How accurate is frozen section histology of pelvic lymph nodes in patients with endometrial cancer?

ObjectiveRecent prospective data support the trend towards systematic retroperitoneal lymphadenectomy in patients with high-risk endometrial cancer. Because para-aortic node involvement in the absence of pelvic node involvement is uncommon, a reliable finding of negative pelvic lymph nodes (PLN) at intraoperative frozen section examination might allow omitting para-aortic dissection. We analyzed the diagnostic accuracy of frozen section examination of PLN in patients with endometrial cancer.MethodsWe reviewed 131 patients with endometrial cancer who underwent surgery including systematic pelvic lymphadenectomy (n  = 101) or pelvic and para-aortic lymphadenectomy (n  = 27). Intraoperative frozen section examination of PLN was performed in 72 (55%) patients. Results of frozen section examination were compared with those of final histopathology and the diagnostic accuracy of frozen section examination of PLN was calculated. One pathologist measured the diameters of PLN metastases retrospectively.ResultsA total of 1063 and 2666 PLN were analyzed by frozen section examination and by final histopathology, respectively. PLN metastases were found in 7 cases (10%) at frozen section examination, and in 17 cases (24%) at final histopathology (false negative rate, 59%). No false positive cases were noted. The mean diameter of all PLN metastases at final histopathology was 4.3 mm, as compared to 9.0 mm for the metastases detected at frozen section analyses. The mean diameter of PLN metastases missed at frozen section examination was 2.0 mm.ConclusionIn this review at a single institution, intraoperative frozen section histology missed nearly two of three endometrial cancer patients with positive nodes. These results do not support tailoring the extent of lymphadenectomy according to the results of frozen section examination.