Nodal size ranking as a predictor of mediastinal involvement in clinical early-stage non-small cell lung cancer

In non-small cell lung cancer (NSCLC) patients, the recommended minimum requirement for an endoscopy-based mediastinal staging procedure is sampling the largest lymph node (LN) in right and left inferior paratracheal, and subcarinal stations. We aimed to analyze the percentage of cases where the largest LN in each mediastinal station was malignant in a cohort of NSCLC patients with mediastinal metastases diagnosed in the lymphadenectomy specimen. Furthermore, we investigated the sensitivity of a preoperative staging procedure in a hypothetical scenario where only the largest LN of each station would have been sampled. Prospective data of patients with mediastinal nodal metastases diagnosed in the lymphadenectomy specimens were retrospectively analyzed. The long-axis diameter of the maximal cut surface of all LNs was measured on hematoxylin and eosin-stained sections. Seven hundred seventy five patients underwent operation and 49 (6%) with mediastinal nodal disease were included. A total of 713 LNs were resected and 119 were involved. Sixty seven nodal stations revealed malignant LNs: in these, the largest LN was malignant in 39 (58%). In a “per patient” analysis, a preoperative staging procedure that sampled only the largest LN would have attained a sensitivity of 0.67; and if the largest and the second largest were sampled, sensitivity would be 0.87. In patients with NSCLC, nodal size ranking is not reliable enough to predict malignancy. In clinical practice, regardless of the preoperative staging method, systematic thorough sampling of all visible LNs is to be recommended over selective random samplings.