 |
|
Unopposed Estrogen Therapy and the Risk of Invasive Breast Cancer
Wendy Y. Chen, MD, MPH;
JoAnn E. Manson, MD, DrPH;
Susan E. Hankinson, ScD;
Bernard Rosner, PhD;
Michelle D. Holmes, MD, DrPH;
Walter C. Willett, MD, DrPH;
Graham A. Colditz, MD, DrPH
Arch Intern Med. 2006;166:1027-1032.
Background Although short-term unopposed estrogen use does not seem to increase breast cancer risk, the effect of longer-term estrogen use remains unclear. We sought to assess the relationship between longer-term use of unopposed estrogen and the risk of invasive breast cancer over an extended follow-up period.
Methods Within the Nurses' Health Study, a prospective cohort study, we observed 11 508 postmenopausal women who had a hysterectomy and reported information on estrogen use at baseline (1980). The study population was expanded every 2 years to include women who subsequently became postmenopausal and had a hysterectomy, so that 28 835 women were included in the final follow-up period (2000-2002). Estrogen use was assessed from self-reported data on biennial questionnaires. The main outcome was invasive breast cancer.
Results A total of 934 invasive breast cancers were included in the analysis. Breast cancer risk increased with duration of unopposed estrogen use among longer-term users with the highest risk seen in cancers positive for estrogen receptor (ER+) and progesterone receptor (PR+). The multivariate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer with current use of unopposed estrogen for less than 5 years, 5 to 9.9 years, 10 to 14.9 years, 15 to 19.9 years, and 20 years or longer were, respectively, 0.96 (95% CI, 0.75-1.22), 0.90 (95% CI, 0.73-1.12), 1.06 (95% CI, 0.87-1.30), 1.18 (95% CI, 0.95-1.48), and 1.42 (95% CI, 1.13-1.77) (P for trend <.001). The risk of ER+/PR+ breast cancers was noted to be statistically significant after 15 years of current use (RR, 1.48; 95% CI, 1.05-2.07).
Conclusion Users of unopposed estrogen were at increased risk of breast cancer but only after longer-term use.
Author Affiliations: Channing Laboratory (Drs Chen, Manson, Hankinson, Rosner, Holmes, Willett, and Colditz) and Division of Preventive Medicine (Dr Manson), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Mass; Department of Medical Oncology, Dana Farber Cancer Institute (Dr Chen), Boston; and Departments of Epidemiology (Drs Hankinson, Willett, and Colditz) and Nutrition (Dr Willett), Harvard School of Public Health, Boston.
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
|
Increased incidence of lobular breast cancer in women treated with hormone replacement therapy: implications for diagnosis, surgical and medical treatment
Biglia et al.
Endocr Relat Cancer 2007;14:549-567.
ABSTRACT
| FULL TEXT
Hormones and Breast Cancer: What's the Story?
Brinton and Lacey
Cancer Epidemiol. Biomarkers Prev. 2007;16:1697-1699.
FULL TEXT
Management of cardiovascular risk in the peri-menopausal woman: a consensus statement of European cardiologists and gynaecologists
Collins et al.
Eur Heart J 2007;28:2028-2040.
ABSTRACT
| FULL TEXT
Critical assessment of new risk factors for breast cancer: considerations for development of an improved risk prediction model
Santen et al.
Endocr Relat Cancer 2007;14:169-187.
ABSTRACT
| FULL TEXT
Use of Oral Conjugated Estrogen Alone and Risk of Breast Cancer
Zhang et al.
Am J Epidemiol 2007;165:524-529.
ABSTRACT
| FULL TEXT
Risk Factors for Hormone Receptor-Defined Breast Cancer in Postmenopausal Women
Rosenberg et al.
Cancer Epidemiol. Biomarkers Prev. 2006;15:2482-2488.
ABSTRACT
| FULL TEXT
Estrogen-Only Therapy After Hysterectomy and Breast Cancer Risk
JWatch Women's Health 2006;2006:1-1.
FULL TEXT
|
