Nitrogen dioxide (NO2) long-term exposure and breast cancer incidence: a meta-analysis followed by a health impact assessment

Abstract

BACKGROUND AND AIM: The epidemiological literature about the relationship of nitrogen dioxide (NO2) long-term exposure to breast cancer incidence has recently strongly evolved. We aimed to perform i) a meta-analysis of the studies considering this association, and, ii) using the dose-response function established, an assessment of the corresponding number of attributable cases in France and of the related economic costs. METHODS: We conducted a literature review and a random-effects meta-analysis corrected for publication bias of the epidemiological studies examining the association of NO2 long-term exposure with breast cancer incidence. Additional meta-analyses were stratified on menopausal status and on the hormone-receptor status of the tumor. The resulting dose-response function was combined with modeled NO2 atmospheric levels in 2013 for France to estimate the number of attributable breast cancers in France, and then the related economic costs. RESULTS:The literature review allowed identifying 11 relevant studies, providing 36 effect estimates, 21 and 8 of which according to menopausal and hormone-receptor status, respectively, and including 121,189 breast cancer cases among nearly 4 million women. The meta-analytical relative risk estimate of breast cancer incidence corrected for publication bias was 1.023 (95% CI, 1.005, 1.041). NO2 estimated effects appeared higher in premenopausal (1.059, 95% CI, 0.985, 1.138) than postmenopausal women (1.019, 95% CI, 0.993, 1.046), and higher for hormone-receptor positive (ER+/PR+, 1.045, 95% CI, 0.980, 1.114) than negative tumor subtype (ER–/PR–, 0.987, 95% CI, 0.885, 1.101). Assuming a causal effect of NO2, we estimated that 1,677 (95% CI, 374, 2,914) new breast cancer cases were attributable to NO2 annually in France, or 3.15% (95% CI, 0.70, 5.48) of the incident cases. The corresponding tangible and intangible costs were estimated to be 825 million Euros (570, 1,080) per year. CONCLUSIONS:These findings suggest that decreasing NO2 long-term exposure, or correlated air pollutants exposures, could decrease breast cancer risk. KEYWORDS: Breast cancer, economic costs, health impact assessment, meta-analysis, nitrogen dioxide (NO2)