Prognostic significance of the 8th edition of the TNM classification for patients with extensive disease small cell lung cancer

Abstract

BackgroundSmall cell lung cancer (SCLC) is typically categorized according to disease extent as limited or extensive, and utility of the 8th TNM classification, recommended for lung cancer staging, which demonstrates a strong association with non-small-cell lung cancer (NSCLC) management, remains unclear.MethodsThis retrospective study included 277 consecutive SCLC patients treated at a single institution between 2008 and 2016.ResultsAccording to the currently used two-stage system, 186 (65.7%) of the patients were classified as having extensive disease (ED)-SCLC. Among the ED-SCLC patients, ten (5.3%), 38 (20.4%), 32 (17.2%), and 106 (57.0%) were categorized into stages M0, M1a, M1b, and M1c, respectively, according to the 8th TNM classification. There was a significant difference in overall survival based on the M descriptors: 15.8 (95% CI 9.4–22.2) months in the M1b group vs 7.3 (95% CI 5.7–8.9) months in the M1c group (P<0.001). Multivariate analysis showed that in addition to the known prognostic factors such as performance status, serum albumin, and lactate dehydrogenase, M descriptor was a prognostic factor (HR 1.95, 95% CI 1.38–2.77; P<0.001).ConclusionThe 8th TNM classification has a prognostic value in SCLC. Similarly to NSCLC, treatment approaches should be considered on the basis of the 8th TNM classification, especially stage IVA separate from stage IVB in ED-SCLC patients.