Excellent Prognosis of Patients with Invasive Lung Adenocarcinomas Intraoperatively Misdiagnosed as AAH/AIS/MIA by Frozen Section.

Abstract Background Our previous study revealed that intraoperative frozen section (FS) could accurately differentiate invasive lung adenocarcinoma (LUAD) from pre-invasive lesions. However, few articles analyzed the clinical impact of FS errors such as underestimation of invasive adenocarcinomas, and whether complementary therapy was needed remains controversial. Research Question This study aims to investigate the prognosis of patients undergoing limited resection for invasive LUAD misdiagnosed as atypical adenomatous hyperplasia (AAH)/adenocarcinoma in situ (AIS)/minimally invasive adenocarcinoma (MIA) by intraoperative FS. Study Design and Methods From 2012 to 2018, data on 3031 patients undergoing sublobar resection of AAH/AIS/MIA diagnosed by FS were collected. The concordance rate between FS and final pathology (FP) was evaluated. To assess the clinical significance of FS/FP discrepancy, patients with invasive adenocarcinomas in final pathology were identified for prognostic evaluation. Results When AAH, AIS and MIA were classified together as a group, the overall concordance rate between FS and FP was 93.7%, and 192 (6.3%) patients got an upgraded diagnosis from the FP. Misdiagnosed invasive adenocarcinomas consisted of 94 (48.9%) lepidic predominant adenocarcinoma, 77 (40.1%) acinar predominant adenocarcinoma, 19 (9.9%) papillary predominant adenocarcinoma, one solid predominant pattern and one invasive mucinous adenocarcinoma. Among these patients, no positive N1, N2 lymph node was found. Moreover, the 5-year recurrence-free survival was still 100% even the final pathology turned out to be invasive adenocarcinoma. Interpretation Patients undergoing limited resection of invasive LUAD misdiagnosed as AAH/AIS/MIA by FS had excellent prognosis. Sublobar resection guided by FS diagnosis would be adequate for these underestimated invasive LUAD.