P02.05 Yield of Tumor Samples With A Guide-sheath in Endobronchial Ultrasound Transbronchial Biopsy For Non-small Cell Lung Cancer

Abstract

Adequate tumor tissue is required to treatment for non-small cell lung cancer (NSCLC). Transbronchial biopsy (TBB) by endobronchial ultrasonography with a guide sheath (EBUS-GS) is useful to diagnose peripheral lung lesions. We can choose two different sizes of GS kits—large and small. The data of tumor cell number obtained by TBB using different sizes of GS are limited. It is also unclear which lesion can be diagnosed by TBB with large GS. We investigated the utility of a large GS kit to obtain many tumor cells in patients with NSCLC. We further assessed the characteristics of lesions that could be obtained by TBB with large GS. Patients with a peripheral lung lesion and suspected of NSCLC were prospectively enrolled. They underwent TBB with a 5.9-mm diameter bronchoscope with a large GS. When the lesion was invisible in EBUS, we changed to a thinner bronchoscope and TBB was performed with a small GS. We compared the tumor cell numbers prospectively obtained with a large GS (prospective large GS group) and those previously obtained with a small GS (small GS cohort). The primary endpoint was the tumor cell number per sample, and we assessed characteristics of lesions that could be obtained by TBB with large GS. Biopsy with large GS was performed in 55 of 87 patients (63.2%), and 37 were diagnosed with NSCLC. The mean number of tumor cells per sample of the large GS group tended to be more than that of the small GS cohort (658±553 vs. 532±526, p=0.32) (Fig.1A. B; The comparison of the counts of the slide containing the largest number of tumor cells among five samples). The mean sample size of the large GS group was significantly larger than that of the small GS cohort (1.75 mm2 vs. 0.83 mm2, p<0.001). (Fig.1C. D; The comparison of the largest sample size of five samples) Logistic regression analysis indicated that the bronchus generation was significantly associated with the change to a thinner bronchoscope. Of the 12 lesions involving a third or less bronchus generation, 10 (83.3%) were diagnosed by GS-TBB with large GS. There was no significant difference in tumor cell number between two sizes of GS, although the sample size obtained by large GS was significantly larger than that of small GS. The 5.9-mm diameter bronchoscope with large GS can be used for lesions involving a third or less bronchus generation.