The additional radiotherapy to adjuvant chemotherapy improves the prognosis of stage III-N2 with highest mediastinal lymph node metastasis in non-small cell lung cancer

Introduction The benefits of adjuvant chemoradiation therapy (CRT) for heterogeneous pathological N2 (pN2) diseases remain unclear in non-small cell lung cancer (NSCLC). This study aimed to investigate suitable pN2 patients for adjuvant CRT. Material and methods This study retrospectively reviewed the data of patients with pN2 NSCLC in Shanghai Pulmonary Hospital from January 2012 to December 2016. Included cases were subdivided as highest mediastinal lymph node (HM) ( n = 732) metastasis and non-HM metastasis ( n = 677) groups according to the International Association for the Study of Lung Cancer (IASLC). Furthermore, the Kaplan–Meier and Cox models were used to evaluate the prognostic benefits of adjuvant CRT in heterogeneous pN2 subgroups. Results A total of 1409 patients were enrolled in this study, with a median follow-up time of 63.8 months. Patients with HM involvement had worse prognoses ( p < 0.001 for recurrence-free survival (RFS) and overall survival (OS)). Furthermore, the survival improvement of adjuvant CRT was significant for these patients ( p < 0.001 for RFS and p = 0.032 for OS), regardless of whether it was single ( p < 0.001 for RFS and p = 0.029 for OS) or multiple pN2 ( p < 0.001 for RFS and p = 0.026 for OS) diseases. According to multivariable cox analysis, the long-term RFS and OS in the cancerous HM group were independently predicted by pathological N stage ( p = 0.002 for RFS and p < 0.001 for OS) and adjuvant CRT ( p < 0.001 for RFS and p = 0.011 for OS). Conclusion Metastatic HM was associated with a worse prognosis in pN2 disease. Our analysis supported that adjuvant CRT significantly improved both RFS and OS for these patients.