Effects of primary tumor resection on the survival of patients with stage IV extrathoracic metastatic non-small cell lung cancer: A population-based study

Background: Selected non-small cell lung cancer (NSCLC) patients with extrathoracic metastases might benefit from surgical intervention; however, the evidence is limited. We investigated the benefit of surgery in these patients regarding the extent of the metastatic disease.

Methods: Patients with extrathoracic metastatic NSCLC were identified in the US National Cancer Institute Surveillance, Epidemiology, and End Results database (2010-2015). Survival was compared before and after matching. Multivariate Cox regression models were built to identify factors associated with survival and to adjust for covariates in subgroup analysis.

Results: Of the 39,655 patients, 1206 underwent primary tumor resection, and 630 patients were identified 1:1 in surgical and nonsurgical groups after matching. In the entire cohort, patients who underwent surgery had significant prolonged overall survival (OS) in both unmatched (median survival time, [MST]: 14 vs. 6 months, p < 0.001) and matched (MST: 11 vs. 7 months, p < 0.001) cohorts. In the highly selected surgery-recommended cohort, surgical group still had a significantly longer OS (MST: 14 vs. 6 months, p < 0.001). Multivariate regression showed that surgery was independently associated with improved OS and lung cancer-specific mortality (LCSM) (OS: hazard ratio [HR]: 0.60, 95% confidence interval [CI]: 0.56-0.64, p < 0.001; LCSM: subhazard ratio [SHR]: 0.61, 95% CI: 0.57-0.66, p < 0.001). Subgroup analysis showed that surgery was an independent favorable predictor to survival in all cohorts except patients with N3 disease, and patients with single-organ metastasis were associated with the most prominent survival benefit from surgery.

Conclusions: Primary tumor resection was associated with improved survival in extrathoracic metastatic NSCLC patients, particularly for those with single-organ metastasis.