Application of the new 8th TNM staging system for non-small cell lung cancer: treated with curative concurrent chemoradiotherapy

BACKGROUND The eighth tumor, node, metastasis (TNM) staging system (8-TNM) for non-small cell lung cancer (NSCLC) was newly released in 2015. This system had limitation because most patients included in the analysis were treated with surgery. Therefore, it might be difficult to reflect prognosis of patients treated with curative concurrent chemoradiotherapy (CCRT). Purpose of this study was to investigate clinical impact of the newly published 8-TNM compared to the current seventh TNM staging system (7-TNM) for locally advanced NSCLC patients treated with CCRT. METHODS New 8-TNM was applied to 64 patients with locally advanced NSCLC who were treated with CCRT from 2010 to 2015. Changes in T category and stage group by 8-TNM were recorded and patterns of change were evaluated. Survival was analyzed according to T category, N category, and stage group in each staging system, respectively. RESULTS Among the total of 64 patients, 38 (59.4%) patients showed change in T category while 22 (34.4%) patients showed change in stage group using 8-TNM compared to 7-TNM. Survival curves were significantly separated in the 8-TNM stage group (p = 0.001) than those in the 7-TNM (p > 0.05). Especially, survival of newly introduced stage IIIC by 8-TNM was significantly lower than that of others. On the other hand, there was no significant survival difference between T categories in each staging system. CONCLUSIONS Subdivision of stage III into IIIA, IIIB, and IIIC by 8-TNM for patients treated with CCRT better reflected prognosis than 7-TNM. However, subdivision of T category according to tumor size in 8-TNM might be less significant.