Histologic lung cancer subtype differentiates synchronous multiple primary lung adenocarcinomas from intrapulmonary metastases.

Background: Distinguishing synchronous multiple primary lung cancers (SMPLCs) from intrapulmonary metastases is important. The objective of this study was to determine long-term survival in patients who underwent surgical resection for synchronous multiple lung cancers and identify additional criteria that may be useful to distinguish patients with SMPLCs from those with more advanced disease.

Methods: The medical records of patients with lung cancer who underwent planned resection for synchronous multiple lung cancers from 2007 to 2012 at our institutions were reviewed retrospectively. A comprehensive histologic assessment was used to determine whether the tumors were metastases or separate synchronous primary tumors.

Results: A total of 51 patients with synchronous multiple lung cancers underwent surgical resection. Twenty-nine patients had ipsilateral synchronous multiple lung cancers, and 22 had bilateral synchronous multiple lung cancers. No perioperative death occurred. The survival analysis of all 51 patients with synchronous multiple lung cancers who underwent planned resection of all lesions showed 3- and 5-year overall survival rates of 86% and 67%, respectively, The median overall survival was not reached. The comprehensive histologic assessment identified six patients with intrapulmonary metastasis and 45 patients with SMPLCs. Intrapulmonary metastases were associated with decreased survival. Among patients with SMPLCs, the epidermal growth factor receptor mutation distribution shown high concordant frequency rate of 35% (5/14).

Conclusions: Survival after surgical resection of synchronous multiple lung cancers in different lobes was promising. A comprehensive histologic assessment was useful for differentiating SMPLCs from intrapulmonary metastases.