Annual Meeting of the NCI Cohort Consortium (Abstract Submission): Submission #10

Lightning Talks Abstract
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Presenter's First Name: : Karine 









Presenter's Last Name:: Alcala









Title (eg: professor, assistant professor, chair, etc):: {Empty}









Degree(s): M.S









Contact Email:: alcalak@iarc.who.int









Organization:: International Agency for Research on Cancer









Project Title:: Smoking history and lung cancer risk on four continents – Comprehensive analysis in 3,000,000 cohort participants from the Lung Cancer Cohort Consortium (LC3)









Additional Authors:
1. First Name: Xiaohsuang
   Last Name: Feng
   Degree(s): Ph.D
   Organization: International Agency for Research on Cancer
2. First Name: Mattias
   Last Name: Johansson
   Degree(s): Ph.D
   Organization: International Agency for Research on Cancer
3. First Name: Hilary
   Middle Initial: A
   Last Name: Robbins
   Degree(s): Ph.D
   Organization: International Agency for Research on Cancer










Abstract::
Background 

The extent to which lung cancer risk varies between individuals with similar smoking history in different parts of the world has not been described, nor has there been a comprehensive assessment of the importance of age at smoking initiation and cessation.  

Methods 

The study was conducted in 25 cohorts taking part in the Lung Cancer Cohort Consortium (LC3) and included longitudinal data on 2,879,895 participants from North America, Europe, Oceania, and Asia. We analyzed 38,722,397 person-years of follow-up during which 53,020 participants were diagnosed with lung cancer. We used Cox proportional hazards models to evaluate the association between lung cancer risk and age at smoking initiation and cessation, and flexible parametric survival models to estimate absolute risks of lung cancer. 

Results 

We found that age at smoking initiation is inversely associated with lung cancer risk, independently of differences in smoking intensity and duration, with 2.2-fold higher risk among those initiating smoking at age 15 or younger compared with those initiating after age 27. Lung cancer risk was much lower in individuals who quit smoking, and reached risk levels close to participants who never smoked among those who quit before age 30. North American participants had modestly higher 5-year risks than did participants in Asia and Europe. 

Discussion/Conclusion 

This comprehensive analysis highlights the consequence of elevated lung cancer risk for individuals who are exposed to tobacco smoking at an early age, as well as the importance of ceasing tobacco exposure as early as possible.