Consolidation/Tumor Ratio on Chest Computed Tomography as Predictor of Postoperative Nodal Upstaging in Clinical T1N0 Lung Cancer.

BACKGROUND: In clinical T1N0 peripheral lung cancers, lymph node upstaging is occasionally encountered postoperatively. However, nodal upstaging is rare in lung cancers presenting as ground-glass opacities. The aim of this study was to determine if lymph node upstaging could be reliably extrapolated from parameters such the consolidation/tumor ratio of chest computed tomography.

METHODS: We conducted a retrospective study of 486 patients treated for peripheral clinical T1N0 non-small cell lung cancer, each undergoing lobectomy with mediastinal lymph node dissection. We compared preoperative variables in the pathologic N0 and nodal upstaging groups, analyzing such variables to determine factors predictive of lymph node upstaging.

RESULTS: Of the 486 patients studied, lymph node upstaging occurred in 42 (8.6%). In the upstaging group, the mean nodule diameter exceeded that of the pathologic N0 group (2.3 vs 1.9 cm, respectively; p < 0.001), and the mean consolidation/tumor ratio was larger in the upstaging group than the pN0 group (0.95 vs 0.68, respectively; p < 0.001). Nodule diameter and consolidation/tumor ratio emerged as significant predictive factors for lymph node upstaging after surgery in a multivariate analysis (hazard ratio [HR] 2.259, p = 0.039; HR 173.645, p = 0.001, respectively).

CONCLUSIONS: Consolidation/tumor ratio and nodule diameter are significant predictive factors of postoperative lymph node upstaging. The higher the consolidation/tumor ratio and smaller the nodule diameter, the less likely the occurrence of postoperative lymph upstaging would be in clinical T1N0 peripheral non-small cell lung cancer.