Anastrazole and oral contraceptives: a novel treatment for endometriosis

To establish the use of aromatase inhibitors as a therapeutic option for endometriosis.

Prospective open-label Food and Drug Administration phase 2 trial with Institutional Review Board approval.

Outpatient tertiary care centers.

Fifteen premenopausal patients with documented refractory endometriosis and chronic pelvic pain.

After a 1-month washout of endometriosis hormone therapies, women took 1 mg anastrazole (Arimidex; AstraZeneca, Wilmington, DE) and one tablet of 20 microg ethinyl estradiol/0.1 mg levonorgestrel (Alesse; Wyeth, Madison, NJ) daily for 6 months.

An analog pain scale recorded pelvic pain in daily diaries and surveys at baseline and after each treatment month. Side effects, blood counts, liver and renal function tests, cholesterol levels, and bone density were monitored.

Fourteen of 15 patients achieved significant pain reduction. Median pain scores decreased 55% after 6 months, while mean pain scores decreased 40%. Pain reduction comparing each treatment month to baseline achieved statistical significance. Average pain scores began dropping after only 1 treatment month and continued decreasing each additional month. No organ system experienced adverse effects. Estradiol levels were suppressed during treatment. Side effects were mild and improved over time.

Fourteen of 15 patients with refractory endometriosis achieved significant pain relief using anastrazole and 20 microg ethinyl estradiol/0.1 mg levonorgestrel with minimal side effects. This treatment for endometriosis is a promising new modality that warrants further investigation.