Treatment of Severe Postmenopausal Endometriosis With an Aromatase Inhibitor

Objective: To treat an unusually aggressive case of recurrent postmenopausal endometriosis. Design: Case report. Setting: University of Texas Southwestern Medical Center (Dallas, Texas). Patient(s): A 57-year-old woman who presented with recurrent severe endometriosis after hysterectomy and bilateral salpingo-oophorectomy. Intervention(s): Oral administration of anastrozole (an aromatase inhibitor) (1 mg/d) and elemental calcium (1.5 g/d) for 9 months. Alendronate (a nonestrogenic inhibitor of bone resorption), 10 mg/d, was added to this regimen. Main Outcome Measure(s): Reduction in size of endometriotic lesion, pain relief, tissue levels of aromatase P450 messenger RNA, bone density. Result(s): Circulating levels of estradiol-17β were reduced to approximately 50% of the baseline value after the onset of treatment with anastrozole. Pain rapidly decreased and completely disappeared after the 2nd month of treatment. The 30 × 30 × 20-mm bright red polypoid vaginal lesion was reduced to a 3-mm gray tissue by the end of 9 months of treatment. Markedly high pretreatment levels of aromatase P450 messenger RNA in the endometriotic tissue became undetectable in a specimen obtained from a repeated biopsy after 6 months of treatment. Bone density of lumbar spine decreased by 6.2% after 9 months of treatment. Conclusion(s): This is the first description of the use of an aromatase inhibitor in the treatment of endometriosis. The short-term results were extraordinarily successful in elimination of pain and near-complete eradication of implants associated with severe endometriosis not responsive to other therapy. We conclude that the recently developed potent aromatase inhibitors are candidate drugs in the treatment of endometriosis that is resistant to standard regimens.