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.