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Unopposed estrogen therapy and the risk of invasive breast cancer.
Arch Intern Med. 2006 May 08; 166(9):1027-32.AI

Abstract

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.

Authors+Show Affiliations

Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. wendy.chen@channing.harvard.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

16682578

Citation

Chen, Wendy Y., et al. "Unopposed Estrogen Therapy and the Risk of Invasive Breast Cancer." Archives of Internal Medicine, vol. 166, no. 9, 2006, pp. 1027-32.
Chen WY, Manson JE, Hankinson SE, et al. Unopposed estrogen therapy and the risk of invasive breast cancer. Arch Intern Med. 2006;166(9):1027-32.
Chen, W. Y., Manson, J. E., Hankinson, S. E., Rosner, B., Holmes, M. D., Willett, W. C., & Colditz, G. A. (2006). Unopposed estrogen therapy and the risk of invasive breast cancer. Archives of Internal Medicine, 166(9), 1027-32.
Chen WY, et al. Unopposed Estrogen Therapy and the Risk of Invasive Breast Cancer. Arch Intern Med. 2006 May 8;166(9):1027-32. PubMed PMID: 16682578.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Unopposed estrogen therapy and the risk of invasive breast cancer. AU - Chen,Wendy Y, AU - Manson,JoAnn E, AU - Hankinson,Susan E, AU - Rosner,Bernard, AU - Holmes,Michelle D, AU - Willett,Walter C, AU - Colditz,Graham A, PY - 2006/5/10/pubmed PY - 2006/5/24/medline PY - 2006/5/10/entrez SP - 1027 EP - 32 JF - Archives of internal medicine JO - Arch. Intern. Med. VL - 166 IS - 9 N2 - 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. SN - 0003-9926 UR - https://www.unboundmedicine.com/medline/citation/16682578/Unopposed_estrogen_therapy_and_the_risk_of_invasive_breast_cancer_ L2 - https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/10.1001/archinte.166.9.1027 DB - PRIME DP - Unbound Medicine ER -