Endoscopic ultrasonography (EUS) is useful in determining mediastinal lymph node (LN) metastases in patients undergoing staging for lung cancer. However, fine needle aspiration (FNA) of LNs is often performed only if suspicious features are present. The utility of individual LN features in predicting malignant cytology remains unclear.
To evaluate the utility of EUS LN features for predicting malignant cytology.
Prospective observational study.
Two tertiary care centers in USA.
425 patients with primary lung cancer underwent EUS. All mediastinal LNs were described according to size, shape, echogenicity, and edge characteristics. FNA was performed on LNs with any features suggestive of malignancy. EUS-FNA cytology was classified as benign or abnormal (suspicious/malignant). The utility of LN features in predicting malignant cytology were determined and further analyzed by logistic regression and a predictive model was established.
EUS detected 836 LNs in 425 patients, and FNA was obtained in 698. On multivariable analysis, only round shape, short axis >8.3 mm, and sharp margins were predictive of malignant cytology. According to the predictive model, the calculated probability of having malignancy is less than 4% (95% CI 0.022-0.064) when none of the LN features are present, and 63% (95% CI, 0.517-0.722) when all features were seen.
No surgical histology as gold standard.
Among patients with lung cancer, EUS features of round shape, sharp margins and short axis > 8.3 mm are significant predictors of malignancy. The probability of malignancy is low when none of the features are present.