Mucinous differentiation is predictive of improved outcomes in low-grade endometrioid carcinoma.
Abdulfatah E, Sakr S, Morris RT, Munkarah AR, Barbuto D, Euscher E, Frauenhoffer E, Montiel D, Malpica A, Silva EG, and Ali-Fehmi R. Mucinous differentiation is predictive of improved outcomes in low-grade endometrioid carcinoma. Gynecol Oncol 2017; 145:121-122.
Objective: Endometrial carcinoma (EC) is the most common gynecological malignancy. Endometrioid carcinoma (EEC), the most common subtype, accounts for 75% of the cases and is often associated with squamous or mucinous differentiation. While the prognosis of pure mucinous carcinoma has been previously studied, the significance of mucinous differentiation in EEC is yet to be determined. The aim of this study was to correlate the presence of mucinous differentiation with clinicopathological features of a large multiinstitutional cohort of low-grade EEC (LGEEC) and to evaluate its impact on clinical outcomes. Method: A retrospective review of LGEEC (FIGO grades 1 or 2) (n = 593) diagnosed at 9 institutions between 1991 and 2011 was conducted to evaluate clinicopathological parameters including age, tumor size, stage, grade, depth and pattern of myometrial invasion (MI), necrosis, papillary architecture, squamous and mucinous differentiation, lymphovascular invasion (LVI), lymph node and cervical involvement, and clinical outcomes. Mucinous differentiation was defined as the presence of =10% cells with intracellular mucin. Data were analyzed using appropriate statistical analysis. Results: Patient median age was 61 years (22-91). Mucinous differentiation was identified in 38% (227/593) of the cases. Even though patients with mucinous differentiation were significantly older (N60 years) and their tumors showed more papillary architecture and MELF pattern of MI, they had a significantly lower recurrence rate (16% vs 23%, P = 0.044) (Table 1). While tumors with only papillary architecture showed poor prognosticators including larger tumor size (N6 cm), advanced stage, deep MI, necrosis, MELF pattern, cervical involvement, and LVI (P = 0.003, P = 0.001, P = 0.05, P = 0.001, P = 0.001, P = 0.05, and P = 0.001, respectively), combining both mucinous and papillary features showed significantly lower recurrence rate (14% vs 23%, P = 0.009). No difference in 5-year OS was detected in either group. Although not significant, the presence of MELF pattern in a separate analysis of patients with absence of mucinous differentiation showed worse outcome (mean DFI 122 vs 138 months). Conclusion: In this large series of LGEEC, the presence of mucinous differentiation was associated with better outcomes despite the presence of poor prognostic factors including old age, papillary architecture, and MELF pattern.