Lung cancer and annual mean exposure to outdoor air pollution in Crete, Greece. Reflections from a two decades big-database

Background: The increasing burden of lung cancer (LC) in Crete, Greece, has raised certain concerns about the potential association of environmental risk factors with LC. Aim: The aim of this study was to assess outdoor air pollution (OAP) and the risk for LC mortality for the first time in Crete using LC primary data. Methods: 5057 LC cases (diagnosed from 1992 to 2013) were obtained from the Cancer Registry of Crete (http://www.crc.uoc.gr) and followed up until 2014. The age-standardized incidence and mortality rates (ASIR) were calculated. Data on OAP indicators [particulate matter (PM)2.5, between 2.5 and 10 μm (PM2.5-10), PM10, PM2.5 absorbance (black carbon measure), nitrogen dioxide (NO2), and nitrogen oxides (NOx)] were collected. Spatial statistics were calculated and the binary logistic regression model was constructed at α=0.05 in IBM SPSS 24 and ArcMap 10.3.1. Results: LC in Crete accounts for 40.2 new cases/100 000/year for both sexes (ASIRmales=73.1 new cases/100 000/year; ASIRfemales=11.8 new cases/100 000/year). Annual median estimates of environmental concentrations in Crete were as follows: PM2.5=20.7 (±1.5) µg/m, PM10=38.9 (±2.5) µg/m, PM2.5-10=59.6 (±3.7) µg/m, PM2.5 absorbance=1.2 (±0.3)×10/m, NO2=15.2 (±3.8) µg/m, and NOx=20.1 (±4.9) µg/m. A statistically significant association was observed between OAP and LC mortality (mean correlation coefficient=0.75; P<0.05). The highest risk for 5-year LC mortality was found in the major urban centers and several south-east and north-west rural regions of Crete (relative risk=3.2, 95% confidence interval=1.6-4.7). Conclusions: OAP seems to be an important determinant of LC mortality. Targeted interventions should be performed in the high-risk areas.