Treatment of advanced uterine leiomyosarcoma with aromatase inhibitors

Aromatase inhibitors are sometimes used in the treatment of selected patients with uterine leiomyosarcoma (LMS), but there are few data assessing the efficacy of aromatase inhibitors in this setting.

We performed a retrospective electronic medical record review of patients with uterine LMS treated with an aromatase inhibitor at Memorial Sloan-Kettering Cancer Center between 1998 and 2008. We assessed progression-free survival (PFS) and objective response among patients with measurable disease and explored the correlation of hormone receptor status with outcome.

Forty patients with advanced or recurrent uterine LMS were treated with aromatase inhibitors. Thirty-four patients had measurable disease. Hormone receptor status for these patients was as follows: estrogen receptor (ER) positive-22, ER negative-9, ER unknown-3, progesterone receptor (PR) positive-10, PR negative-10, PR unknown-14. Aromatase inhibitors used were letrozole (in 74% of patients), anastrozole (21%), and exemestane (6%). Median PFS was 2.9 months (95% CI: 1.8-5.1). The 1-year PFS rate was 28% (95% CI: 11-48%) for ER and/or PR positive uterine LMS. Best objective response was partial response (PR) in 3/34 patients (9%) (all of whom were ER positive).

In this population of patients with mostly low-volume and ER positive uterine LMS, aromatase inhibitors achieved objective response in only 9%. Relatively prolonged PFS was observed among ER positive uterine LMS patients. In the absence of a no-treatment control group, the prolonged PFS cannot be attributed solely to the activity of the aromatase inhibitor treatment since it may reflect the underlying biology of low-volume, ER positive uterine LMS.