Surgical treatment of synchronous multiple primary lung cancers: a retrospective analysis of 122 patients.

Background: Synchronous multiple primary lung cancers (SMPLC) become more common in clinical practice. To identify factors attributed to SMPLC treatment outcomes, we have reviewed our experiences with surgical resections of SMPLC and analyzed the treatment outcomes in this paper. Methods: We retrospectively analyzed clinical characteristics and treatment outcomes of patients who have been diagnosed as SMPLC and underwent surgical resection between 1990 and 2010. Based on EGFR and KRAS mutations, we identified 27 cases as SMPLC out of 50 cases, which were difficult to distinguish primary lung cancers from metastases. A total of 265 tumors from 122 patients were studied. Results: The 5-year survival rate for all patients was 40.5%. There was a significant difference in the 5-year survival between smokers and never-smokers (30.8% vs. 55.6%, P=0.011). Survival rate was also different between patients with same tumor histology and those with different tumor histology (46.9% vs. 24.8%, P=0.036). In addition, Solid nodule and pneumonectomy were associated with the worse survival (P=0.026, P=0.030). Multivariable analysis identified smoking status, stage, lymph node metastasis and pneumonectomy as significant independent predictive factors for overall survival. Conclusions: Surgical treatment is a safe approach for patients with SMPLC; pneumonectomy should be avoided as far as possible given the poor prognosis. Mutational status of EGFR and KRAS may be advocated as a diagnostic criteria of synchronous lung cancer rather metastasis mainly in case of adenocarcinoma histology.