Project title: Shift Work and it's Association with Endometrial and Ovarian Cancer Among Women Textile Workers in Shanghai, China
Completed in: 2010
A growing number of women workers in the US and abroad regularly perfoRMS shift work. This warrants particular attention because of the growing body of evidence that shift work is associated with a number of adverse outcomes, including endocrine-related pathology such as diabetes, dysmenorrhea and breast cancer. Perhaps due to disruption in circadian regulation, individuals who work primarily during nighttime hours have lower concentrations of serum melatonin and it's urinary metabolites. Melatonin has antineoplastic effects, possibly via antimitotic, antioxidant, antiangiogenic and/or immune modulating activity. Epidemiologic studies demonstrate a positive association with both shift work and breast cancer, as well as with low serum melatonin levels and breast cancer. Fewer epidemiologic studies address the association of other endocrine-related cancer with shift work, such as ovarian and endometrial cancer. The objective of this study is to investigate associations between shift work and ovarian cancer and endometrial cancer among Shanghai women in the textile industry. Specifically, we aim to determine if the risk for these cancers increases with greater exposure to shift work among this population. Since enrollment in 1989 until 1998, 261 incident ovarian cases and 206 incident endometrial cases have been diagnosed. A subcohort will be randomly selected from among the entire cohort matched by age in 5-year age strata. Hazard ratios and 95% confidence intervals will be estimated with Cox proportional hazards modeling. Cumulative exposure to shift work will be categorized by years performing shift work. Estimates will be adjusted for age, parity, oral contraceptive use, IUD use and family history of endometrial, uterine, ovarian and colon cancer. The results of this study will contribute to the current body of knowledge regarding possible relationships between nonstandard work hour exposure and the risk of endometrial and ovarian cancer.