Background: 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.
Methods: 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.
Results: 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).
Conclusions: 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.