Night Shift Work and the Risk of Breast Cancer

Abstract

Background: Breast cancer is the leading type of cancer in women, with 1.38 million new diagnoses in 2008 globally. It has been found that night work might increase the risk of breast cancer by exposure to light at night with subsequent melatonin suppression. Objective: To assess the association between night work and the risk of developing breast carcinoma. Methods: A literature review was conducted using Pubmed, Scopus and Web of Science to find relevant peer-reviewed articles. Results: A decrease in melatonin may increase the risk of breast cancer as a result of its protective abilities on regulating the immune system and on anti-mitosis actions among other protective abilities. The overall evidence from the studies examined indicates that frequent night work increases the risk for breast cancer. The risk is greater in women who worked for 20 years or more on night shifts. Conclusion: This research confirms that there is an association between night shift work and the risk of breast cancer. Further research with higher quality cohort studies is needed to confirm these results.