Artificial light at night and breast cancer risk: A systematic review and dose-response meta-analysis

BACKGROUND AND AIM: Artificial lightning has been suggested to be one of the environmental risk factor breast cancer onset and progression, based on epidemiologic evidence biological plausibility. Possible mechanisms include DNA damage, impairment melatonin estrogens secretion, inflammation, metabolic function. METHODS: We performed a systematic review epidemiological studies examining association between light-at-night (LAN) exposure we modeled shape relation using dose-response meta-analysis. After performing an online literature search up March 21, 2021, retrieved 16 eligible publications, including eight cohort case-control studies. RESULTS:In analyses comparing highest versus lowest LAN exposure, there was positive disease (risk ratio (RR)=1.10, 95% confidence interval (CI): 1.06-1.14), with relatively consistent associations observed in (RR=1.14, CI: 0.98-1.34) (RR=1.10, 1.06-1.14). In stratified analyses, RRs were similar for outdoor indoor while stronger RR among premenopausal women, women BMI category 20-25 kg/m2, estrogen-receptor cancer. The meta-analysis, implemented investigating only (for comparable assessment), indicated linear increasing 40 nW/cm2/sr after which plateau reached, especially women. CONCLUSIONS:Overall, this first assessing generally supports association. KEYWORDS: Light pollution, Cancer precursors, Environmental epidemiology, Non-chemical stressors