Clinicians should use caution when considering hormone replacement therapy (HRT) to manage menopause symptoms when prescribing it to women with a history of endometriosis, a study finds.

The study, published by Human Reproduction Update, said clinical trials and observational studies are needed to access the impact HRT can have on endometriosis recurrence and malignant transformation.

Endometriosis is commonly seen as a premenopausal disease, associated with estrogen hormone-dependent cell growth, progesterone hormone resistance, inflammation and genetic predisposition.

Estrogen, a hormone produced by the ovaries, is considered the central feature of endometriosis. Some studies have suggested that suppressing ovarian function by oral contraceptive pills or inducing menopause, which leads to a drastic reduction of this hormone, could cause disease regression and symptom relief, and could be seen as a way to cure endometriosis.

While this therapeutic strategy can relieve endometriosis-related symptoms, it can also trigger other symptoms that affect patients’ quality of life, such as hot flashes, vaginal dryness, and sleep and mood disturbances.

HRT has been widely used to control menopause symptoms, but it may have risks for women with a history of endometriosis. Based on estrogen and other hormones, HRT can reactivate tissue growth and cause a recurrence of endometriosis, and it can promote malignant transformation of residual endometriotic tissue.

In the study, “The management of menopause in women with a history of endometriosis: a systematic review,” the authors reviewed scientific studies of menopausal symptoms management in women with a history of endometriosis to identify treatment options and associated risks.

“Given the prevalence of endometriosis and the inevitability of eventual menopause in these women, this is clearly an important question that warrants robust, evidence-based guidelines,” the authors wrote.

Overall, the researchers analyzed data collected from 33 case reports and six observational studies and clinical trials. They found that endometriosis is not exclusively a premenopausal disease. Some studies reported cases of recurrent endometriosis, with abnormal bleeding and pain symptoms, in postmenopausal women taking some form of HRT.

Despite this clinical occurrence, the authors said it was unclear if HRT could be a risk factor for disease recurrence, mainly because controlled large-scale studies are lacking.

In addition, the authors highlighted the possibility of disease recurrence even in the absence of HRT. In these situations, other risk factors may play a role, such as high levels of estrogen, obesity, or incomplete surgery.

In malignant transformation, the authors said there are no studies indicating that HRT could be a risk factor. But more research is needed to enable better decision-making on menopause management.

“Although this review highlights potential risks of HRT, its substantial benefits should not be overlooked,” researchers wrote. “These women [endometriosis patients] deserve to have accurate, individualized and specific information about the risk of recurrence with different menopausal treatments, so that they can make an informed decision about their care.”