The clinical-histologic and prognostic characteristics in patients with a second primary non-small-cell lung cancer after a lobectomy

OBJECTIVES: The goal of this study was to investigate whether an operation can offer survival benefits for patients with a second primary non-small-cell lung cancer (NSCLC) after a lobectomy for a first primary NSCLC and to analyse the characteristics affecting the survival of those patients. METHODS: We performed survival analyses of patients with a second primary NSCLC based on the Surveillance, Epidemiology and End Results program and used propensity score matching to reduce the potential bias and analyse the data. In addition, the primary observational end point was overall survival (OS), and the secondary observational end point was histologic migration. RESULTS: The data from 944 patients were used to perform the main analysis. A total of 36.2% of patients experienced a shift in tumour histologic type between 2 diagnoses of primary NSCLC, and this shift significantly affected OS (P = 0.0065). The median survival time in patients with surgical resection and those without an operation was 52.0 months versus 33.0 months, respectively. Patients with surgical resection at the secondary diagnosis had better survival than those without surgery (5-year OS rate: 48.0% vs 34.0%, P < 0.001). In addition, compared with a pneumonectomy and a sublobar resection, a lobectomy was the optimal surgical procedure for patients diagnosed with a second primary NSCLC after adjusting for other confounders (adjusted hazard ratio: 0.68, P < 0.01). However, in the subgroup analysis, lobar and sublobar resections could provide similar survival benefits for patients with tumour size ≤20 mm (P = 0.5). CONCLUSIONS: The operation, especially a lobectomy, can prolong OS in patients with a second primary NSCLC. Besides, sublobar resection can be performed in selected patients with tumour size ≤20 mm. Moreover, histologic migration may impact the survival of those patients with a secondary primary NSCLC.