A death certificate-based study of occupation and mortality from reproductive cancers among women in 24 US states

Occupational environment and ovarian cancer risk

OBJECTIVES

To investigate employment in an occupation or industry and specific occupational exposures in relation to ovarian cancer risk.

METHODS

In a population-based case-control study conducted in Montreal, Canada (2011-2016), lifetime occupational histories were collected for 491 cases of ovarian cancer and 897 controls. An industrial hygienist coded the occupation and industry of each participant's job. Associations with ovarian cancer risk were estimated for each of several occupations and industries. Job codes were linked to the Canadian job-exposure matrix, thereby generating exposure histories to many agents. The relationship between exposure to each of the 29 most prevalent agents and ovarian cancer risk was assessed. Odds ratios and 95% confidence intervals (OR (95% CI)) for associations with ovarian cancer risk were estimated using logistic regression and controlling for multiple covariates.

RESULTS

Elevated ORs (95% CI) were observed for employment ≥10 years as Accountants (2.05 (1.10 to 3.79)); Hairdressers, Barbers, Beauticians and Related Workers (3.22 (1.25 to 8.27)); Sewers and Embroiderers (1.85 (0.77 to 4.45)); and Salespeople, Shop Assistants and Demonstrators (1.45 (0.71 to 2.96)); and in the industries of Retail Trade (1.59 (1.05 to 2.39)) and Construction (2.79 (0.52 to 4.83)). Positive associations with ORs above 1.42 were seen for high cumulative exposure versus never exposure to 18 agents: cosmetic talc, ammonia, hydrogen peroxide, hair dust, synthetic fibres, polyester fibres, organic dyes and pigments, cellulose, formaldehyde, propellant gases, aliphatic alcohols, ethanol, isopropanol, fluorocarbons, alkanes (C5-C17), mononuclear aromatic hydrocarbons, polycyclic aromatic hydrocarbons from petroleum and bleaches.

CONCLUSIONS

Certain occupations, industries and specific occupational exposures may be associated with ovarian cancer risk. Further research is needed to provide a more solid grounding for any inferences in this regard.

[Professional risk factors associated with the cancer of the ovary. Literature review]

The aim of this work was to review the available literature on occupational risk factors associated with ovarian cancer. A PubMed search was performed using an algorithm with the following search terms: ovary, ovarian, exposure, work, occupation. Relevant articles were selected through assessment of titles and abstracts as well as through the reference lists of related articles. A total of 54 studies were selected for this review, including 17 studies on asbestos exposure and risk of ovarian cancer and, 16 studies on other occupational factors (5 cohort studies and 11 case control studies). An increased risk of ovarian cancer has been reported for several occupations (teachers, administration employees, nurses, religious workers) and various industrial sectors (biomedical research, telephony industry, hairdresser and beautician, printing factories) with inconsistent results. Moreover, in many of these studies, individual risk factors of ovarian cancers were not considered. Despite methodological limitations of published studies, a significantly increased risk for ovarian cancer associated with asbestos exposure have been consistently reported.

Occupational trichloroethylene exposure and cervical pathology: a case-control study

OBJECTIVES

Trichloroethylene (TCE) is suspected of association with elevated risk of cervical cancer. A case-control study was performed in a geographical area in which occupational TCE exposure is high. The study objective was to analyze the correlation between occupational TCE exposure and cervical cancer (including precancerous conditions).

METHODS

Case and control subjects were recruited by gynecologists. General and occupational data were collected by telephonic interviews. An industrial hygienist assessed occupational TCE exposure on a task-exposure matrix. Analysis focused on occupational TCE exposure at various levels and on cumulative dose. Multivariate analysis was performed to take account of the various risk factors.

RESULTS

In total, 67 case and 67 age-matched control subjects were included. Mean age was 36 years in both groups. Five of the possible general risk factors correlated significantly with cervical dysplasia or cancer: number of partners, history of genital or anal wart, interval between first period and first sexual relation, parity, and body mass index, the last three showing inverse correlation. Elevated risk was found in women who had had jobs as manual workers according to the PCS French classification (professions and socioprofessional categories), and production and related workers according to ISCO classification (International Standard Classification of Occupations), with odds ratios (ORs), adjusted on general and medical risk factors, of 7.68 [95% confidence interval (CI): 1.39-42.54] and 7.48 (1.30-43.24), respectively, among skilled service sector workers; the adjusted OR was close to significance, at 4.67 (95% CI: 0.92-23.67). No occupational sectors were significantly associated with elevated risk. In all, 17 (25.4%) case and 15 (22.4%) control subjects were exposed to TCE: raw OR = 1.17 (95% CI: 0.54-2.52), adjusted OR = 1.51 (95% CI: 0.42-5.41). There was no significant correlation between cumulative dose and exposure time.

CONCLUSIONS

The study found no significantly increased risk of cervical dysplasia or cancer associated with occupational TCE exposure.

Malignant tumors of the female reproductive system

This review summarizes the epidemiology of cancer of the female reproductive system and associated lifestyle factors. It also assesses the available evidence for occupational factors associated with these cancers. Cervical, endometrial, and ovarian cancers are relatively common, and cause significant cancer morbidity and mortality worldwide, whereas vulvar, vaginal, fallopian tube cancers, and choriocarcinomas are very rare. As several lifestyle factors are known to play a major role in the etiology of these cancers, very few published studies have investigated possible relationships with occupational factors. Some occupational exposures have been associated with increased risks of these cancers, but apart from the available evidence on the relationships between asbestos fibers and ovarian cancer, and tetrachloroethylene and cervical cancer, the data is rather scarce. Given the multifactorial nature of cancers of the female reproductive system, it is of the utmost importance to conduct occupational studies that will gather detailed data on potential individual confounding factors, in particular reproductive history and other factors that influence the body's hormonal environment, together with information on socio-economic status and lifestyle factors, including physical activity from multiple sources. Studies on the mechanisms of carcinogenesis in the female reproductive organs are also needed in order to elucidate the possible role of chemical exposures in the development of these cancers.

Occupation and risk of primary fallopian tube carcinoma in Nordic countries

The aetiology of primary Fallopian tube carcinoma (PFTC) is poorly understood. Occupational exposures may contribute to PFTC risk. We studied incidence of PFTC in occupational categories in the Nordic female population aged 30-64 years during the 1960, 1970, 1980/1981 and/or 1990 censuses in Denmark, Finland, Iceland, Norway and Sweden. Standardized incidence ratios (SIRs) for the years following inclusion in the study up to 2005 were calculated for 53 occupations; the expected numbers of cases were based on PFTC incidence in the national populations. Altogether 2,206 PFTC cases were detected during follow up via data linkages with the Nordic cancer registries. Significantly increased risks of PFTC were observed for smelting workers (SIR 3.99, 95% confidence interval 1.46-8.68, Obs = 6), artistic workers (2.64, 1.44-4.43, Obs = 14), hairdressers (2.18, 1.41-3.22, Obs = 25), packers (1.62, 1.11-2.29, Obs = 32), nurses (1.49, 1.14-1.92, Obs = 60), shop workers (1.25, 1.07-1.46, Obs = 159) and clerical workers (1.20, 1.07-1.35, Obs = 271) and these sustained over times and different Nordic countries. There was a nonsignificant increased risk for PFTC among welders, printers, painters and chemical process workers. The risk was significantly and consistently low for women working in farming (0.68, 0.47-0.95, Obs = 34) and among economically inactive women (0.88, 0.82-0.94, Obs = 833). The possible role of occupational exposures to the PFTC risks found in this study must be further evaluated in studies with a possibility to adjust for possible confounding factors, such as reproductive and life-style factors, which was not possible in our study.

Occupational exposures and the risk of ovarian cancer in Sweden

BACKGROUND

Studies of occupational exposures and ovarian cancer, often limited by few subjects or proportionate mortality data, have yielded inconsistent results.

METHODS

Swedish women employed in 1960, 1970, or during both years were followed from 1971 to 1989 using census data linked to nationwide cancer and death registries. A total of 9,591 ovarian cancer cases were identified among 1,670,517 women. Poisson regression was used to estimate the relative risk of ovarian cancer in specific occupational groups and in women exposed to particular occupational exposures defined by job exposure matrices. We lacked data on reproductive factors.

RESULTS

Jobs associated with elevated ovarian cancer rates in this and previous studies include dry cleaning, telegraph and telephone work, paper packaging, and graphic and printing work. In contrast to results of some previous studies, we found that hairdressers and beauticians were not at increased risk of ovarian cancer. Organic dusts, aromatic amines, aliphatic and aromatic hydrocarbons are suggested as specific etiologic agents.

CONCLUSIONS

In this large study, we have confirmed some results from smaller studies and identified some new relationships that need to be confirmed elsewhere.

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.

Tubal sterilization and use of an IUD and risk of cervical cancer

The relationship of tubal sterilization and use of an intrauterine device (IUD) to the risk of invasive squamous cell cervical cancer was evaluated in a case-control study carried out in Shandong, China, from 1989 to 1991. Patients (cases) were 272 women aged 30-77 years with newly diagnosed invasive squamous cell cervical cancer in Shandong Province Tumor Hospital. Controls were 893 randomly selected screened women matched to the cases by age (within 2 years) and county. A decrease in risk was observed in uses of an IUD, especially in long-term users under age 33. A nonsignificant decrease in risk in women under age 33 who had had a tubal ligation was also observed, especially in the first 10 years since the procedure. Tubal ligation and IUD insertion and removal provide opportunities to screen women for cervical cancer and reduce the risk of invasive disease.