Ultrastaging of negative pelvic lymph nodes to decrease the true prevalence of isolated paraaortic dissemination in endometrial cancer

Objective: This study aimed to determine the prevalence of occult pelvic lymph node metastasis in patients with endometrial cancer (EC) with isolated paraaortic dissemination who underwent pelvic and paraaortic lymphadenectomy. Methods: From 2004 to 2008, patients undergoing surgery for EC at our institution were prospectively treated according to a validated surgical algorithm relying on intraoperative frozen section. For the current study, we re-reviewed pathologic slides obtained at the time of diagnosis and performed ultrastaging of all negative pelvic lymph nodes to assess the prevalence of occult pelvic lymph node metastasis. Results: Of 466 patients at risk for lymphatic dissemination, 394 (84.5%) underwent both pelvic and paraaortic lymphadenectomy. Of them, 10 (2.5%) had isolated paraaortic metastasis. Pathologic review of hematoxylin-eosin–stained slides identified 1 patient with micrometastasis in 1 of 18 pelvic lymph nodes removed. Ultrastaging of 296 pelvic lymph nodes removed from the 9 other patients (median [range], 32 [20–50] nodes per patient) identified 2 additional cases (1 with micrometastasis and 1 with isolated tumor cells), for a total of 3/10 patients (30%) having occult pelvic dissemination. Conclusions: Ultrastaging and pathologic review of negative pelvic lymph nodes of patients with presumed isolated paraaortic metastasis can identify occult pelvic dissemination and reduce the prevalence of true isolated paraaortic disease. In the era of the sentinel lymph node (SLN) algorithm for EC staging, which incorporates ultrastaging of the SLNs removed, these findings demonstrate that use of the SLN algorithm can further mitigate the concern of missing cases of isolated paraaortic dissemination.