Hilar Lymphadenectomy Is Associated With Improved Disease-Free Survival in Pathologically N0 Non-Small Cell Lung Cancer.

[BACKGROUND] Aim of this study is to evaluate the prognostic role of nodal parameter in early stage pathologically patients with N0 who underwent lobectomy and lymphadenectomy.

[METHODS] Clinical and pathological characteristics of patients who underwent anatomical lung resection from 1/01/2010 to 31/12/2019 were reviewed and retrospectively analyzed. GGO and part-solid tumors, MIA, AIS, more than 5 cm in size, with nodal and/or distant metastases, or receiving neoadjuvant treatment were excluded. Operatory and pathological report were reviewed to collect data on lymphadenectomy. The primary end-point was disease-free survival (DFS), calculated from surgery to recurrence appearance. Clinical/pathological characteristics and nodal parameters were associate to DFS using Kaplan-Meier curves. The log-rank test was used to assess differences between subgroups. A multivariable model was built using Cox-regression analysis, including variable resulting significant (p value < 0.05), at univariable analysis.

[RESULTS] The final analysis was conducted on 487 patients. Most patients presented stage I tumor (82.4%). The mean number of resected nodes (#RN), resected N1 (#RN1) nodes, and resected N2 nodes (#RN2) resulted 9.5 ± 8.0, 3.4 ± 4.3, and 5.9 ± 4.4. The mean number of total resected stations (#RS), N1 resected stations (#RSN1), and N2 resected stations (#RSN2) resulted 2.5 ± 1.6, 1 ± 0.8, and 1.5 ± 1.2, respectively. During a mean follow-up of 43 ± 28 months, a recurrence occurred in 137 (28.1%) patients. At univariable analysis, age < 70 years (p = 0.025), N1 lymphadenectomy (p = 0.019), #RSN1 ≥ 3 (p = 0.001), #RN ≥ 10 (p = 0.019), #RN1 ≥ 3 (p < 0.001), node sampling with more than 3 resected nodes (p = 0.049), at least 3 stations with 3 N1 nodes resected (p = 0.013), at least 3 stations resected with 10 lymphnodes, and 3N1 lymphnodes (p = 0.020) significantly correlated with improved DFS. Multivariable analysis confirmed as independent prognostic factor #RN1 ≥ 3 (p = 0.017; HR 1.782; and 95% CI: 1.107-2.867). Patients with #RN1 ≥ 3 presented a 5-years DFS of 76.3% versus 57.8% of patients with #RN1 < 3 (p = 0.001).

[CONCLUSIONS] Hilar lymphadenectomy seems to significantly correlate with disease-free survival in patients with pN0NSCLC and should be better defined in lymphadenectomy guidelines.