The IASLC lung cancer staging project proposal for the classification of lung cancers with multiple pulmonary sites of involvement: the first step toward finding optimal treatment

Assessment of multifocal lung tumors and the distinction of synchronous primary tumors from intrapulmonary metastases represent an important problem as this decision significantly influences tumor staging and subsequent treatment strategies. Up to 8% of lung cancer patients present with two or more anatomically separate nodules. Yet, significant variability currently exists in treatments for these patients (1-4). Reasons for such ambiguity are that these patients represent a heterogeneous group of cohorts with marked difference in biological behaviors, survival, and recurrence pattern. Currently, no formal consensuses exist among clinicians in terms of staging, treatments, and follow-up.