Clinical Validation of the Canada Lymph Node Score for Endobronchial Ultrasound

BACKGROUND: The Canada Lymph Node Score (CLNS) uses 4 sonographic criteria to predict the risk of malignancy in lymph nodes during endobronchial ultrasound. The CLNS may play a role in identifying targets for biopsy or rebiopsy during invasive mediastinal staging for lung cancer. However the CLNS has not yet been prospectively validated in routine clinical practice. METHODS: CLNSs for each lymph node biopsied during endobronchial ultrasound were prospectively captured for 1 year (2019). The CLNS and the presence of malignancy in each node were compared. Univariate binary logistic regression was completed for each ultrasonographic feature and multivariate logistic regression model. RESULTS: CLNSs and diagnostic pathology results were available for 367 lymph nodes. Incidence of malignancy increased with higher scores. Scores ≥ 3 were significantly associated with malignancy (specificity, 84.4%; positive likelihood ratio, 4.0). Area under the curve was 0.76, indicating a good ability of the model to predict presence or absence of malignancy. Nodes scoring < 2 and negative on computed tomography and positron emission tomography were malignant in 10.1%. CONCLUSIONS: The CLNS correlates with the presence or absence of malignancy in thoracic lymph nodes and may serve as an adjunct to currently available methods of invasive and noninvasive mediastinal staging. The CLNS may be most helpful in selecting which nondiagnostic lymph nodes require rebiopsy. There is a significant risk of a false-negative result even with a score of 0, and using a combination of low CLNSs and negative conventional radiology to obviate the need for any initial biopsy remains to be studied in prospective trials.