Hormone Replacement Therapy (HRT) is used to relieve menopausal symptoms, such as hot flashes and night sweats, by supplementing declining hormone levels. HRT typically involves estrogen, prescribed alone (estrogen-only therapy) for women who have had a hysterectomy, or combined with a progestogen (combined therapy) for those who still have a uterus. An ovarian cyst is a fluid-filled sac on or within an ovary. While most cysts are harmless during reproductive years, their presence after menopause often raises concern. This article explores the relationship between HRT use and the formation of ovarian cysts in the post-menopausal period.
Understanding Post-Menopausal Ovarian Cysts
After menopause, the ovaries become largely quiescent, stopping the regular cycle of follicle growth and egg release. Functional cysts common in reproductive years, such as follicular or corpus luteum cysts, are no longer expected. However, ovarian cysts can still occur in post-menopausal women, with a prevalence suggested to be 5% to 17%.
It is important to distinguish between simple and complex cysts, as this difference guides clinical management. Simple cysts are thin-walled, purely fluid-filled sacs that are almost always benign. Complex cysts contain solid components, internal walls (septations), or other irregularities. These features are associated with a higher risk of malignancy. Any ovarian mass found after menopause requires closer scrutiny because the risk of being cancerous is significantly higher in this age group compared to pre-menopausal women.
For a post-menopausal woman not on HRT, a small, simple cyst (typically less than five centimeters) has a very low risk of cancer. These often resolve spontaneously and are usually managed with a “wait and watch” approach involving follow-up ultrasound scans. Larger cysts or any cyst with complex features are treated with greater caution due to the increased probability of a pathological origin.
How Hormone Therapy Influences Cyst Formation
HRT can sometimes stimulate the ovaries, potentially leading to the formation of benign, functional cysts that would not otherwise occur. This stimulation is a minor effect of the supplemented hormones and is not associated with an increased risk of malignant cysts. The type of HRT regimen plays a role in this ovarian activation.
Cyclical or sequential combined HRT involves a period of progestogen-free days each month, mimicking a menstrual cycle. This regimen is more likely to cause minor follicular activity. This hormonal fluctuation can sometimes lead to the temporary development of small, fluid-filled functional cysts. These cysts generally resolve on their own, often within a few months, similar to functional cysts in younger women.
Continuous combined HRT involves taking both estrogen and progestogen daily without a break. This provides a more stable hormonal environment and is less likely to cause ovarian stimulation. Estrogen-only therapy does not introduce the cyclical fluctuations that can prompt functional cyst development. Overall, standard post-menopausal HRT has not been shown to significantly increase the risk of developing pathological ovarian cysts or ovarian cancer.
When to Be Concerned and Next Steps
The discovery of an ovarian cyst requires careful evaluation, often beginning with a transvaginal ultrasound. Concerning symptoms warranting immediate medical attention include persistent pelvic pain, bloating, a feeling of fullness, or sudden, severe abdominal pain. These symptoms could signal a cyst rupture or ovarian torsion and require evaluation regardless of HRT use.
The initial evaluation uses ultrasound to assess the cyst’s size and internal structure, classifying it as simple or complex. A blood test measuring the tumor marker CA-125 is frequently used alongside ultrasound findings for post-menopausal women. While CA-125 levels can be elevated for benign reasons, a high value combined with a complex cyst increases the suspicion for malignancy.
For small, simple cysts without concerning features, the usual protocol is a “wait and watch” approach. This involves a repeat ultrasound in a few months to confirm the cyst has resolved or remained stable. If the cyst is thought to be a benign, HRT-related functional cyst, a temporary four-week pause in the HRT regimen may be recommended to see if it shrinks. Complex, persistently large cysts, or those associated with a high CA-125 level, require referral to a specialist for further management, possibly including surgical removal.