The association between clinical parameters and resectability in stage III non-small cell lung cancer, and a combination of N2 lymph node burden and lung immune prognostic index score as a potential biomarker

Background: Surgery is important treatment option for stage III non-small cell lung cancer (NSCLC) because of its curative potential. We investigated the characteristics of resectable patients, and compared the outcomes according to treatment modalities. Methods: Among 1,092 patients with NSCLC diagnosed between 2008 to 2020 from 7 university hospitals of Catholic Medical Center, we retrospectively analyzed 252 patients with clinical or pathological stage III. We compared survival outcomes among the groups according to resectability, first-line treatments, and the lung immune prognostic index (LIPI) score. Clinical N2 subgroup was analyzed using multi-parameter scoring system. Results: The resectable group consisted of less smokers, showed better pulmonary function and lower inflammatory markers, and tended to be diagnosed as earlier cancer stage than the unresectable group. The resectable group showed better progression-free survival (PFS) and overall survival (OS) than the unresectable group (P<0.001 and P<0.001, respectively). Regarding the first-line treatment, surgery showed the longest median PFS (33.70 months) and the highest 12-month OS rate (91.6%) than the other treatment modalities. OS was significantly different depending on the LIPI score in whole population, as well as in the unresectable group (P=0.004 and P=0.003, respectively). LIPI 0 group exhibited better OS than LIPI 1 and 2 in both populations. Eastern Cooperative Oncology Group (ECOG) 2-4, LIPI 1-2, and first-line treatment were independent prognostic factors for OS. Smoking, forced expiratory volume in the first second (FEV1) and more advanced cancer stage were associated with unresectability. In subgroup analysis of N2 disease, we attempted to create new scoring system combining lymph node (LN) status and LIPI score. This scoring system showed significant association with OS. Conclusions: The patients with resectable stage III NSCLC showed better PFS and OS than the patients with unresectable tumor. LIPI score exhibited possibility to be used as potential biomarker in stage III NSCLC. The multi-parameter scoring system using LN status and LIPI score was predictive of OS in the N2 subgroup.