Past exposure to PM10 and lung cancer risk in the EAGLE case–control study

Within the EAGLE population-based case-control study, the present study aims to integrate previous analyses which suggested an increased lung cancer risk associated with particulate matter ≤ 10 μm (PM10) exposure estimated 2–5 years before diagnosis (year 2000), by considering pollutant levels estimated 12–15 years before diagnosis (year 1990), i.e., in a potentially more relevant time window. Odds ratios (OR) and 95% confidence intervals (CI) were calculated through multivariate unconditional logistic regression. Mean PM10 levels were higher in 1990 than in 2000 (68 vs. 46.6 μg/m3). Contrary to what we previously observed, among 1,665 cases and 1,808 controls we found no association between 1990 PM10 concentrations and lung cancer risk (OR: 0.96, 95%CI: 0.75–1.24). We further confirmed this difference also considering exposure from the two years combined, mutually adjusting for one another (0.89, 0.87–1.00 in 1990 and 1.49, 1.06–2.08 in 2000). The observed differences might be related to several factors: distinct methodologies used to estimate exposure, coarser granularity of 1990 exposure estimates, dissimilar levels in pollutant concentrations. However, our results might also suggest a greater relevance of more recent exposures in the carcinogenic process, thus contributing to the intriguing hypothesis that air pollution might act as a promoter of cancer development.