Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study)

Abstract

Background:Night shift work, exposure to light at night (ALAN) and circadian disruption may increase the risk of hormone-dependent cancers.Objectives:We evaluated the association of exposure to ALAN during sleeping time with breast and prostate cancer in a population based multicase–control study (MCC-Spain), among subjects who had never worked at night. We evaluated chronotype, a characteristic that may relate to adaptation to light at night.Methods:We enrolled 1,219 breast cancer cases, 1,385 female controls, 623 prostate cancer cases, and 879 male controls from 11 Spanish regions in 2008–2013. Indoor ALAN information was obtained through questionnaires. Outdoor ALAN was analyzed using images from the International Space Station (ISS) available for Barcelona and Madrid for 2012–2013, including data of remotely sensed upward light intensity and blue light spectrum information for each geocoded longest residence of each MCC-Spain subject.Results:Among Barcelona and Madrid participants with information on both indoor and outdoor ALAN, exposure to outdoor ALAN in the blue light spectrum was associated with breast cancer [adjusted odds ratio (OR) for highest vs. lowest tertile, OR=1.47; 95% CI: 1.00, 2.17] and prostate cancer (OR=2.05; 95% CI: 1.38, 3.03). In contrast, those exposed to the highest versus lowest intensity of outdoor ALAN were more likely to be controls than cases, particularly for prostate cancer. Compared with those who reported sleeping in total darkness, men who slept in “quite illuminated” bedrooms had a higher risk of prostate cancer (OR=2.79; 95% CI: 1.55, 5.04), whereas women had a slightly lower risk of breast cancer (OR=0.77; 95% CI: 0.39, 1.51).Conclusion:Both prostate and breast cancer were associated with high estimated exposure to outdoor ALAN in the blue-enriched light spectrum. https://doi.org/10.1289/EHP1837

Effect of mistimed eating patterns on breast and prostate cancer risk (MCC‐Spain Study)

“…The latter was evaluated using geocoded residence of the subjects, Geographic Information System and modeling of light from digital photos taken by astronauts at the International Space Station as described in Garcia-Saenz et al. 30 Further adjustment to the above mentioned variables made minimal difference in risk estimates and these results are fully presented in Supporting Information Tables.…”

How Much Lighting is Required to Feel Safe When Walking Through the Streets at Night?

“…Outdoor lighting with predominant emissions in the short wavelength ("blue") part of the light spectrum may bring economic benefits, as it minimizes energy waste, while preserving visual performance in places where low-illuminance levels are needed [35]. Nevertheless, empirical evidence about the adverse impacts of such lighting on circadian rhythm and melatonin secretion in wildlife and humans cannot be ignored [36,37]. Concurrently, health and ecological impacts of exposure to the long wavelength (red) part of the light spectrum appear to be less severe [38,39].…”

Consequences of Artificial Light at Night: The Linkage between Chasing Darkness Away and Epigenetic Modifications

“…The incidences of breast and prostate cancers show close association with light pollution particularly in urbanized and industrialized regions [2,54]. Several epidemiological studies have found direct association between light pollution and incidence of breast cancer in women as well as prostate cancer in men [18,55,56]. Furthermore, the strong association between light pollution and cancer incidences displays divergent spatial disruption with higher incidences in urban compared with rural regions [57,58].…”

“…Some of the most disturbing effects of ALAN on health are metabolic dysfunction and cancer progression [2,16]. In mice and humans, several lines of evidence suggest a close association between ALAN levels and both obesity and breast cancer progression [17][18][19]. Here, we focus on ALAN as a novel environmental polluter that disrupts biological timing (temporal organization) and consequently may provoke severe health risk, particularly breast cancer development through epigenetic modifications.…”