After hysterectomy, endometriosis patients used hormone therapy far more than others

Women with endometriosis who undergo hysterectomy face a distinct set of hormone-therapy decisions afterward, since removing the uterus and sometimes the ovaries brings on menopause while endometriosis itself can complicate which hormone regimen is appropriate. A study published this month in Climacteric, using Finland's national health registries, quantifies how these women's post-surgical hormone therapy use actually looks compared with women without endometriosis [s1].

The design

Researchers conducted a retrospective, register-based cohort study identifying women with a first surgical diagnosis of endometriosis, alongside a reference cohort without it, using Finnish national registries [s1]. The study included women aged 45 or younger who had both hysterectomy and bilateral oophorectomy (removal of both ovaries), and women older than 45 who had hysterectomy alone, with surgeries performed between 1996 and 2018 [s1]. Women with a history of thrombosis, breast cancer, or gynecological cancer were excluded [s1]. Hormone therapy use was tracked through Finland's national prescription reimbursement registry through the end of 2019 [s1]. The final cohort included 11,365 women: 1,748 aged 45 or younger and 9,617 older than 45 [s1].

What it found

Hormone therapy use after surgery was substantially more common among women with endometriosis than in the reference cohort, in both age groups. Among women 45 or younger, 94.3% of those with endometriosis used hormone therapy postoperatively, compared with 81.8% in the reference cohort [s1]. Among women older than 45, the gap was even wider in relative terms: 73.1% of women with endometriosis used hormone therapy, compared with 51.5% of the reference cohort [s1]. Both differences were statistically significant (p < 0.001) [s1].

Estrogen-only therapy was the most commonly used regimen overall, but use of combined estrogen-progestin therapy increased significantly over the study period [s1] — the paper's summary does not give the specific proportions of that shift, only that it was statistically significant.

Why endometriosis changes the hormone-therapy calculus

Endometriosis involves tissue similar to the uterine lining growing outside the uterus, and that tissue can respond to hormone therapy in ways that raise specific clinical considerations — including a documented, if uncommon, risk of endometriosis-related tissue transforming into cancer under estrogen-only therapy in women who've had a hysterectomy, which is part of why some clinicians favor adding a progestin even after the uterus itself is gone. The shift toward combined therapy documented in this study reflects, according to the authors, "evolving international guidance" on that specific point [s1] — meaning clinical practice for this subgroup of patients appears to be adjusting over time as understanding develops, rather than following the same estrogen-only default that's standard for hysterectomy patients without endometriosis.

What this doesn't establish

This is a descriptive registry study of prescribing patterns — it documents how often and what type of hormone therapy was used, not whether those choices produced better or worse outcomes for the women involved. It doesn't measure symptom relief, cancer risk, cardiovascular outcomes, or any other downstream health measure; it establishes prevalence and pattern, not effect. The data runs through the end of 2019 for prescriptions, even though surgeries were captured through 2018 — meaning more recent prescribing patterns after 2019 aren't reflected here. Finland's healthcare system and prescribing norms may not generalize directly to other countries' clinical practice.

What the authors say is needed next

The study's authors describe the high rate of hormone therapy use in this population as underscoring "the need for studies assessing its long-term outcomes in women with endometriosis" [s1] — an explicit statement that this descriptive study establishes the scale of the practice pattern without yet answering whether it's optimal.

What to watch

Long-term outcome studies specifically in women with endometriosis using different hormone-therapy regimens after hysterectomy, and whether the shift toward combined therapy documented here continues in more recent data. This article is not medical advice.

Sources

1. Menopausal hormone use after hysterectomy in endometriosis: a Finnish register-based study — Climacteric, 1 April 2026