Importance of Lymph Node Evaluation in 2-cm Pure-Solid Non-Small Cell Lung Cancer

BACKGROUND The prevalence of lymph node (LN) metastasis in small-sized lung cancer varies depending on the tumor size and proportion of ground-glass opacity. We investigated occult LN metastasis and prognosis in patients with small-sized non-small cell lung cancer (NSCLC), mainly focusing on the pure-solid tumor. METHODS We retrospectively reviewed patients with 52-cm clinical N0 NSCLC who underwent lung resection with curative intent from 2003 to 2017. Among them we analyzed patients who also underwent adequate complete systematic LN dissection. Pathologic results and disease-free survival of the radiologically mixed ground-glass nodule (mGGN) and pure-solid nodule (PSN) groups were analyzed. RESULTS Of 1329 patients analyzed, 591 had mGGNs and PSNs. As tumor size increased, patients in the mGGN group showed no difference in LN metastasis: <= 1 cm, 2.27%; 1.0 to 1.5 cm, 2.19%; and 1.5 to 2.0 cm, 2.18% (P [ .999). However the PSN group showed a significant difference in LN metastasis as the tumor size increased: <= 1 cm, 2.67%; 1.0 to 1.5 cm, 12.46%; and 1.5 to 2.0 cm, 21.31% (P < .001). In the multivariate analysis tumor size was a significant predictor of nodal metastasis in the PSN group but not in the mGGN group. In terms of 5-year disease-free survival, the mGGN group showed a better prognosis than the PSN group (94.4% vs 71.2%, P < .001). CONCLUSIONS We need to conduct a thorough LN dissection during surgery for small-sized NSCLC, especially for pure-solid tumors >= 1 cm. (Ann Thorac Surg 2024;117:586-93) (c) 2024 by The Society of Thoracic Surgeons. Published by Elsevier Inc.