Abstract 4655: Social jetlag and lung cancer incidence in the Alberta's Tomorrow Project: A prospective cohort study
Authors: Rana Benny , Harper Andrew , Shen-Tu Grace , Peters Cheryl , Brenner Darren , Morris Don G. , Yang Lin 
Published: September 2020

Abstract
Objectives: Increased lung cancer risk has been associated with markers of circadian disruption (e.g., overly short or long sleep duration, shift work, circadian gene mutation) in both human and animal studies. However, no study to date has reported the association of social jetlag, the misalignment between the internal clock and the socially required timing of activities, with lung cancer risk. We, therefore, aim to investigate this association in the Alberta's Tomorrow Project (ATP), a population-based prospective cohort study in Alberta, Canada, and the potential effect modification of smoking behavior.
Methods: Data on sleep patterns were collected on 19,436 (37.6% male) Albertans aged 35-69 years recruited from 2001-2015. Social jetlag was defined as the absolute difference in waking time between free day and workday that accounted for sleep debt, and categorized into three levels, 0 hours (32.52%), &gt;0-1 hours (32.44%), and &gt;1-4 hours (35.04%). Incident lung cancer cases were determined through linkage with the Alberta Cancer Registry by June 2018. Smoking behavior was defined as never smokers, former smokers, and current smokers. Hazard ratios (HR) were estimated using a series of Cox proportional hazards regressions, adjusting for age, sex, recreational physical activity, sitting time, daily calorie consumption, body mass index, marital status, education, employment status, total household income, smoking and drinking behavior, family history of cancer and preexistence of medical condition.
Results: A total of 117 incident lung cancer cases were identified during a medium of 9.6 years of follow-up, yielded 179,028 person-years. In the multivariable-adjusted model, a suggestive significant association between social jetlag and lung cancer risk was observed (&gt;1-4 hours vs. 0: HR=1.67, 95% CI: 0.96-2.92, p for trend = 0.047). The increased lung cancer risk with social jetlag was retrained and heightened among daily smokers (&gt;1-4 hours vs. 0: HR=2.72, 95% CI: 1.26-5.84, p for trend = 0.010), and attended to null among never smokers (&gt;1-4 hours vs. 0: HR=0.98, 95% CI: 0.15-6.54, p for trend = 0.91) and former smokers (&gt;1-4 hours vs. 0: HR=0.76, 95% CI: 0.27-2.12, p for trend = 0.63). Latency multivariate-adjusted model excluding those diagnosed with cancer within 2 years of baseline assessment returned similar results.
Conclusion: Increased risk for lung cancer was observed among adults who reported social jetlag, particularly daily smokers. Our findings suggest a potential lung cancer risk associated with switching sleep patterns between work and free days among smokers. Further studies are necessary to confirm these findings and elucidate the biological mechanisms.
Citation Format: Benny Rana, Andrew Harper, Grace Shen-Tu, Cheryl Peters, Darren Brenner, Don G. Morris, Lin Yang. Social jetlag and lung cancer incidence in the Alberta's Tomorrow Project: A prospective cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4655.