Pathological complete response after neoadjuvant/induction treatment: where is its place in the lung cancer staging system?

OBJECTIVES: Prognosis for patients with non-small-cell lung cancer (NSCLC) who, after neoadjuvant/induction and surgery, have a pathological complete response (pCR) is expected to be improved. However, the place of the pCR patients in the context of the tumour, lymph node and metastasis (TNM) staging system is still not defined. The aim of this study is to investigate the long-term survival of NSCLC patients with pCR and to find their appropriate staging category within the TNM staging system. METHODS: We retrospectively reviewed the prospectively recorded data of 1076 patients undergoing surgery (segmentectomy or more) for NSCLC between 1996 and 2016. Patients were divided into 2 groups. Group 1: clinical early-stage patients who underwent direct surgical resection (n = 660); group 2: patients who received neoadjuvant/induction treatment before surgical resection for locally advanced NSCLC (n = 416). Morbidity, mortality, survival rates and prognostic factors were analysed and compared. RESULTS: Postoperative histopathological evaluation revealed pCR in 72 (17%) patients in group 2. Overall 5-year survival was 58.7% (group 1 = 62.3%, group 2 = 52.8%, P = 0.001). Of note, 5-year survival was 72.2% for pCRs. In addition, 5-year survival for stage 1a disease was 82.6% in group 1 and 63.2% in group 2 ( P = 0.008); 70.3% in group 1 and 60.5% in group 2 for stage 1b (P = 0.08). Patients with stage II had a 5-year survival of 53.9% in group 1 and 51.1% in group 2 (P = 0.36). CONCLUSIONS: This study shows that patients with locally advanced NSCLC developing a pCR after neoadjuvant/induction treatment have the best long-term survival and survival similar that of to stage Ib patients.