title: The Risk of Breast Cancer in Women Using Menopausal Hormone Replacement Therapy in Taiwan.
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.
authors.affiliation: Department of Family Medicine, Taipei Veterans General Hospital, No.201, Sec. 2, Shi-Pai Road, Taipei 11217, Taiwan. ryliu@vghtpe.gov.tw.|School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong Street, Taipei 11217, Taiwan. ryliu@vghtpe.gov.tw.
authors.forename: Jui-Yao
authors.initials: JY
authors.lastname: Liu
authors.affiliation: Department of Family Medicine, Taipei Veterans General Hospital, No.201, Sec. 2, Shi-Pai Road, Taipei 11217, Taiwan. tjchen@vghtpe.gov.tw.|School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong Street, Taipei 11217, Taiwan. tjchen@vghtpe.gov.tw.
authors.forename: Tzeng-Ji
authors.initials: TJ
authors.lastname: Chen
authors.affiliation: Department of Family Medicine, Taipei Veterans General Hospital, No.201, Sec. 2, Shi-Pai Road, Taipei 11217, Taiwan. sjhwang@vghtpe.gov.tw.|School of Medicine, National Yang-Ming University, No.155, Sec. 2, Linong Street, Taipei 11217, Taiwan. sjhwang@vghtpe.gov.tw.
authors.forename: Shinn-Jang
authors.initials: SJ
authors.lastname: Hwang
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008593:Menopause; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors
keywords: Asian population; National Health Insurance Research Database; birth-cohort effect; breast cancer; menopausal hormone replacement therapy