Occupational exposure and incidence of female breast cancer at different stages in Taiwan.

OBJECTIVES

This retrospective cohort study aimed to investigate the associations between the incidence of female breast cancer (FBC) at different stages in various occupations among Taiwanese workers.

METHODS

We established employed and unemployed cohorts by linking the National Labor Insurance, National Pension Insurance, and Taiwan Cancer Registry databases, including 4,742,717 employed women and 2,124,616 women outside the paid workforce during 2010-2018. A total of 52,544 and 17,727 cases were identified among employed and unemployed women, respectively. Cox models were used to evaluate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for study outcomes.

RESULTS

Compared with the unemployed cohort, women in the employed cohort exhibited higher observed hazards of overall breast cancer (HR=1.16, 95% CI: 1.14-1.19), stage 0 (1.43, 1.36-1.50), stage 1 (1.28, 1.23-1.32), stage 2 (1.16, 1.12-1.20), and stage 3 (1.05, 1.00-1.10) disease, whereas a lower observed hazard was found for stage 4 breast cancer (0.85, 0.79-0.92). Female workers employed in the real estate industry exhibited a higher observed hazard of overall breast cancer (1.10, 1.01-1.20) than those employed in the education industry, whereas a similar trend was observed in the financial and insurance industry (1.07, 1.00-1.13). Higher observed hazards were also identified for several special occupational health hazard categories, although these estimates should be interpreted cautiously because of the limited precision of some estimates.

CONCLUSION

This study observed differences in stage-specific FBC incidence between employed and unemployed populations, as well as across various industries and special occupational health hazard categories.