Patients and diagnosis
The median age was 74 years (range; 41-91), and 62 (62%) were male (Table 1). Table 2 shows the diagnostic results of all patients. Bronchoscopy confirmed malignancies in 94 cases (94%), with adenocarcinoma accounting for 59 cases (59%). Forceps biopsy was not performed in two cases due to time restraints.
Diagnostic yield
The mean tumor diameter using computed tomography (CT) images was 37 mm (range 11-127 mm), and the average number of biopsies was 2.4 for forceps biopsy and 1.1 for TBLC, activated for 5.0 seconds (range; 3-7 seconds) of mean freezing time. The mean sample size of TBLC was 9.77 mm2 (range 0.86-44.31 mm2).
TBLC diagnosed 86 cases (86%), forceps biopsy diagnosed 81 of 98 cases (82.7%), and cytology diagnosed 82 cases (82%), (Table 3). The diagnostic yield increased to 94% when all procedures were combined. Six cases were unable to be diagnosed by all techniques (6.0%). There was no significant difference in the diagnostic yield between TBLC and forceps biopsy (P=0.206).
The location of biopsies and the diagnostic yield for each procedure are shown in table 3. In the upper lobe, the diagnostic yield for brushing cytology and TBLC was 80.0% (44/55, each), while forceps biopsy was 84.9% (45/53). There was no significant difference in the diagnostic yield between forceps biopsy and TBLC. In the middle/lingular lobe, the diagnostic yield for brushing cytology and TBLC was 87.5% (7/8 each), while forceps biopsy was 100% (8/8). In the lower lobe, the diagnostic yield of brushing cytology was 83.8% (31/37), forceps biopsy was 75.7% (28/37), and TBLC was 94.5% (35/37). The diagnostic yield for TBLC was significantly higher than that of forceps biopsy in the lower lobe (P=0.0082).
Table 3 shows echogenic findings by radial EBUS and the diagnostic yield of each technique. When echo findings were within the lesion, the diagnostic yield for brushing cytology and forceps biopsy were both 83.9% (73/87), while TBLC was 87.4% (76/87). When echo findings were adjacent to the lesion, the diagnostic yield for brushing cytology was 81.8% (9/11), while forceps biopsy was 70.0% (7/10). The diagnostic yield for TBLC was 81.8% (9/11). When echo findings visualized mixed blizzard signs in two cases, the diagnostic yield of brushing cytology was 0% (0/2), forceps biopsy was 100% (1/1), and TBLC was 50.0% (1/2).
Table 3 also shows the diagnostic yield for each procedure and location in cases where GS was used. The total diagnostic yield for brushing cytology with GS was 82.5% (66/80). For the brushing cytology subgroup, the diagnostic yield for the upper lobe, middle/lingular lobe, and lower lobe was 78.6% (33/42), 85.7% (6/7), and 87.1% (27/31), respectively. The total diagnostic yield for forceps biopsy with GS was 84.6% (66/78). For the forceps biopsy subgroup, the diagnostic yield of the upper lobe, middle/lingular lobe, and lower lobe was 87.5% (35/40), 100% (7/7), and 77.4% (24/31), respectively. The total diagnostic yield for TBLC with GS was 88.8% (71/80). For the TBLC subgroup, the diagnostic yield of the upper lobe, middle/lingular lobe, and lower lobe was 83.3% (35/42), 85.7% (6/7), and 96.8% (30/31), respectively.
The diagnostic yield of TBLC without GS was 75% (15/20). There was no significant difference in the diagnostic yield for TBLC with or without GS (P=0.145).
Adverse events
There were two cases of severe bleeding during TBLC. In one case, a Fogarty balloon catheter was effective but active bleeding continued after deflation of the balloon. An endobronchial Watanabe spigot was placed to stop the persistent bleeding. In the second case, active bleeding with a volume of about 500 ml was suctioned immediately after TBLC due to the balloon catheter displacement. This patient suffered from hypoxemia and hypotension. After haemostasis by wedging the bronchoscope to the access bronchus and changing to the side lying position, the patient recovered from hypoxia and was transferred to the intensive care unit and extubated the following day.
Next-generation sequencing (NGS)
The success rate of NGS for TBLC samples was 100% (26/26). Of the 26 patients who underwent NGS, 18 cases had a tumor cell count of 500 or more, and 8 cases had a cell count of less than 500. The median tumor nuclei content in all TBLC cases was 50% (10-90%). Tumor nuclei content was less than 30% and 20% in 6 (6%) and 3 (3%) cases, respectively.