[1105] Do Mitotic Index and Tumor Cell Necrosis Predict Patient Outcome in Low-Grade Endometrial Stromal Sarcomas? A Study of 33 Patients

Sarah Chiang, Koen Van de Vijver, Joana Loureiro, Marisa Nucci, Esther Oliva. Massachusetts General Hospital, Boston, MA; Maastricht University Medical Center, Maastricht, Netherlands; Brigham and Women's Hospital, Boston, MA

Background: Endometrial stromal sarcomas (ESSs) were historically divided into low- and high-grade based on mitotic index (MI), with brisk MI (>10/10 HPF) being considered a poor prognostic factor. Since then, there have been conflicting studies regarding the prognostic value of MI in these tumors. The presence of tumor cell necrosis (TCN) in ESSs has also been recently reported to correlate with aggressive behavior in tumors confined to the uterus. The aim of this study is to evaluate the utility of MI and TCN in primary uterine low-grade ESSs in predicting patient outcome.
Design: We reviewed all available slides of primary uterine low-grade ESS from 33 patients with clinical follow-up from 3 institutions. MI, as determined by number of mitoses/10 HPF averaged over 100 HPF, and presence or absence of TCN and infarct-type necrosis (ITN) were recorded. Progression-free and overall survival probability based on MI, TCN, and ITN was estimated by the Kaplan-Meier method.
Results: Twenty-one patients presented with stage I tumors, while 3, 4, and 5 patients had stage II, III, and IV disease, respectively. MI ranged from <1 to 22, <1 to 5, <1 to 26, and <1 to 5 per 10 HPF for stage I, II, III, and IV tumors, respectively. Sixteen tumors, including 10 stage I ESSs, showed MI <1/10 HPF, and in this group, 3 patients (stages I, II, and IV) experienced one or more relapses, and 2 died of disease (stages I and II). Of the 17 tumors with MI ≥1/10 HPF, 6 patients relapsed (4 stage I with MI ranging from 4 to 22/10 HPF, 1 stage III, 1 stage IV), and 1 died of disease (stage I with 22 mitoses/10 HPF). ITN was present in 12 ESS (9 stage I), and 5 of them also showed juxtaposed focal TCN. Among patients with tumors exhibiting TCN, only 2 had relapses (stage II and IV, both with MI <1/10 HPF) of whom 1 died of disease. Among patients with tumors showing either ITN or TCN, only 3 relapsed of whom 2 died of disease. Progression-free and overall survival data based on MI, TCN, and TCN or ITN were not statistically significant for tumors confined to the uterus or the entire cohort.
Conclusions: Although the number of patients is limited in this study, MI, TCN, and ITN do not appear to be predictive of tumor progression or outcome in patients with low-grade ESS, including those with stage I tumors.
Category: Gynecologic & Obstetrics

Monday, March 19, 2012 11:15 AM

Platform Session: Section E, Monday Morning


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