Local Control by Mediastinal Lymph-Node Dissection in Stage I Non-Small-Cell Lung Cancer

Mediastinal lymph-node dissection (MLND) is recommended for resectable non-small-cell lung cancer (NSCLC); however, its prognostic impact remains controversial. We evaluated whether MLND improves prognosis in patients with radiologically solid-dominant clinical stage I NSCLC.

We retrospectively reviewed 2212 patients who underwent lobectomy for solid-dominant clinical stage I NSCLC between 2010 and 2022. Prognosis and local control were compared between the MLND and non-MLND groups.

The MLND and non-MLND groups included 1912 and 300 patients, respectively. After propensity score matching, 5-year overall survival did not show a statistically significant difference between the groups (85.3% vs 79.3%, P = .089). MLND identified occult pN2 metastasis in 7.3% (138/1912) of patients. Notably, 3.6% (68/1912) of the entire MLND cohort had pN2 disease yet remained recurrence-free. Furthermore, the MLND group demonstrated significantly lower mediastinal lymph-node recurrence than the non-MLND group (P = .017). Among patients with pN2 disease in the MLND group, those with recurrence (n = 70) had a higher incidence of intrapulmonary metastases (P = .042), a higher number of mediastinal lymph-node metastases (P = .002), and a lower rate of skip-N2 involvement (P = .031).

Mediastinal lymph-node dissection provides superior local control by reducing mediastinal recurrences and enables accurate pathological staging. While this advantage guides appropriate adjuvant therapy selection, the direct impact of MLND on overall survival remains uncertain. Its true survival benefit should be evaluated in future prospective randomized trials.