Fibrosis or necrosis in resected lymph node indicate metastasis before chemoradiotherapy in lung cancer patients

Background/Aim: The histological features of lymph nodes (LNs) treated by chemoradiotherapy (CRT) in non-small cell lung cancer (NSCLC) have not been well studied. The purpose of this study was to evaluate the histological findings of LNs affected by CRT. Patients and Methods: Among 107 clinically N2 NSCLC patients who underwent induction CRT followed by surgery from 1999 to 2017, 24 patients who received pathological evaluation of mediastinal LN before CRT were enrolled in this study. Postoperatively, we histologically reviewed all resected LNs (n=117) of the station evaluated before CRT. Results: Fibrosis and/or necrosis were observed in all investigated LN stations. Histological observation of fibrosis and/or necrosis in the resected LNs after CRT indicated the presence of LN metastasis before CRT. Conclusion: The metastatic LNs that responded to CRT showed specific histological features, which enabled us to know the accurate clinical stage of the patient even though cancer cells were not found in the post-treated LNs.