**5. Conclusions**

In cases of multiple lung cancers, identifying the differences in the mutation profiles of multiple tumors will help determine their clonal origin and enable a distinction to be drawn between primary and metastatic tumors with great specificity, even in cases in which pathological distinction is impossible or equivocal. In addition, performing genetic diagnosis in addition to pathological diagnosis can help obtain a more accurate understanding of the pathology of multiple lung cancers and the lymphatic metastases. This approach may lead to the provision of treatment specifically tailored to the features of individual cases.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2077-0383/9/2/573/s1, Table S1: The genes targeted in the cancer panel, Table S2: Patient characteristics, Table S3: Mutation data in each cancer sample.

**Author Contributions:** T.G., Y.H., R.H. and T.N. wrote the manuscript. T.G., T.N., D.S., R.H., S.O. and Y.Y. performed the surgery. T.O., D.S. and R.H. carried out the pathological examination. Y.H., K.A., T.G., T.N., Y.Y., H.M., R.H., S.O. and M.O. participated in the genomic analyses. M.O. and Y.H. edited the final manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by a Grant-in-Aid for Genome Research Project from Yamanashi Prefecture (to Y.H. and M.O.) and by grants from Japanese Foundation for Multidisciplinary Treatment of Cancer (to T.G.).

**Acknowledgments:** The authors greatly appreciate Hidetoshi Shigetomo, Yumi Kubota, Ritsuko Yokouchi, Yumiko Kakizaki, Toshiharu Tsutsui and Yoshihiro Miyashita for helpful scientific discussion.

**Conflicts of Interest:** The authors declare no conflict of interest.
