Long-term medroxyprogesterone acetate therapy for low-grade endometrial stromal sarcoma

Low-grade endometrial stromal sarcoma (ESS) is a rare tumor. Endocrine treatment is frequently necessary, but treatment details have not been established.

Thirteen consecutive patients with low-grade ESS were examined clinicopathologically. All patients underwent surgery, and six were treated with a uniform regimen of medroxyprogesterone acetate (MPA) against residual or recurrent disease.

Of the 13 patients, 9 were in stage I, whereas the others were in advanced stages. The median follow-up period was 117 months (range 43-170 months). Six patients, including three with residual peritoneal dissemination and three with recurrent tumors, were treated with MPA. Six months after the initiation of treatment, 3 patients demonstrated a partial response, and 3 patients demonstrated stable disease. The median dosing period was 64 months (range 28-92 months). Five of the patients, including 2 patients who are alive with no evidence of disease and 3 patients who are alive with disease, continue with MPA therapy.

The clinicopathological characteristics of the low-grade ESS in this study are consistent with those reported in previous studies. MPA therapy with residual or recurrent disease achieved excellent disease control over a period of 5 years. These results indicate that MPA therapy might be considered as a therapeutic option for residual or recurrent low-grade ESS and perhaps chosen as a first-line therapy.