Background Metastatic non-small cell lung cancer (mNSCLC) can present as de novo or relapsed disease. This study aimed to determine the clinical prognostic factors impacting post-metastatic survival, specifically comparing outcomes in de novo versus relapsed early stage populations.

Method Retrospective review of mNSCLC patients diagnosed between January 1999 and December 2013 in the Glans-Look Lung Cancer Database was conducted to identify relapsed early stage and de novo cases. Fisher's exact and Wilcoxon rank-sum tests were used to analyze categorical and continuous factors, respectively. Survival outcomes were analyzed and compared via the Kaplan-Meier and log-rank tests. Cox regressions were used to determine the impact of de novo versus relapsed mNSCLC presentation on prognosis, while adjusting for multiple confounders. We excluded stage III patients.

Result 3039 de novo and 185 relapsed patients were identified. Median post-metastatic survival was significantly longer for relapsed vs de novo, 8.90 (CI: 6.24-12.06) versus 3.71 (CI: 3.48-3.98) months, (p<0.001). Relapsed patients also demonstrated significant survival gains since 1999-2004. Different patterns of smoking history, histology, systemic anti-cancer therapy (SACT) usage and number of extra-pulmonary sites existed between the relapsed and de novo cohorts. Multivariate analysis demonstrated that de novo disease, male gender, ‘Never’ smoking history, ‘NOS’ histology, and the presence of extra-pulmonary metastases were significant factors in predicting a worse prognosis. SACT receipt and ‘Other’ histology were associated with better outcomes. In the relapsed subset, squamous cell histology also boded inferior survival. (Table 1)

Conclusion Relapsed and de novo patients represent significantly different sub-populations within mNSCLC, with survival favoring relapsed patients. This finding may inform discussions around prognosis, reinforce the value of follow-up/surveillance of early stage patients, and provide support for screening initiatives aimed at reducing the burden of de novo disease.

Keywords advanced NSCLC, de novo, relapsed