Purpose: Cigarette smoking is the major cause of laryngeal cancer. The time to first cigarette after waking in the morning is a behavior associated with several dimensions of nicotine dependence including the dose of smoke uptake. We hypothesized that a short TTFC increases the risk of laryngeal cancer.
Methods: The analysis was based on data from a hospital-based case-control study of laryngeal cancer. The current analysis included only subjects who were ever cigarette smokers, including 570 cases and 343 controls (832 whites and 81 blacks). Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression adjusting for smoking history and other potential confounders. Incidence data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 1975 to 2006 were analyzed for trends in laryngeal cancer.
Results: There was a dose-response relationship between TTFC and supraglottic cancer. Compared to subjects who smoked more than 60 min after waking, the adjusted odds ratio was 1.51 (95% CI, 0.63-3.61) for 30-60 min and 3.13 (95% CI, 1.56-6.30) for 0-30 min. No association was observed between TTFC and cancer of the glottis. In blacks, the TTFC was not associated with the risk of laryngeal cancer. Trends in SEER rates were similar for cancer of the glottis and supraglottis, indicating that the site-specific differences were not affected by unknown confounders.
Conclusion: A nicotine dependence behavior that is associated with cigarette smoke uptake increases the risk of cancer of the supraglottis larynx, but not glottis larynx.