Abstract 1750: Sleepduration across the adult lifecourse and risk of lung cancer mortality in Xuanwei, China
Authors: Wong Jason Y. , Chapman Robert S. , Hu Wei , Seow Wei Jie , Ji Bu-Tian , Bassig Bryan , Rothman Nathaniel , Lan Qing 
Published: July 2016

Abstract
Previous studies have implicated sleep duration as a risk factor for cancer incidence and all-cause mortality. However, to our knowledge, no study has addressed its relationship to lung cancer mortality among Chinese populations. Our objective was to evaluate the association between average sleep hours during various age periods, and risk of lung cancer mortality in rural Xuanwei, China.
Men and women who were born in 1917-1951 and lived in Xuanwei as of Jan 1 1976 were recruited for this cohort study. A total of 42,421 participants interviewed in 1992 contributed data to this analysis. The exposure was average sleep hours in the age periods of: 21-30, 31-40, 41-50, and 51-60 years, categorized as ≤ 7, 8 (reference), 9, and ≥10 hrs/day. The outcome was time to lung cancer mortality in 1992-2009. Cases diagnosed in the first two years of follow-up were excluded to avoid reporting bias due to early, undiagnosed disease. Fine and Gray models with age as the time scale were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI). Separate models were performed for each age period, and were adjusted for hours of indoor activities, respondent, secondary job, education, ethnicity, number of people and rooms in residence, fuel type and tons used, ventilation, smoking status and duration in men, mining work in men, and cooking age in women. Analyses were further stratified by sex and median age at baseline (≥ 61 and &lt; 61 years).
Non-linear relationships were found between sleep duration and lung cancer mortality. In men ≥61 years of age at baseline, ≥10 sleep hrs/day across adulthood was associated with substantially increased risks of lung cancer mortality compared to the recommended 8 sleep hrs/day [21-30 years: HR = 1.44 (95%CI: 1.00-2.07), 31-40 years: HR = 1.73 (95%CI: 1.15-2.59), 41-50 years: HR = 3.97 (95%CI: 2.64-5.97), and 51-60 years: HR = 3.55 (95%CI: 2.41-5.22). Furthermore, ≤ 7 sleep hrs/day in middle and later age was associated with significantly increased risks [41-50 years: HR = 1.56 (95%CI: 1.17-2.07) and 51-60 years: HR = 1.48 (95%CI: 1.15-1.92)]. Trends were similar in men &lt;61 years of age at baseline for the later age period. In women ≥61 years of age at baseline, ≥10 sleep hrs/day in ages 41-50 and 51-60 years was associated with substantially increased risks [HR = 2.45 (95%CI: 1.37-4.37) and HR = 2.59 (95%CI: 1.61-4.17)]. However, no statistically significant associations with ≤ 7 sleep hrs/day were found. Similar trends were observed for women &lt;61 years of age at baseline.
These findings suggest that both excessive and insufficient sleep may be risk factors for lung cancer mortality. Sleep deficit was associated with increased risks of lung cancer mortality in men, but less apparent in women. However, overabundance of sleep was found to be detrimental in both men and women, particularly during later ages. This study enriches the body of evidence implicating sleep duration in risk of lung cancer.
Citation Format: Jason Y. Wong, Robert S. Chapman, Wei Hu, Wei Jie Seow, Bu-Tian Ji, Bryan Bassig, Nathaniel Rothman, Qing Lan. Sleepduration across the adult lifecourse and risk of lung cancer mortality in Xuanwei, China. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1750.