A recent study shows that some types of hormone replacement therapy (HRT) may affect breast cancer risk differently in younger women. While HRT overall was not linked to a higher risk of breast cancer before age 55, the type of hormone used played a key role.
Hormone replacement therapy helps ease menopause symptoms by replacing hormones like estrogen and progesterone, which decline as women approach menopause. Different HRT products contain estrogen alone, progestogen alone, or a combination of both.
Most research on HRT and breast cancer has focused on older women who have already gone through menopause. These studies found that combined estrogen and progestin therapy increases breast cancer risk.
To better understand risks for younger women — including those using HRT after surgery or during perimenopause — an international team led by the US National Institute of Environmental Health Sciences reviewed data on 459,476 women aged 16 to 54. About 2% of these women developed breast cancer before age 55.
Fifteen percent reported using hormone therapy, with estrogen-only and estrogen-plus-progestin therapies being most common. The study found estrogen-only therapy was linked to a 14% lower breast cancer risk, while estrogen plus progestin therapy was linked to a 10% higher risk.
The researchers noted that factors like age at first use, duration of therapy, and surgical history could influence these risks. Their findings provide useful guidance for doctors advising younger women about HRT.
Dr. Kotryna Temcinaite from the charity Breast Cancer Now said the study offers important insights. She explained that estrogen-only therapy may slightly reduce breast cancer risk, while combined therapy may increase it, especially if used for more than two years or if the woman still has her uterus or ovaries.
She emphasized that, for most people, the breast cancer risk linked to HRT is small and often outweighed by the benefits of symptom relief. However, the risk grows with longer use and is higher with combined HRT than estrogen-only therapy.
Dr. Temcinaite urged women to make informed choices about HRT in consultation with their healthcare providers. She also recommended that anyone with concerns contact their GP or Breast Cancer Now’s expert nurses through their confidential helpline.
Understanding these risks can help women weigh the benefits of hormone therapy against potential breast cancer concerns and make decisions best suited to their health and lifestyle.
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