Long-Term Survival of American Joint Committee on Cancer 8th Edition Staging Descriptors for Clinical M1a Non-Small Cell Lung Cancer.

BACKGROUND: The American Joint Committee on Cancer (AJCC) 8th edition TNM staging manual for non-small cell lung cancer (NSCLC) M1a descriptors includes tumors presenting with malignant pleural or pericardial effusion (ie, M1a-Effusion), pleural or pericardial nodule(s) (ie, M1a-Pleural), or separate tumor nodule(s) in a contralateral lobe (ie, M1a-Contralateral). RESEARCH QUESTION: Is M1a NSCLC presenting with malignant pleural or pericardial effusion associated with worse survival compared with other types of M1a NSCLC? STUDY DESIGN AND METHODS: Patients with cT1-4, N0-3, M1a NSCLC (satisfying a single M1a descriptor of M1a-Effusion, M1a-Pleural, or M1a-Contralateral), according to AJCC eighth edition staging criteria, in the National Cancer Database from 2010 to 2015 were included. Overall survival was evaluated by using Kaplan-Meier analysis, multivariable-adjusted Cox proportional hazards modeling, and propensity score matching. RESULTS: Of the 25,716 patients who met study eligibility criteria, 12,756 (49.6%) presented with M1a-Effusion tumors, 3,589 (14.0%) with M1a-Pleural tumors, and 9,371 (36.4%) with M1a-Contralateral tumors. In multivariable-adjusted analysis, compared to M1a-Effusion tumors, both M1a-Pleural tumors (hazard ratio, 0.68; 95% CI, 0.64-0.71; P < .001) and M1a-Contralateral tumors (hazard ratio, 0.66; 95% CI, 0.64-0.69; P < .001) were associated with better overall survival. No significant differences were found in overall survival between patients with M1a-Pleural tumors vs M1a-Contralateral tumors. In a propensity score-matched analysis of 5,581 patients with M1a-Effusion tumors and 5,581 patients with other M1a tumors (ie, M1a-Contralateral or M1a-Effusion), those with M1a-Effusion tumors had worse 5-year overall survival than patients with other M1a tumors (M1a-Effusion 6.4% [95% CI, 5.7-7.1] vs M1a-Other 10.6% [95% CI, 9.7-11.5]; P < .001). INTERPRETATION: In this national analysis of AJCC 8th edition cT1-4, N0-3, M1a NSCLC, tumors with malignant pleural or pericardial effusion were associated with worse overall survival than tumors with either pleural or contralateral pulmonary nodules. These findings may be taken into consideration for the upcoming ninth edition of the AJCC lung cancer staging guidelines.