Breast Cancer Risk Among Female Health Professionals: A 35-Year Population-Based Longitudinal Cohort Study in Taiwan.

Introduction Breast cancer is the most frequently diagnosed cancer among women worldwide. Previous studies have found a higher risk in nurses but no clear relationship among other health professionals. This study aims to investigate the risks of incident breast cancer among female health professionals compared with that among nonhealth professionals in Taiwan. Methods This longitudinal observational cohort study included >35 years (1979–2016) of data from 4 nationwide population-based databases in Taiwan and identified matched cohorts with 1-to-2 propensity score matching between 277,543 health professionals and 555,086 nonhealth professionals. This study calculated total person-years for study subjects and compared breast cancer incidence between matched health and nonhealth professionals. Multivariable Cox proportional hazards and competing risk analyses were used, stratified by birth age, job tenure categories, and types of health professional license. Statistical analyses were conducted in 2019–2020. Results Health professionals had a significantly higher risk of breast cancer (hazard ratio=1.34, 95% CI=1.28–1.41; subdistribution hazard ratio=1.36, 95% CI=1.30, 1.42). Elevated risk of breast cancer incidence was associated with birth age, job tenure, and several health professional license types, including physician, pharmacist, registered nurse, midwife, medical technologist, and psychologist. Conclusions Elevated breast cancer risk was found overall in female health professionals. Regular ultrasonography for younger women and mammography for those aged >45 years may be necessary in the annual labor physical examination for female health professionals.