A suggested modification to FIGO stage I endometrial cancer

FIGO stage I endometrial cancers are divided into two substages, regardless of the presence or absence of lymphovascular space invasion (LVSI). The aim of this study was to investigate whether stratification based on the LVSI status would better predict mortality.

Using a multicentric database, we identified patients who underwent endometrial cancer operations between 2000 and 2010. The staging performance was quantified with respect to discrimination.

The study cohort included 508 patients (198 with LVSI-positive tumors and 310 with LVSI-negative tumors). The survival difference between the stage I patients with LVSI-positive and LVSI-negative tumors was highly significant (81% and 97%, respectively P=.009), whereas the difference between the stage I patients with tumors invading greater or less than half of the myometrium was not (87% and 96%, respectively P=0.09). The 5-year OS rates for the patients with LVSI-negative tumors invading less than half of the myometrium, with LVSI-negative tumors invading more than half of the myometrium and with LVSI-positive invading more than or less than half of the myometrium were 98%, 95%, and 81%, respectively (P=.03). Separating the LVSI-negative and LVSI-positive tumors would improve discrimination (concordance index, 77% vs. 75%, respectively, using the actual staging system).

A LVSI-positive status has a significantly worse prognosis. In this study, the distinction by LVSI status appears to be more relevant than the distinction between stages IA and IB for predicting survival in stage I endometrial cancer. This difference in prognosis would favor restaging these two entities.