ALK rearrangement is an independent predictive factor of unexpected nodal metastasis after surgery in early stage, clinical node negative lung adenocarcinoma

Objectives: Despite notable advances made in preoperative staging, unexpected nodal metastases after surgery are still significantly detected. Given the promising role of neoadjuvant targeted treatments, the definition of novel predictive factors of nodal metastases is an extremely important issue. In this study we aim to analyze the upstaging rate in patients with early stage NSCLC without evidence of nodal disease in the preoperative staging who underwent lobectomy and radical lymphadenectomy.

Material and methods: Patients who underwent lobectomy and systematic lymphadenectomy for early stage LUAD without evidence of nodal disease at the preoperative staging using NGS analysis for actionable molecular targets evaluation after surgery were evaluated. Exclusion criteria included the neoadjuvant treatment, incomplete resection and no adherence to preoperative guidelines.

Results: A total of 359 patients were included in the study. 172 patients were female, and the median age was 68 (61-72). The variables that showed a significant correlation with the upstaging rate at the univariate analysis were the ALK rearrangement, the number of resected lymph nodes and the diameter of the tumor. This result was confirmed in the multivariate analysis, with an OR of 8.052 (CI95% 3.123-20.763, p = 0.00001) for ALK rearrangement, 1.087 (CI95% 1.048-1.127, p = 0.00001) for the number of resected nodes and 1.817 (CI95% 1.214-2.719, p = 0.004) for cT status.

Conclusion: Our results showed that in a homogeneous cohort of patients with clinical node early stage LUAD the ALK rearrangement, the number of resected lymph nodes and the tumor diameter can significantly predict nodal metastasis.