Accepted for/Published in: JMIR Research Protocols
Date Submitted: Jun 25, 2019
Date Accepted: Jan 22, 2020
Chronic low-dose exposure to xenoestrogen ambient air pollutants and risk of breast cancer: study protocol of XENAIR Project
ABSTRACT
Background:
Breast cancer (BC) is the most frequent cancer in women in industrialized countries. Lifestyle and environmental factors, particularly endocrine disrupting pollutants have been suggested to play a role in BC risk. Current epidemiological studies, although not fully consistent, suggest a positive association of BC risk with exposure to several International Agency for Research on Cancer Group 1 air pollutant carcinogens, such as particulate matter (PM), polychlorinated biphenyls (PCB), dioxins, Benzo[a]pyrene (BaP), and cadmium. However, overall epidemiological studies are still scarce and inconsistent. It has been proposed that the menopausal status could modify the relationship between pollutants and BC, and that the association could differ according to the BC hormone receptor status.
Objective:
The XENAIR project will investigate the association of BC risk (overall and by hormone receptor status) with chronic exposure to selected air pollutants (PM, NO2, O3, BaP, dioxins, PCB153, and cadmium).
Methods:
Our research is based on a case-control study nested within the French national E3N cohort involving 6,490 incident invasive BC cases identified during follow-up from 1990 to 2010, and 6,490 matched controls. A specific questionnaire was sent to all participants to collect their lifetime residential addresses and information on indoor pollution. We will assess these exposures using complementary models (land-use regression, atmospheric dispersion, CHIMERE models) via a Geographic Information System. Associations with BC risk will be modelled using conditional logistic regression models. We will further study the impact on DNA methylation and interactions with genetic polymorphisms. Appropriate statistical methods, including Bayesian modelling, principal component analysis, and cluster analysis, will be used to assess the impact of multipollutant exposure. The fraction of BC cases attributable to air pollution will be further estimated.
Results:
The XENAIR project will contribute to increase current knowledge on the health effects of air pollution, and to better identify and understand environmental modifiable risk factors related to BC risk.
Conclusions:
The results will provide relevant evidence to governments and policy-makers to improve effective public health prevention strategies on air pollution. The XENAIR dataset can be used in future studies to investigate the effects of exposure to air pollution associated with other chronic conditions.
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