Aromatase inhibitor therapy for endometrial stromal sarcoma - two-centre experience

Endocrine therapy is the recommended systemic treatment for steroid receptor positive endometrial stromal sarcoma (ESS). There is no current consensus on the optimal hormonal therapy for ESS. The literature offers several reports on advanced/recurrent/metastatic ESS patients treated with progestins, whereas data on the efficacy of aromatase inhibitors are scarce.

We retrospectively identified cases treated for ESS with aromatase inhibitors at our institutions. There were five patients with advanced or unresectable recurrent estrogen, progesterone and androgen receptor-positive ESS, treated with aromatase inhibitors: letrozole or anastrozole (at a daily dose of 2.5 mg and 1 mg, respectively), as first-line endocrine therapy in all but one case treated following progression with megestrol acetate.

Disease stabilization was achieved in four cases (80%), including two with long-term progression-free survival for up to 10 years attained under letrozole treatment, and one case after prior progestin treatment. During therapy, no substantial toxicity was observed.

Aromatase inhibitors as first- or second-line endocrine treatment achieve disease control in most steroid receptor positive ESS. Our series of cases is evidence of aromatase inhibitors efficacy as long-term endocrine treatment option for ESS patients.