Standard markers of nicotine dependency include cigarettes smoked per day, duration of smoking, and cumulative exposure (pack years), but another marker of addiction, time to first cigarette (TTFC) of the day, may also be associated with the risk of getting lung cancer in both heavy and light smokers, according to a study published June 19 in the JNCI: Journal of the National Cancer Institute.
Fangyi Gu, Sc.D., M.D., of the Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, and colleagues analyzed questionnaire data from the Environment and Genetics in Lung Cancer Etiology (EAGLE) study of current and former smokers in Italy and the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer screening trial in the US. Subjects were asked about their smoking history and habits and to answer the question, "How soon after you wake up do you usually smoke your first cigarette of the day?" The responses were categorized as 5 or fewer, 6-30, 31-60, and more than 60 minutes.
In the sample of 3249 ever smokers from the EAGLE study, 1812 were lung cancer patients and 1437 were control subjects matched by residence, sex and age. In analyses adjusted for smoking intensity, duration and other lung cancer risk factors, compared to those with TTFC of more than 1 hour, the risk of lung cancer was statistically significantly higher in those with shorter TTFC. The association of TTFC with lung cancer risk was stronger in current vs. former smokers and, surprisingly, in lighter vs heavier smokers but not different between men and women. In analyses of the PLCO study, lung cancer risk increased in a borderline statistically significant trend.
The researchers conclude that although their results support the association of TTFC with lung cancer risk, prospective and screening studies are needed. They write, "Assessing TTFC may improve lung cancer risk prediction and could be useful in lung cancer screening and smoking cessation programs."