P3.12-16 Prognostic Impact of M Descriptors of the 8th Edition of TNM Classification for Extensive Disease-Small Cell Lung Cancer

Abstract

The International Association for the Study of Lung Cancer proposed the eighth edition of TNM classification of lung cancer on the basis of a new database in 2015. One of the most significant change in new criteria was that M descriptors has changed from three (M0, M1a and M1b) to four (M0, M1a, M1b and M1c). Although the 8th TNM classification is strong in the related with non-small cell lung cancer (non-SCLC) management, association between the 8th TNM classification and prognosis of SCLC patients remains unclear. In this study, we evaluated the applicability of the 8th TNM staging system to SCLC patients, especially whether prognosis of extensive disease (ED)-SCLC was related to the M descriptors. We performed a retrospective study of consecutive 277 SCLC patients who had treated at our hospital between January 2008 and December 2016. The SCLC patients classified based on the 8th TNM classification and evaluated clinical factors and survival. 186 (65.7%) of 277 SCLC patients were classified ED-SCLC based on the two-stage system, classically. Among the ED-SCLC patients, 10 (5.3%), 38 (20.4%), 32 (17.2%) and 106 (57.0%) were categorized into stage M0, M1a, M1b and M1c based on the 8th TNM classification, respectively. All ED-SCLC patients received systemic chemotherapy and median overall survival (OS) was 13.7 months. There were significant differences in OS [7.3 months; 95% confidence interval (CI), 5.7–8.9 months vs. 16.0 months; 95% CI, 13.2–18.8 months; p<0.001] according to the M descriptors (M0, M1a, M1b vs. M1c) and the TNM stage groups (III and IVa vs. IVb). Multivariate survival analyses showed that the M descriptor was one of prognostic factors (hazard ratio 1.50; 95% CI, 1.26–1.78 months; p<0.001) in addition to known prognostic factors such as ECOG performance status and pretreatment serum level of LDH. In this study, the 8th TNM classification had prognostic value in the SCLC patients treated with systemic chemotherapy. We suggested that ED-SCLC patients was divided into two subgroups based on the TNM classification. In ED-SCLC as well as non-SCLC, treatment development should be considered based on the TNM classification.