Risk of Breast Cancer in Post-Menopausal Women Using Hormone Replacement Therapy
ADUNE RATANAWICHITRASIN, M.D.*, KRIS BHODHISUWAN, M.D.*, WORAMIN REANSUWAN, M.D.*, SUPORNCHAI KONGPATANAKUL, M.D.**, SOMSRI RATANAWICHITRASIN, M.D.***
Affiliation : * Division of Head & Neck and Breast Surgery, Department of Surgery, ** Department of Pharmacology, *** Division of Clinical Epidemiology, Department of Research Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
Abstracts
Objective : To study the relationship of hormone replacement therapy (HRT) in post-meno
pausal women and risk of breast cancer.
Patients and
Method : The authors conducted a case-control study comparing the propor
tion of HRT used between breast cancer and non-breast-cancer women. Cases were breast cancer
patients who had natural menopause (excluded hysterectomy) and aged ;;::50-years-old from the Siriraj
Breast Cancer database (1983-1996). Controls were post-menopausal volunteers aged 50 year or
older who visited Siriraj Hospital for other purposes such as elderly clinics, health check, etc. After
informed consent, well-trained surgeons examined the women in the control group to exclude any
potential breast cancer. Patient characteristics and risk factors were collected.
Results : Of 1913 patients in the database, 623 were included as the cases. Data from 679
volunteers were collected for controls from May to December 1999. Among 1302 of the study popu
lation 58 women had ever used HRT (4.5%), which distributed to 3.2 per cent (20/623) in cases and
5.6 per cent (38/679) in controls. From univariate analysis, age, age at menopause, number of children,
habitat, education, contraceptive pills, familial history of breast cancer and HRT usage were asso
ciated with breast cancer (p-value<0.05). After multivariate forward stepwise logistic regression
=
analysis, there was no association between HRT use and breast cancer (adjusted odds ratio (OR)
=
0.61, 95% CI 0.31-1.20). In subgroups analysis, women who had older age, higher education level,
history of taking contraceptive pills, or positive familial history of breast cancer in second degree
relatives had a decreased risk of breast cancer, while those living outside Bangkok had an increased
risk.
Conclusion : Hormonal replacement therapy in post-menopausal women was not associated
with increased risk of breast cancer.
Keywords : Breast Cancer, Hormone, Replacement, Post-menopausal, Risk
