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 (PM) 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 PM levels were higher in 1990 than in 2000 (68 vs. 46.6 µg/m). Contrary to what we previously observed, among 1,665 cases and 1,808 controls we found no association between 1990 PM 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.