Diagnostic Accuracy and Usefulness of Intraoperative Margin Assessment by Frozen Section in Gastric Cancer.

BACKGROUND: Intraoperative frozen examination is clinically important for negative margin confirmation in cancer surgery. We investigated the diagnostic accuracy of frozen-section assessment and risk factors for positive resection margins by studying gastric cancer specimens from 1115 patients treated at our hospital.

METHODS: The results of gastric cancer patients who had undergone intraoperative margin assessment, employing frozen examination, with curative intent in our unit between 2000 and 2017 were retrospectively analyzed. Frozen section assessments were compared with the corresponding permanent section assessments to evaluate the accuracy, sensitivity, and specificity of the former. The causes of discordances between two assessments were examined. In addition, risk factors associated with positive margins were identified.

RESULTS: In total, 1241 specimens were obtained from the 1115 patients. The accuracy, sensitivity, and specificity of frozen-section assessments were 99.4%, 99.5%, and 97.8%, respectively. There were eight discordant cases. Two false-negative cases required another gastrectomy after final pathological diagnosis because of missed neoplastic cells. Six false-positive cases underwent unnecessary additional resection due to false positive results. In our frozen series, 89 cases had a positive margin on permanent section. Multivariate regression analysis of patients with positive surgical margins revealed large diameter (≥ 50 mm) and T4 tumor to be independent risk factors.

CONCLUSIONS: Intraoperative frozen examination is a highly accurate method that is useful for achieving negative margins. This procedure is especially recommended for patients with a tumor larger than 50 mm in maximum diameter or serosal invasion to confirm a negative margin.