Real-world status of multimodal treatment of Stage IIIA-N2 non-small cell lung cancer in Japan: Results from the SOLUTION study, a non-interventional, multicenter cohort study.

Objectives: There is limited consensus on resectability criteria for Stage IIIA-N2 non-small cell lung cancer (NSCLC). We examined the patient characteristics, N2 status, treatment decisions, and clinical outcomes according to the treatment modality for Stage IIIA-N2 NSCLC in Japan.

Materials And Methods: Patients with Stage IIIA-N2 NSCLC in Japan were consecutively registered in the SOLUTION study between 2013 and 2014. Patients were divided according to treatment (chemoradiotherapy [CRT], surgery + perioperative therapy [neoadjuvant and/or adjuvant therapy], surgery alone). Demographic characteristics, N2 status (number and morphological features), pathological information, and treatments were analyzed descriptively. Overall survival (OS), progression-free survival (PFS), and disease-free survival (DFS) were estimated using the Kaplan-Meier method.

Results: Of 227 patients registered, 133 underwent CRT, 56 underwent surgery + perioperative therapy, and 38 underwent surgery alone. The physicians reported the following reasons for unresectability for 116 of 133 CRT patients: large number of metastatic lymph nodes (70.7 %), extranodal infiltration (25.0 %), poor surgical tolerance (19.0 %), or other reasons (18.1 %). CRT was more frequently performed in patients whose lymph nodes had an infiltrative appearance (64.3 %) and was the predominant treatment in patients with multiple involved stations (discrete: 60.0 %; infiltrative: 80.4 %). Distant metastasis with/without local progression was found in 50.4 %, 50.0 %, and 36.8 % of patients in the CRT, surgery + perioperative therapy, and surgery alone groups, respectively. The respective 3-year OS and DFS/PFS rates (median values) were as follows: surgery + perioperative therapy-61.9 % (not reached) and 37.1 % (22.4 months; DFS); CRT group-42.2 % (31.9 months) and 26.8 % (12.0 months; PFS); surgery alone group-37.7 % (26.5 months) and 28.7 % (12.6 months; DFS).

Conclusion: This study has illuminated the real-world decision rules for choosing between surgical and non-surgical approaches in patients with Stage IIIA-N2 NSCLC. Our landmark data could support treatment decision making for using immune checkpoint inhibitors and targeted therapy for driver oncogenes in the perioperative therapy era.