Background: Occupational risk factors for ovarian cancer have been investigated only to a limited extent. We conducted a case-cohort study to examine associations between occupational exposures and ovarian cancer in the textile industry.
Methods: We compared 261 incident ovarian cancer cases diagnosed between 1989 and 1998 with an age-stratified reference subcohort (n = 3199) from a cohort of 267,400 textile workers in Shanghai, China. Occupational exposures were assessed by job-exposure matrices designed for the textile industry, and estimates of quantitative cotton dust and endotoxin. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) with Cox proportional hazards modeling adapted for the case-cohort design.
Results: A decreased risk of ovarian cancer was associated with ever having worked in cotton manufacturing production (HR = 0.7; 95% CI = 0.4-1.0). An increased risk was associated with ever having worked in textile finishing (2.1; 0.9-5.0). We found an increasing risk of ovarian cancer associated with cumulative exposure to silica dust (for <10 years exposure, HR = 6.8 [CI = 0.6-76]; for > or =10 years, 5.6 [1.3-23.6]), although these results are based on only 8 exposed subcohort women (0.3%) and 4 cases (1.3%). We also detected inverse risk gradients for cumulative exposures to endotoxin when exposures were lagged by 20 years (in highest quartile, HR = 0.6 [CI = 0.4-1.1]).
Conclusion: Silica dust may increase the risk of ovarian cancer, and cotton dust and endotoxin may reduce risk.