No existing pathologic or molecular test is currently capable of making the distinction between multiple independent lung primaries from metastatic disease with accuracy. The recent release of preliminary data from the NLST screening trial, suggesting survival benefit for screening high risk patients with CT scanning, will only increase the number of patients facing these treatment dilemmas. The research team has recently developed a test that allows this distinction with great accuracy. This test allows determination of lineage between two tumors using the identification of large genomic rearrangements using mate pair next generation sequencing (MP). The test has been developed using fresh frozen tissue from resected lung tumors and is currently being validated for a clinical test.