Epidemiology, Harvard T.H. Chan School of Public Health firstname.lastname@example.org.
Division of Sleep and Circadian Disorders, Brigham and Women's Hospital.
Department of Integrative Physiology, University of Colorado Boulder.
Channing Division of Network Medicine, Brigham and Women's Hospital and Harvard Medical School.
Channing Division of Network Medicine, Brigham and Women's Hospital.
Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School.
Slone Epidemiology Center, Boston University.
Circadian misalignment may increase the risk of developing hepatocellular carcinoma (HCC). The aim of this study was to examine the association between distance from time zone meridian, a proxy for circadian misalignment, and HCC risk in the U.S. adjusting for known HCC risk factors.
Surveillance, Epidemiology, and End Results (SEER) provided information on 56,347 HCC cases diagnosed between 2000 and 2014 from 16 population-based cancer registries in the U.S. Distance from time zone meridian was estimated using the location of each SEER county's Center of Population in a geographic information system (GIS). Poisson regression with robust variance estimation was used to calculate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for the association between distance from time zone meridian and HCC risk adjusting for individual-level age at diagnosis, sex, race/ethnicity, year of diagnosis, SEER registry, and county-level prevalence of health conditions, lifestyle factors, shift work occupation, socioeconomic status, and demographic and environmental factors.
A 5 degree increase in longitude moving east to west within a time zone was associated with a statistically significant increased risk for HCC (IRR 1.07, 95% CI 1.01-1.14, p = 0.03). A statistically significant positive association was observed among those <65 years old, while no association was observed among individuals ≥65 years old (p for interaction < 0.01).
Circadian misalignment from residing in the western region of a time zone may impact hepatocarcinogenesis.
Circadian misalignment may be an independent risk factor for HCC.