The clinical characteristics of total of 536 lung cancer patients are shown in . Of the 536 patients, 110 patients underwent surgical resection. Mean age was 64 yr (range: 29-85 yr), and 415 patients (77.4%) were male. Of these patients, 245 patients were diagnosed with adenocarcinoma (45.7%), 143 patients with squamous cell carcinoma (26.7%), 109 patients with small cell carcinoma (20.3%), 35 patients with other forms of non-small cell lung cancer (6.5%), and 4 patients with a combination of small cell carcinoma/non-small cell lung cancer (0.7%). BAF was observed in 55 patients (10.3%).
Clinical characteristics of patients (n = 536)
The characteristics of total 790 LNs are shown in . Malignant LN or reactive LN in EBUS-TBNA was defined according to the pathologic findings of biopsy or aspiration tissue. Of them, 527 LNs were malignant (66.7%) and 263 LNs were reactive (33.3%). Among the 263 reactive LNs, 69 LNs were resected by surgery and 92.8% of resected LNs were confirmed as reactive. The most frequently examined LN included 4R (30.3%), 7 (29.9%), and 4L (13.0%). The mean size of LN was 18.1 ± 10.0 mm and mean SUV was 6.6 ± 4.9. Pigmentation of EBUS-TBNA tissue was observed in 228 patients (28.9%) and BAF was observed in 92 LNs (11.6%) during bronchoscopy.
Characteristics of lymph nodes (n = 790)
The comparison of LN characteristics between malignant LN and reactive LN is shown in . The mean SUV of the malignant LN group was 8.1 ± 5.2, and the mean SUV of the reactive LN group was 3.7 ± 2.6 (mean difference: 4.4; P < 0.001). The mean size of the malignant LN group was 20.7 ± 10.2 mm, and the mean size of the reactive LN group was 12.9 ± 7.3 mm (mean difference: 7.9 mm; P < 0.001). Pigmentation of EBUS-TBNA tissue was observed in 14.4% of malignant LNs, which was significantly lower than that of reactive LNs, 57.8%. BAF was also observed less frequently in malignant LNs than in reactive LNs, 5.3% and 24.3%, respectively. More detailed analyses according to tissue type of primary lung cancer, BAF in malignant LNs or reactive LNs are shown in -.
Comparison of LN characteristics between malignant LN and reactive LN
Comparison of LN characteristics between tissue type of primary lung cancer
Comparison of LN characteristics between BAF positive or negative in reactive LN
The relative risks for developing malignant LN were 3.3 (95% confidence interval [CI], 2.1-5.1; P < 0.001) for LN ≥ 1 cm in size, 1.8 (95% CI, 1.5-2.3; P < 0.001) for SUV ≥ 2.5, 0.4 (95% CI, 0.3-0.6; P < 0.001) for macroscopic tissue pigmentation, and 0.4 (95% CI, 0.3-0.6; P < 0.001) for BAF. There was no significant difference in terms of sex.
The adjusted odds ratio for malignant LN was 0.46 (95% CI, 0.26-0.81; P < 0.001) for BAF, and 0.22 (95% CI, 0.15-0.33; P < 0.001) for pigmentation of EBUS-TBNA tissue () after adjusting an age, tissue type (NSCLC in contrast to SCLC), LN size (≥10 mm), and SUV (≥2.5). The specificities of pigmentation of EBUS-TBNA tissue and BAF for predicting a malignant LN were 42.2% and 75.7%, respectively, which was higher than the specificities of LN size ≥10 mm or SUV ≥2.5 ().
Logistic regression of parameters associated with malignant LNs (n = 720)
Diagnostic value of predicting malignant LNs