Researchers have found that the risk of developing lung cancer is directly correlated to the time of the day a smoker reaches for the first cigarette, one of the standard markers of addiction in both heavy and light smokers.

For this study, researchers analyzed statistical data from the Environment and Genetics in Lung Cancer Etiology (EAGLE) study, a large population-based case-control study designed to determine the genetic and environmental determinants of lung cancer and smoking habits within over 2,000 Italian individuals affected by different types of lung cancer. Broad epidemiological data such as smoking history, previous lung diseases, diet, anxiety or family history of lung cancer alongside clinical data such as stage, grade, histology, imaging and spirometry, were recorded for these patients.

Additionally, data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer screening trial in the United States, a large population-based randomized trial designed by the National Cancer Institute, was also analyzed.

In both studies, subjects were asked how soon after they wake up did they smoke the first cigarette of the day, with the responses categorized as 5 or fewer, 6-30, 31-60 and more than 60 minutes. Overall, the researchers concluded that the risk of lung cancer was significantly higher in smokers with shorter time to first cigarette, both male and female, with this correlation becoming stronger in current vs. former smokers and in lighter vs. heavier smokers, the later finding being somehow surprising.

Even though more studies are necessary, calculating the time to first cigarette can be useful to predict the risk of lung cancer development and to support programs in lung cancer screening and smoking cessation.