Thèse en cours

Association entre le risque de cancer du sein et l'exposition à la lumière artificielle la nuit

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Auteur / Autrice : Nirmala Prajapati
Direction : Pascal Guénel
Type : Projet de thèse
Discipline(s) : Epidémiologie
Date : Inscription en doctorat le 30/09/2021
Etablissement(s) : université Paris-Saclay
Ecole(s) doctorale(s) : École doctorale Santé Publique
Partenaire(s) de recherche : Laboratoire : Centre de Recherche en épidémiologie et Santé des populations
Equipe de recherche : Exposome et hérédité
référent : Université Paris-Saclay. Faculté de médecine (Le Kremlin-Bicêtre, Val-de-Marne ; 2020-....)


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Exposure to electric light, especially artificial light at night (LAN), can disrupt sleep and biological processes controlled by endogenous circadian clocks, and have adverse health consequences. The health effects of light pollution have been little studied, while almost the entire European and American population lives under a sky polluted by night light. Among the health effects potentially related to exposure to LAN, breast cancer is a priority pathology because of its high incidence in developed countries. In addition, the International Agency for Research on Cancer has classified night work as a probable carcinogen, particularly for breast cancer, on the basis of carcinogenesis mechanisms related to circadian disturbances related to exposure to artificial light. A recent meta-analysis showed that the risk of breast cancer associated with indices of high exposure to LAN was increased, but this result needs to be strongly nuanced due to the sometimes questionable methods of assessing exposure and the lack of consideration of co-exposures in the studies considered. Estimating light pollution is often based on the use of satellite data to determine the areas where the light intensity is highest, but the images used are obtained by satellites in periods of clear cloudless weather, the latter having the effect of returning light to the ground and increasing the light intensity. In addition, blue light could have specific effects on cancer risk. It therefore seems interesting to be able to use indices of the spectrum of external blue light that have been specifically developed. Studies on the health effects of exposure to LAN should also take into account night work as a source of additional exposure to LAN, consider the role of sleep disorders as mediators of the relationship between LAN and breast cancer, and consider exposure to air pollution as a confounding factor in the LAN-breast cancer relationship. The objectives of the thesis are: 1) To define geographical indicators to characterize exposure to Artificial Light during the Night (LAN) in France. 2) Investigate the association between these geographic indicators and breast cancer risk, taking into account co-factors. The project is based on data from a large case-control study on breast cancers (CECILE study) and a cohort study in women (E3N study) involving a total of more than 6000 cases of breast cancer and more than 6000 control women. The use of data from the CONSTANCES cohort is also envisaged. An approach to qualify and quantify as finely as possible light pollution on the national territory currently and retrospectively (1990-2018) will be developed from data from satellite and International Space Station (ISS) imagery, as well as data from Weather France. Statistical analyses based on multivariate models will investigate associations between indicators of environmental exposure to LAN and breast cancer. The thesis will take place under the supervision of Pascal Guénel, researcher in epidemiology, in co-supervision with Elodie Faure, geomatician engineer.