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Hormone Replacement Therapy Increases Risk of Breast Cancer Recurrence

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Hormone replacement therapy (HRT) increases the risk of breast cancer recurrence (the cancer coming back), so women with a history of breast cancer should not take HRT, according to a study.

The research was published online on Nov. 3, 2021, by the journal Breast Cancer Research and Treatment. Read the abstract of “Safety of systemic hormone replacement therapy in breast cancer survivors: a systematic review and meta-analysis.”

About hormone replacement therapy
About the study
What this means for you

About hormone replacement therapy

Many postmenopausal women take HRT to ease menopausal symptoms, such as hot flashes, night sweats, and fatigue.

There are two main types of HRT:

  • combination HRT, which contains the hormones estrogen and progesterone
  • estrogen-only HRT, which contains only estrogen

Medical guidelines say that women who have been diagnosed with breast cancer should not take HRT of any type. This is because the hormones in HRT can cause hormone-receptor-positive breast cancers to develop and grow.

Still, only a few small studies have looked at HRT use in women with a personal history of breast cancer. The researchers who did this study wanted to review all the available research to offer the most up-to-date information on the safety of HRT for women with a history of breast cancer.

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About the study

This study was a meta-analysis, a study that combines and analyzes the results of a number of earlier studies. In this case, the researchers analyzed the results of four studies that included 4,045 women with a history of breast cancer.

Overall, 2,022 women were randomly assigned to receive HRT and 2,023 were randomly assigned to receive a placebo. The placebo was a pill that looked just like the HRT pill but contained no hormones. The women joined the studies about 2 years after they were diagnosed with breast cancer.

It’s important to know that two of the four studies in the meta-analysis were stopped early because a short-term safety analysis found that using HRT increased the risk of breast cancer recurrence.

Overall, the researchers found that women who took HRT had a 46% higher risk of breast cancer recurrence versus women who didn’t take HRT. This difference was statistically significant, which means that it was due to taking HRT and not just because of chance.

The researchers also looked to see if HRT’s effect on recurrence risk was different for hormone-receptor-positive breast cancer and hormone-receptor-negative breast cancer.

Recurrence risk was:

  • 80% higher in women diagnosed with hormone-receptor-positive disease who took HRT
  • 19% higher in women diagnosed with hormone-receptor-negative disease who took HRT

“We observed that the use of HRT is associated with a significant increase in the risk of recurrence among women with history of [breast cancer],” the researchers wrote. “Therefore, this approach remains contraindicated in the [breast cancer] setting. Future research should be focused on alternative safe interventions to mitigate menopause-related symptoms for these patients.”

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What this means for you

If you’ve been diagnosed with breast cancer, this study offers important information and supports current recommendations: Women with a history of breast cancer should not take any type of HRT.

We know that menopausal symptoms can dramatically reduce quality of life for some women. If you’re experiencing troubling hot flashes, night sweats, or other symptoms, talk to your doctor about lifestyle changes, complementary and alternative medicine techniques, and non-hormonal medicine options that can help.

Lifestyle changes include:

  • identifying and avoiding hot flash triggers, such as stress, alcohol, caffeine, and smoking
  • maintaining a healthy weight
  • exercising daily to reduce stress

Complementary and alternative medicine techniques include:

  • acupuncture
  • meditation
  • yoga

Non-hormonal medicines include:

  • antidepressants such as Effexor (chemical name: venlafaxine) and Celexa (chemical name: citalopram)
  • high blood pressure medicines such as clonidine
  • anti-seizure medicines such as gabapentin and Lyrica (chemical name: pregabalin)
  • overactive bladder medicines such as oxybutynin

Learn more about Managing Menopausal Symptoms.

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Written by: Jamie DePolo, senior editor


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