Figure 3.

Lung cancer incidences in each category of time to first cigarette (TTFC) and smoking duration in the Environment and Genetics in Lung Cancer Etiology study (EAGLE). The figure shows the point estimate and 95% confidence interval of the absolute lung cancer rate per 100000 person-years (PY). The table under the figure shows the value of the point estimate (number of lung cancer case subjects). Incidence rates were estimated using a binomial linear model with 10 joint categories of TTFC and duration as well as the never smokers category. To evaluate whether the linear trend of lung cancer incidence with increased duration differed by TTFC statistically, we tested the interaction of TTFC and duration (treated as an ordinal variable) among smokers only. All statistical tests were two-sided.