Despite Earlier Concerns, Study Finds Hormone Therapy Does Not Cause Breast Cancer Recurrence

Menopausal hormone therapy has not been found to be associated with breast cancer recurrence, according to a recently published article in the Journal of the National Cancer Institute.¹

Breast cancer survivors can face a myriad of debilitating symptoms, including vaginal dryness, urinary tract infections, hot flashes, and night sweats.¹ Vaginal estrogen therapy and menopausal hormone therapy are potential treatment options, but the safety of these agents is still unclear, especially for women with estrogen receptor-positive disease.¹

Menopausal hormone therapy (also known as postmenopausal hormone therapy and hormone replacement therapy) has traditionally been used to alleviate common menopause symptoms that result from the loss of the natural hormones estrogen and progesterone during ­and after menopause.²

In the context of breast cancer, hormone therapy is recommended for women with hormone receptor-positive tumors.³ These tumors make up 2 out of every 3 breast cancers.³ Hormone therapy drugs such as tamoxifen stop estrogen from activating breast cancer growth, and it can also be used to lower the risk of developing breast cancer.³

Some physicians are hesitant to prescribe menopausal hormone therapy as a breast cancer treatment,¹ based on 2 trials conducted in the 1990s. These trials concluded that breast cancer patients had a greater risk of recurrent cancer if they took these hormones.¹ More recent studies have disproved these older trials, but they are limited by small sample size and short follow-up periods.¹

Researchers conducted the new study using longitudinal data from Danish postmenopausal women.¹ The women were diagnosed with early-stage estrogen receptor-positive breast cancer between 1997 and 2004.¹ Patients either received 5 years of hormone therapy (which is the typical duration of the treatment), or none.^1,3 Researchers then looked at possible associations between hormone treatment and their risk of causing mortality or recurrent breast cancer.¹

Of 8461 women, 1957 women were treated with vaginal estrogen therapy after diagnosis, 133 of whom received menopausal hormone therapy.¹ Researchers observed no increased risk of breast cancer recurrence or mortality among patients.¹

“This large cohort study helps to inform the nuanced discussions between clinicians and breast cancer survivors about the safety of vaginal estrogen therapy,” Elizabeth Cathcart-Rake, MD, said in an editorial accompanying the article. “These results suggest that breast cancer survivors on tamoxifen with severe genitourinary symptoms can take vaginal estrogen therapy without experiencing an increase in their risk for breast cancer recurrence. However, caution is still advised when considering vaginal estrogen for breast cancer survivors on aromatase inhibitors, or when considering menopausal hormonal therapy.”¹

References:

1. Hormone replacement therapy doesn't lead to breast cancer reoccurrence. Eurkealert. News Release. July 20, 2022. Accessed July 21, 2022. https://www.eurekalert.org/news-releases/958854
2. Menopausal Hormone Therapy and Cancer. National Cancer Institute. Website. July 17, 2018. Accessed July 21, 2022. https://www.cancer.gov/about-cancer/causes-prevention/risk/hormones/mht-fact-sheet
3. Hormone Therapy for Breast Cancer. American Cancer Society. Website. Accessed July 21, 2022. https://www.cancer.org/cancer/breast-cancer/treatment/hormone-therapy-for-breast-cancer.html