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 tumours. METHODS: In a 2011-2016 population-based case-control study in Greater Montreal (Island of Montreal, 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 (ORs) and 95% confidence intervals (CIs) for ovarian cancer overall. Polytomous logistic regression estimated associations for borderline and invasive tumours 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), adjusted for age, education and area-level income. For borderline tumours, the adjusted OR (95% CIs) per IQR of NO2 was 1.36 (0.99-1.87), while for invasive cancer 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. CONCLUSION: 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 tumours. 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 tumours separately.
Viau et al. (Mon,) studied this question.