Graveyard Shift, Light At Night Linked To Increased Risk.(for breast cancer)

2001 NOV 8 - (NewsRx.com & NewsRx.net) -- Women who work the graveyard shift may face an up to 60% increased risk of breast cancer, according to a Fred Hutchinson Cancer Research Center study.

Results of the study, the first population-based investigation of the relationship between breast-cancer risk and exposure to light at night as determined by sleep habits, bedroom lighting and graveyard-shift work, will be published in the Journal of the National Cancer Institute. The NCI funded the study.

Led by Scott Davis, PhD, a member of the Hutchinson Center's Public Health Sciences Division, the study is one of two independent investigations to be published in the JNCI that conclude sleep interruption, especially among women who work the night shift, is linked to a significant increase in breast-cancer risk.

"Although there have been a number of studies looking at the health effects of night-shift work, from heart disease to stomach ailments, this is the first that has looked comprehensively at both graveyard-shift work and light at night as independent risk factors for breast cancer," Davis said.

The study involved in-person interviews with more than 800 Seattle-area women who had been diagnosed with breast cancer, as well as a similar number of age-matched control subjects. The study assessed exposure to light at night and history of shift work, among other factors, during the 10 years prior to breast cancer diagnosis.

Davis and colleagues found that women who worked the graveyard shift at least once during the decade before breast-cancer diagnosis were at approximately 60% increased risk for breast cancer compared with those who did not work the graveyard shift. In addition, the risk of breast cancer significantly increased with each additional hour per week of graveyard-shift work.

The link between sleep, light at night and breast cancer may involve