. Conclusions: The relationship between smoking and OED was at least as strong as that for smoking and OC, suggesting that smoking may have its greatest impact on oral carcinogenesis prior to malignant transformation. Drinking was more strongly associated with OC than OED, particularly at elevated consumption levels; the role of alcohol does not appear limited to a late-stage effect.