The predictive value of endobronchial ultrasonography with a guide sheath in the diagnosis of the histologic subtypes of lung cancer

Background Recent studies have shown differential response to chemotherapy among the subtypes of non-small cell lung carcinoma (NSCLC). Therefore, to accurately differentiate between the types of lung cancer is of paramount importance. Transbronchial biopsy using endobronchial ultrasonography with a guide sheath (EBUS-GS) is a promising method for the diagnosis of NSCLC. The purpose of this study was to evaluate the consistency between the types of lung cancer histologically diagnosed by bronchial biopsy or cytologically by EBUS-GS, and the final diagnosis of the resected specimen. Methods A retrospective analysis was performed on 203 patients having primary lung cancers diagnosed by EBUS-GS, who subsequently underwent curative pulmonary resection at the Hokkaido University Hospital between July 2003 and December 2011. In the present study, non-small cell carcinoma was defined as non-squamous cell carcinoma, and squamous cell carcinoma (Sq) was excluded. Results Of the 40 cases diagnosed as Sq by EBUS-GS, 37 cases were diagnosed as Sq, and 3 cases were diagnosed as non-Sq after surgical resection. Of the 159 cases diagnosed as non-Sq by EBUS-GS, 151 cases were diagnosed as non-Sq, 6 as Sq, and 2 as small cell carcinoma after surgical resection. These results showed that the positive predictive value of EBUS-GS in the diagnosis of Sq was 93%, and its positive predictive value in diagnosing non-Sq was 95%. Conclusions The pathological subtyping of NSCLC using small tissue and cytology samples obtained by EBUS-GS appears to effectively distinguish between Sq and non-Sq and is therefore considered useful in making a treatment decision.