Is mucinous adenocarcinoma of the endometrium a risk factor for lymph node involvement? A multicenter case-control study.

PURPOSE: The purpose of this multicenter case-control study was to compare the demographic and clinical characteristics of patients with mucinous adenocarcinoma of the endometrium (MAE) and endometrioid endometrial carcinoma (EEC).
METHODS: A retrospective review of two cancer registry databases in Turkey was conducted to identify patients diagnosed with MAE between January 1996 and December 2012. Each patient was matched with a control EEC patient by age and tumor grade. Cases and controls were compared in terms of known risk factors for lymph node metastasis, disease-free survival (DFS), and overall survival (OS).
RESULTS: The analysis included 112 patients with MAE and 112 with EEC. No significant difference in baseline characteristics was evident between the two groups. Lymphovascular space invasion, deep myometrial invasion, cervical involvement, and tumor diameter did not differ significantly between the mucinous and endometrioid cases. Multivariate analysis confirmed that only mucinous histology (OR 2.2, 95 % CI 1.1-4.5; P = 0.02) was an independent predictor of lymph node involvement. Although the median DFS and OS tended to be better in the endometrioid group, the differences were not statistically significant. Routine appendectomy was performed in 52 (46.2 %) patients with MAE. No mucinous tumor of the appendix was identified.
CONCLUSION: Routine appendectomy is not necessary when the appendix is grossly normal at the time of surgery for MAE. Although the DFS and OS of EEC and MAE patients were similar, the risk of nodal metastasis in MAE patients was greater than that in ECC patients, and we thus suggest to perform retroperitoneal lymphadenectomy (both pelvic and para-aortic) for patients with MAE during the initial operation.