Traffic-Related Air Pollution and the Risk of Invasive and Borderline Epithelial Ovarian Tumors

Abstract Background: Ambient air pollution may influence ovarian cancer risk but remains understudied. We examined long-term exposure to ambient nitrogen dioxide (NO2) in relation to the risk of invasive and borderline epithelial ovarian tumors. Methods: In a 2011 to 2016 population-based case–control study in Greater Montreal (Island of Montreal and North and South shores), 473 cases and 887 controls provided residential postal codes at study participation, which were linked to mean NO2 concentrations from a national land-use regression (LUR) model. Logistic regression estimated odds ratios (OR) and 95% confidence intervals (CI) for ovarian cancer overall. Polytomous logistic regression estimated associations for borderline and invasive tumors separately. Sensitivity analyses used NO2 concentrations from an alternative LUR model specific to the Island of Montreal. Results: For each interquartile range (IQR) increment (9.6 ppb) in ambient NO2, the OR (95% CI) of ovarian cancer overall was 1.07 (0.89–1.30) when adjusted for age, education, and area-level income. For borderline tumors, the adjusted OR (95% CI) per IQR of NO2 was 1.36 (0.99–1.87), whereas for invasive cancer it was 0.98 (0.79–1.21). Results were similar using NO2 estimates specific to the Island of Montreal and with adjustment for fine particulate matter. Conclusions: Our findings do not strongly support an association with invasive ovarian cancer but suggest that air pollution, as indicated by NO2 concentrations, may increase the risk of borderline tumors. Impact: This study addresses an important gap, given limited previous work on air pollution and ovarian cancer, and brings new findings as the first to analyze borderline and invasive tumors separately.