Prognostic impact of the subclassification of Müllerian cancer stage IV in the FIGO 2014 staging system with a focus of extra-abdominal lymph node metastases

Background: The International Federation of Gynecology and Obstetrics (FIGO) staging system for Müllerian cancer was changed in 2014. Our objective was to evaluate the prognostic impact of stage IV subclassification in this new staging system, especially focusing on extra-abdominal lymph node metastasis. Methods: Eighty-two patients with stage IV Müllerian cancer treated between 2005 and 2016 at our hospital were retrospectively analyzed. Data for the following clinicopathological variables were analyzed: (1) FIGO stage; (2) tumor stage; (3) lymph node status; (4) histologic type; (5) neoadjuvant chemotherapy; (6) optimal surgery; and (7) bevacizumab use. Survival analysis was performed using Kaplan–Meier curves, log-rank tests, and Cox proportional hazards models. Results: In accordance with the new classification, 28 and 54 patients were classified as FIGO IVA and IVB, respectively. In the Cox proportional hazards model, early-stage tumors (T1b–3b) and optimal surgery were statistically significant favorable prognostic factors. However, the new FIGO system did not discriminate prognostically between stage IVA and IVB. Median overall survival of stage IVB patients diagnosed with extra-abdominal lymph node metastasis only was better than that of stage IVA and stage IVB patients diagnosed with solid organ metastasis. Conclusions: In this analysis of the revised FIGO system of patients reclassified as FIGO stage IVA or IVB, no new prognostic information was obtained. There is a possibility that stage IVB patients diagnosed with extra-abdominal lymph node metastasis only can be classified as an earlier stage. Further modification of the FIGO staging system may be needed to improve the prediction of patient prognosis.