P3.09-24 The Concordance of Histological Diagnosis from Transbronchial Biopsy and Resected Specimen of Lung Cancers

Advances in radiological and diagnostic technics have improved the evaluation of pulmonary nodules, leading to an increase in preoperative histological diagnosis. For thoracic surgeons, it is important to know histological types of lung cancer preoperatively for the determination of surgical treatment strategy. The aim of this study is to evaluate the concordance of histological types between biopsy and resected specimens. A total of 653 patients with primary lung cancer were operated on in our hospital between January 2013 to March 2018. Among them there were 438 patients who underwent bronchofiberscopic examination, and 364 patients (83.1%) were diagnosed preoperatively as lung cancer. We retrospectively reviewed 316 patients who underwent both transbronchial biopsy (TBB) and then surgical resection for primary lung cancer between January 2013 to March 2018. We compared diagnosed histological types, examined the accuracy of preoperative diagnosis by TBB, and evaluated the concordance between those two kinds of specimens. In 302 of the 316 patients (95%), the histological types of lung cancer diagnosed from TBB matched those from resection specimens (κ=0.878). Concordance rate was the highest in adenocarcinoma (243/245; 99%), followed by squamous cell carcinoma (52/55; 95%). On the other hand, it was only 50% in neuroendocrine carcinoma (small cell carcinoma and LCNEC ± combined with adenocarcinoma / squamous cell carcinoma). Due to histological heterogeneity, 6 of 14 patients were diagnosed with different types of postoperative diagnosis, and four were due to the inconsistency of immunohistochemical (IHC) staining between biopsy and resected specimens. We considered that lung cancer has not only histological heterogeneity but also IHC heterogeneity. If larger samples are taken, the preoperative diagnosis of histological type could be more reliable.