No link between “light and Night” and breast cancer?
Results from a large cohort study provide no evidence to support the "intriguing but unproven" theory that circadian rhythm disturbance caused by exposure to light at night (LAN) increases breast cancer risk, say investigators. "Our study suggests that light levels at night do not materially increase a woman's risk of breast cancer, but further research will be needed before a definitive conclusion can be reached," lead author, Anthony J. Swerdlow, MD, PhD, professor of epidemiology at the Institute of Cancer Research in London, United Kingdom, said in a statement. However, a US expert on circadian rhythm disruption said the study is weak because exposure to light was misclassified, as well as self-recalled. The study analyzed prospective data from 105,866 women recruited to the ongoing Breast Cancer Now Generations Study shows no association between LAN and increased overall risk for breast cancer (hazard ratio [HR], 1.01). There was also n...