Hormonal treatments in metastatic endometrial stromal sarcomas: the 10-year experience of the sarcoma unit of Royal Marsden Hospital

BACKGROUND: Hormonal manipulation is sometimes recommended in the treatment of metastatic endometrial stromal sarcoma, but there are few data assessing the efficacy of endocrine therapies in this subtype of uterine sarcomas. METHODS: We performed a retrospective electronic medical record review of patients with metastatic ESS treated with a hormonal agent at Royal Marsden Hospital between 1999 and 2011. We assessed progression-free survival (PFS), objective response and toxicity profile among patients with measurable disease. RESULTS: Thirteen patients with metastatic ESS were treated with hormonal therapies. Hormone receptor status (estrogen and progesterone receptors) was assessed in 9 out of 13 patients and in all of them it was moderately to strongly positive. Aromatase inhibitors (AIs) were prescribed as first endocrine line in 11/13 patients and progestins in the remainder, while in 2(nd) line treatment AIs were prescribed in 7/10 patients, followed by progestins and GnRH analogues. Median PFS for 1(st)line was 4.0 years (95% CI: 2.4 – 5.5 years) with 5-year progression-free rate of 30.8% (95% CI: 5.7 – 55.9%), both of which reflect the indolent natural history of ESS. Best objective response was partial response (PR) in 6/13 patients (46.2%; 95% CI: 19.2 – 74.9) and clinical benefit rate (defined as complete response + PR + stable disease ≥6 months) was 92.4% (95% CI: 64.0 – 99.8%; 12/13 patients). Median PFS for 2(nd) line was 3.0 years (95% CI: 2.0 – 4.1 years) with 2-year progression-free rate of 88.9% (95% CI: 68.3 – 100.0). CONCLUSIONS: In this cohort of metastatic ESS patients, 1st line endocrine treatment achieved objective response in 46.2% of them and clinical benefit in 92.4%. Tamoxifen and hormone replacement therapy should not be prescribed in patients with ESS due to their detrimental effects. Until more solid data are available, a reasonable recommendation would be that 1(st) line treatment with an endocrine treatment, preferably with an AI. Moreover, in view of the positive outcomes of our patients that received 2(nd)/3(rd)line endocrine treatments, all available hormonal options should be used in sequence in the management of ESS.