Light at Night and Risk of Pancreatic Cancer in the NIH-AARP Diet and Health Study.

Circadian disruption may play a role in carcinogenesis. Recent research suggests that light at night (LAN), a circadian disruptor, may be a risk factor for cancer. Moreover, LAN has been linked to obesity and diabetes, two risk factors for pancreatic ductal adenocarcinoma (PDAC). Here we examine the relationship between LAN and PDAC in an epidemiological study of 464,371 participants from the NIH-AARP Diet and Health Study. LAN was estimated from satellite imagery at baseline (1996) and incident primary PDAC cases were ascertained from state cancer registries. Cox proportional hazards models were used to estimate hazard ratios (HR) and 2-sided 95% confidence intervals (CI) for the association between quintiles of LAN and PDAC in the overall population stratified by sex. Over up to 16.2 years of follow-up, a total of 2,502 incident PDAC were identified in the cohort. Higher estimated LAN exposure was associated with an elevated PDAC risk. Compared to those living in areas in the lowest LAN quintile, those in areas in the highest quintile had a 27% increase PDAC risk (HR (95% CI), 1.24 (1.03, 1.49)), with similar risk for men (1.21 (0.96, 1.53)) and women (1.28 (0.94, 1.75)). In addition, stronger associations were observed in normal and overweight groups compared to the obese group (p for interaction = 0.03). Our results support the hypothesis that LAN and circadian disruption may be risk factors for PDAC.