P1.03-069 EGFR Mutations Have Greater Influence on Survival Than Proposed M Descriptors of New TNM Classification for Lung Cancer

Abstract

The forthcoming 8th edition of TNM staging system for lung cancer proposes revision of M descriptor. No changes of M1a category is suggested, while further sub-classification of M1b category into M1b (single distant metastatic lesion in single organ) and M1c (multiple distant metastatic lesions) is proposed. The limitations of new classification due to lack of information on EGFR and ALK status that significantly impact treatment response and outcome have been pointed out, however no further analysis addressing this issue has been published. Here we report the impact of EGFR mutation status on survival in view of new TNM classification system. Database of 479 metastatic non-small cell lung cancer (NSCLC) patients, treated between 2009 and 2011, all tested for EGFR mutations, was retrospectively reviewed to categorize them into one of the new sub-groups according to new M descriptors. Medical records of 355 patients, among them 89 with EGFR mutations (EGFR-m), had sufficient information that allowed appropriate new categorization. After a median follow up of 53.9 months, median overall survival (mOS) of EGFR-m patients (20.6 months) was significantly longer than mOS of patients without EGFR mutations (8.3 months, p<0.001). Patients with the smallest disease burden (M1b sub-group) had the longest mOS among EGFR wild type patients (EGFR-wt) and EGFR-m patients, 14.4 months and 41.1 month, respectively. However, due to small number of patients in M1b subgroup, the difference was not statistically significant (p=0.08). In spite of widespread metastatic disease in M1c EGFR-m patients, they had longer mOS than M1b EGFR-wt patients with the lowest disease burden, 18.8 vs 14.4 months, respectively. EGFR mutational status has probably more important impact on mOS than the number of metastasis or number of metastatic sites in NSCLC. Our results indicate that further analysis is warranted to address this issue.Tabled 1M descriptorEGFR-mEGFR-wtnmOS (months)nmOS (months)pM1a1722.36110.70.022M1b541.13214.40.080M1c6718.81736.6<0.001all8920.62668.3<0.001 Open table in a new tab