238MO - Long-term residential and workplace exposure to air pollution and breast cancer risk: A case-control study nested in the French E3N cohort from 1990 to 2011

Background

Air pollution, classified as carcinogenic to humans, is a major public health concern. Studies on breast cancer are scarce and remain inconsistent. We studied the association between breast cancer risk and long-term exposure to particulate matters (PM_2.5, PM₁₀) and nitrogen dioxide (NO₂) estimated at the womens' residential and workplace addresses.

Methods

We conducted a case-control study of 2419 cases and 2984 individually matched controls nested in the French prospective E3N cohort, over the period 1990-2011. Controls were matched to cases on department of residence, age (±1 year); date (±3 months), and menopausal status at blood collection. Annual mean PM_2.5, PM₁₀ and NO₂ concentration levels were estimated using a Land Use Regression (LUR) model (resolution 50m x 50m) and were assigned to women based on their geocoded residential and workplace addresses. The mean exposure was calculated for each woman from their inclusion into the E3N cohort to their index date (date of diagnosis of cases). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multivariate logistic regression models, for a 10 μg/m³ increase in PM_2.5, PM₁₀ and NO₂. Adjustment variables were selected from the literature, using a directed acyclic graph.

Results

The results showed a statistically significant linear increase in breast cancer risk related to mean exposure to PM_2.5 (adjusted OR 1.28; CI 1.00–1.63, for an increment of 10 μg/m³). A numerically increased risk was observed for PM₁₀ (adjusted OR1.09; CI 0.92–1.30) and NO₂ (adjusted OR 1.05; CI 0.97–1.13) for an increment of 10 μg/m³. No effect modification by menopausal status was observed (p interaction 0.99, 0.90, and 0.86 respectively for PM_2.5PM₁₀ and NO₂). Analyses by hormone receptor status showed a positive but not significant association for PM_2.5 for oestrogen receptor positive (ER+) breast cancer cases (adjusted OR 1.32; CI 0.97–1.79).

Conclusions

To our knowledge, this study is the first to investigate breast cancer risk associated with long term air pollution exposure at both, the subjects’ residence and workplace, estimated using a very fine spatial resolution LUR model. Future studies should consider exposure during commuting.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

INSERM.

Funding

ARC Foundation for Cancer Research (CANCAIR201601245), ANSES, French League against Cancer, Fondation de France.

Disclosure

All authors have declared no conflicts of interest.