Intraoperative Examination of Sentinel Node in Endometrial Cancer (TRSGO-SLN-003)

Overview

More than half of the cases with macrometastatic sentinel lymph node (SLN) have non-SLN metastasis and leaving these nodes in-situ may impair the survival. This study assessed the diagnostic accuracy of intraoperative SLN frozen section examination and scrape cytology as a possible solution for management of SLN positive patients. Clinical early stage endometrial cancer patients who underwent SLN algorithm and intraoperative frozen section or scrape cytology to evaluate SLN status for metastasis were analyzed retrospectively. Intraoperative examination findings were compared with final pathology results and diagnostic accuracy of frozen section and scrape cytology were evaluated.

Frozen section: Lymph nodes up to 2 mm were embedded as a whole. Lymph nodes between 2-5 mm were cut in half along their long axis and nodes larger than 5 mm were sliced in neat, parallel slices at 2-3 mm intervals-slicing was perpendicular to the long axis of the node. Then whole of the SLNs were stained with hematoxylin and eosin (H\&E) and examined by frozen section. Scrape Cytology: SLNs were cut into 3-mm-thick pieces along their long axis. If the lymph node was smaller than 3 mm, it was cut in half. Both sides of the pieces were scraped separately by an edge of a glass slide or a lancet gently. Obtained materials were smeared immediately onto a slide and placed in ethanol for fixation. Then, all slides were stained with H\&E and examined. The results were reported to the surgeon as positive (metastatic) or negative with the numbers of lymph nodes. After intraoperative examination, lymph nodes were put into formalin solution and sent for final pathologic examination. Data analyses were performed using SPSS Version 21.0 (IBM Corporation, Armonk, NYC, USA). Shapiro-Wilk test was performed to determine whether the data were normally distributed. Descriptive statistics of continuous variables were compared between groups using Mann-Whitney U test. The Chi-square test or Fisher's exact test (when chi-square test assumptions do not hold due to low expected cell counts) were used to compare categorical variables between groups. Continuous variables were presented as median and min-max values, whereas categorical variables were presented as number and percentage. A p value of \<0.05 was considered statistically significant. Performance of each protocol to predict treatment success was assessed using confidence intervals with respect to sensitivity, specificity, positive predictive value, and negative predictive value.