Occupational exposures and cancers of the endometrium and cervix uteri in Finland

Background: Endometrial cancer incidence rates are low in Asia and Africa and high in North America and Northern Europe. Cervical cancer is often the most common female cancer in developing countries, and infection with human papillomavirus (HPV) is its main risk factor. However, other factors, such as occupational exposures may modify the HPV-related risk. We conducted an exploratory register-linkage study in Finland to assess the role of occupational exposures on incidence rates of cancers of the endometrium and cervix uteri. Methods: Occupational risk factors for endometrial and cervical cancers were explored in a 25-year follow-up of female workers born 1906-1945 (N = 413,877) identified through the Population Census of Finland of 1970. Job titles in census records were converted to exposures of 31 occupational agents through a job-exposure matrix. Poisson regression models estimated relative risks (RR) for each agent, standardized for birth cohort, follow-up period, and socio-economic status. For each agent, the product of level and probability of exposure was calculated and subdivided in three categories: zero, low, and medium/high. Adjustment at the job title level was done for the turnover rate (endometrial and cervical cancers), mean parity, and age at first birth (endometrial cancer). Results: Endometrial cancer (2,833 cases) was associated with exposure to animal dust (RR 1.2, low level, 174 cases) and sedentary work (RR 1.3, high level, 145 cases). Cervical cancer (1,101 cases) was associated with exposure to aliphatic and alicyclic (RR 1.3, low level, 91 cases), aromatic (RR 1.2, low level, 318 cases; RR 1.4, high level, 41 cases), and chlorinated hydrocarbon solvents (RR 1.3, low level, 50 cases), silica dust (RR 1.2, low level, 251 cases), and wood dust (RR 1.2, low level, 249 cases). Conclusions: This study suggests that occupational exposures may be associated with increased risk of endometrial and cervical cancers.