Long-term exposure to outdoor air pollutants and risk of pancreatic cancer in a large prospective U.S.-based cohort

Abstract Background Outdoor air pollutants have been inconsistently associated with pancreatic cancer incidence and mortality. Objective We investigated associations between outdoor fine particulate matter (PM 2.5 ) and nitrogen dioxide (NO 2 ) and pancreatic cancer risk. Methods We estimated historical pollutant concentrations at enrollment (1995–1996) residences in the NIH-AARP Diet and Health Study ( N = 486,431). We estimated hazard ratios and 95% confidence intervals (HR [CI]) for associations (continuous and categorical) with incident pancreatic cancer overall ( N = 4999) and pancreatic ductal adenocarcinomas (PDAC; N = 4708) in models adjusted for lifestyle and sociodemographic factors. Results We observed small, non-significant associations with pancreatic cancer overall (PM 2.5 $${\rm{HR}}_{{\rm{per}} \, 5 \, {{\upmu }}{\rm{g}} / {\rm{m}}^{3}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow> <mml:mi>HR</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>per</mml:mi> <mml:mspace/> <mml:mn>5</mml:mn> <mml:mspace/> <mml:mi>μ</mml:mi> <mml:mi>g</mml:mi> <mml:mo>/</mml:mo> <mml:msup> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msub> </mml:math> = 1.03[0.99–1.08]; NO 2 HR per 10 ppb = 1.02[0.99–1.06]) and with PDAC (1.03[0.98–1.08]; 1.02[0.98–1.06], respectively). We found no exposure-response across categories ( p -trend &gt; 0.05). The PM 2.5 association was apparent only among participants aged 55–64 years at enrollment ( p -interaction = 0.04). Significance Marginal associations between PM 2.5 and NO 2 and pancreatic cancer risk are consistent with a small number of prior studies. Impact This study builds on a small prior literature of associations between air pollution and pancreatic cancer risk. Our analyses in a large U.S.-based cohort revealed small, positive, but non-statistically significant associations between PM 2.5 and NO 2 and incident pancreatic cancer, and some heterogeneity was suggested by age. Future research incorporating enhanced exposure assessment across more demographically and geographically diverse populations may help to further elucidate these associations.