Separate or intrapulmonary metastasis?

Multiple primary lung cancers (MPLCs) appear to be increasing in global frequency. This may be a result of improvements in the resolution of cross-sectional imaging technology, as well as increased rates of low-dose chest computed-tomography screening programs. The incidence of MPLCs among patients with non-small cell lung cancer varies from 0.2% to 20% (1). Diagnosis and management of MPLCs remains controversial, as criteria for identifying MPLCs have been proposed and standardized for years (2,3), we still lack reliable and robust means of clearly discriminating patients with MPLCs from those with intrapulmonary foci of metastatic disease.