Abstract
Menopausal hormone replacement therapy (HRT) increases the risk of breast cancer in Western countries; however, there are fewer reports from the Asian population, which has a lower incidence of breast cancer. A population-based retrospective cohort study was conducted by analyzing longitudinal National Health Insurance claim data of a 200,000-person national representative cohort. A total of 22,929 women aged ≥45 years in 1997 without previous diagnosis of breast cancer were enrolled and stratified into two birth cohorts born before or after 1933. HRT prescriptions were traced in outpatient data files and incident breast cancer cases were identified from 1997 to 2004. The Cox proportional hazards model was used to analyze breast cancer hazard ratio (HR). HRT users were censored after they discontinued HRT. The results showed that women born during 1933–1952 had a twofold increased risk of breast cancer (HR = 2.10, 95% CI = 1.47–3.00) compared with women born before 1933, when adjusted for HRT use. When adjusted for the birth-cohort difference, HRT users had significantly increased breast cancer HR versus non-users after four years of use (adjusted HR = 1.48, 95% CI = 1.03–2.13); the HR further increased to 1.95 (95% CI = 1.34–2.84) after eight years of use. In conclusion, a longer duration of current HRT use was associated with a higher risk of breast cancer independent of the birth-cohort difference.
Highlights
Both randomized controlled trials and observational studies conducted in Western countries have shown that menopausal hormone replacement therapy (HRT) increases the risk of breast cancer [1,2,3,4,5,6], but there are fewer reports from the Asian population [7,8,9]
It remains unanswered whether HRT use or a birth-cohort effect contributes to this phenomenon [18]
Compatible with the results of the Women’s Health Initiatives (WHI) study [1,2], our study found that long-term use of estrogen plus progestin increased the risk of breast cancer in women 45–64 years of age, but estrogen alone did not
Summary
Both randomized controlled trials and observational studies conducted in Western countries have shown that menopausal hormone replacement therapy (HRT) increases the risk of breast cancer [1,2,3,4,5,6], but there are fewer reports from the Asian population [7,8,9]. With the on-going Westernization of lifestyles, the incidence of breast cancer is increasing in Taiwan. There is an obvious birth-cohort difference observed, with the elderly generation retaining a low risk of breast cancer, while the younger birth cohort shows higher breast cancer incidence peaking at peri-menopausal ages [16,17]. It remains unanswered whether HRT use or a birth-cohort effect contributes to this phenomenon [18]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Environmental Research and Public Health
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
