Does estrogen affect meningiomas?

Estrogen's Effect on Meningiomas

Yes, estrogen does affect meningiomas, though its role is complex and less significant than progesterone. Progestin is known to increase meningioma risk and is associated with enrichment of PIK3CA mutations, while estrogen receptor expression is found in only about 6% of meningiomas compared to 76% for progesterone receptors. 1

Hormone Receptor Expression in Meningiomas

• Approximately 76% of meningiomas express progesterone receptors (PR), while only 6% express estrogen receptors (ER) 1
• The positive rate for PRs is much higher than for ERs in meningioma tissue samples 2
• Meningioma growth can be influenced by estrogen and/or progesterone binding to these receptors, though the exact mechanism remains unclear 2

Clinical Evidence of Hormonal Influence

• Meningiomas can grow rapidly during pregnancy, when both estrogen and progesterone levels are elevated 2
• Case reports document regression of multiple meningiomas after discontinuation of chronic progesterone therapy, suggesting a direct action of progesterone on tumor growth 3
• In vitro studies have shown that estradiol at physiologically relevant concentrations consistently stimulates meningioma cell growth 4

Therapeutic Implications

• Despite the presence of hormone receptors, clinical data on hormone-targeted therapy is inconclusive 1
• A phase III trial failed to show an effect of the PR inhibitor mifepristone on failure-free or overall survival of unresectable meningioma 1
• Testing for PR or ER expression as a basis for antihormonal treatment is discouraged for clinical routine and should only be considered in the context of clinical trials (ESCAT IVA) 1

Differential Effects by Sex and Hormone Type

• In laboratory studies, progesterone significantly inhibited the estradiol-induced growth stimulation in meningioma cultures 4
• Tamoxifen (an estrogen receptor modulator) significantly inhibited estradiol-induced growth stimulation in three of four meningioma cultures studied 4
• Interestingly, one study found that estrogen hormone replacement therapy was associated with 35% lower average tumor diameter and half the absolute growth rate compared to controls not receiving HRT 5

Clinical Management Considerations

• When evaluating patients with meningiomas, particularly at a younger age and with multiple tumors, a history of chronic hormone therapy should be obtained 3
• For patients with known meningiomas who require hormone therapy, careful monitoring is warranted, though preliminary research suggests estrogen-based HRT may not accelerate meningioma growth 5
• The presence of significant quantities of PR in a high percentage of tumors may have therapeutic implications for recurrent, malignant, or incompletely excised tumors 6

Pitfalls and Caveats

• The relationship between hormones and meningioma growth remains controversial and not fully understood 3
• Hormone receptor status alone should not dictate treatment decisions outside of clinical trials 1
• While hormone receptors are present, their functional significance may differ from hormone-dependent cancers like breast cancer 6