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PloS one2018; 13(5); e0197064; doi: 10.1371/journal.pone.0197064

Conjugated equine estrogen and medroxyprogesterone acetate are associated with decreased risk of breast cancer relative to bioidentical hormone therapy and controls.

Abstract: By the 1990s it became popular for women to use hormone therapy (HT) to ease menopause symptoms. Bioidentical estrogen and progesterone are supplements whose molecular structures are identical to what is made in the human body, while synthetic supplements are ones whose structures are not. After the Women's Health Initiative found that the combined use of the synthetics conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA) increased breast cancer risk, prescriptions for synthetic HT declined considerably. Since then there has been an increased interest in bioidentical HT; today there are a plethora of websites touting their benefits. However, no peer-reviewed articles support these claims. We performed a retrospective study with the objective of verifying the hypothesis that bioidentical HT is associated with decreased breast cancer risk than CEE & MPA. We searched The Northwestern Medicine Enterprise Data Warehouse for women who initiated HT use after age 50. Women who did not take any HT drug after age 50 served as controls. Nine HT protocols were investigated for breast cancer risk. Significant results include CEE Alone is associated with decreased breast cancer risk (HR = 0.31), Other Synthetic Estrogen Alone is associated with increased breast cancer risk (HR = 1.49), Bioidentical Estrogen Alone is associated with decreased breast cancer risk(HR = 0.65), CEE & MPA is associated with reduced breast cancer risk (HR = 0.43), and CEE & MPA is associated with reduced breast cancer risk relative to Bioidentical Estrogen & Progesterone (HR = 0.25). Our results indicate CEE & MPA is superior to bioidentical HT as far as breast cancer risk. Furthermore, this combination is associated with decrease of breast cancer risk, contrary to previous findings. Additional retrospective studies are needed to confirm our results.
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Publication Date: 2018-05-16 PubMed ID: 29768475PubMed Central: PMC5955567DOI: 10.1371/journal.pone.0197064Google Scholar: Lookup
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  • Extramural

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research indicates that the use of certain synthetic hormone therapies, specifically conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA), may be linked to a decrease in the risk of breast cancer. This contradicts popular belief and previous studies that associate these synthetic hormones with an increased risk of developing the disease.

Objective and Context

  • This research was designed to challenge the widely held assumption that synthetic hormone therapy (HT), specifically CEE and MPA, increases the risk of breast cancer in post-menopausal women.
  • While synthetic hormone therapy was increasingly prescribed in the late 20th century to ease symptoms of menopause, concerns arose over their safety after the Women’s Health Initiative documented an increased breast cancer risk associated with combined use of CEE and MPA.
  • Preferring a more ‘natural’ approach, many women transitioned to bioidentical hormone therapy, which involves the usage of supplements identically structured to human-made hormones.
  • However, despite the rise in popularity of bioidentical therapies, no peer-reviewed studies were found to support claims of increased safety or efficacy over synthetic hormones – thus instigating this research.

Methods and Results

  • Researchers conducted a retrospective study to compare various hormone therapy regimens and their impacts on breast cancer risks.
  • They drew from a pool of women who began hormone therapies after the age of 50 and employed those who did not take any hormone therapy drugs after 50 as a control group.
  • Nine different hormone therapy protocols were examined for their association with breast cancer risk.
  • The findings demonstrated that certain synthetic hormone therapies contradicted the traditional belief of increasing breast cancer risk.
  • CEE alone and in combination with MPA indicated an association with decreased breast cancer risk compared to controls and bioidentical estrogen and progesterone therapies.
  • Contrarily, other synthetic estrogens, when used alone, demonstrated an increased risk of breast cancer compared to the control.

Implications and Conclusions

  • The study concludes that synthetic hormone therapy, CEE and MPA specifically, may potentially offer a lower risk of developing breast cancer compared to bioidentical hormone therapy or no hormone therapy at all, contradicting previous findings.
  • However, the authors caution that these findings are preliminary and require further retrospective studies to confirm these results before revisions can be made to existing hormone therapy guidelines.

Cite This Article

APA
Zeng Z, Jiang X, Li X, Wells A, Luo Y, Neapolitan R. (2018). Conjugated equine estrogen and medroxyprogesterone acetate are associated with decreased risk of breast cancer relative to bioidentical hormone therapy and controls. PLoS One, 13(5), e0197064. https://doi.org/10.1371/journal.pone.0197064

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 13
Issue: 5
Pages: e0197064
PII: e0197064

Researcher Affiliations

Zeng, Zexian
  • Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Jiang, Xia
  • Department of Biomedical Informatics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
Li, Xiaoyu
  • Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America.
Wells, Alan
  • Department of Pathology, University of Pittsburgh and Pittsburgh VA Health System, Pittsburgh, Pennsylvania, United States of America.
Luo, Yuan
  • Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Neapolitan, Richard
  • Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.

MeSH Terms

  • Breast Neoplasms / chemically induced
  • Breast Neoplasms / epidemiology
  • Estrogen Replacement Therapy
  • Estrogens, Conjugated (USP) / adverse effects
  • Estrogens, Conjugated (USP) / therapeutic use
  • Female
  • Humans
  • Medroxyprogesterone / adverse effects
  • Medroxyprogesterone / therapeutic use
  • Menopause / drug effects
  • Middle Aged

Grant Funding

  • R01 LM011663 / NLM NIH HHS
  • R01 LM011962 / NLM NIH HHS
  • R01LM011663 / NIH HHS
  • R01LM011962 / NIH HHS

Conflict of Interest Statement

The authors have declared that no competing interests exist.

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Citations

This article has been cited 6 times.
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