Characterization Of Heterogeneity In Three Lung Cancer Patients With Multiple Nodules By Whole Exome Sequencing.

e21530 Background: Tumor heterogeneity is an important characteristic of malignant tumors that reflects the high complexity and diversity in the process of evolution. It can lead to differences in tumor growth rate, invasion, metastasis, drug sensitivity and prognosis. At present, there exist few genome-wide studies on heterogeneous cases of multiple nodules for patients with non-small-cell lung cancer (NSCLC). Methods: In this study, we performed genetic profiling using a combination of targeted panel and whole exon genome sequencing (WES) on all lesions of three NSCLC patients with multiple nodules. Results: Driver gene alterations were detected in all lesion samples of the three patients. One patient presented with three nodules, which harbored EGFR L858R, ERBB2 exon 20 insertion and a EML4-ALK fusion. Evolutionary analysis showed strong heterogeneity among the three lesions. The three lesions of patient 2 showed EGFR L858R in two lesions (2A and 2C), and a ERBB2 exon 20 insertions in the other (2B). Mutational signatures and cluster analysis of somatic mutations also showed commonality between sample 2A and 2C, suggesting that they might arise from the same clone. Patient 3 had seven lesions. Analysis of somatic mutations and copy number variations revealed possible route of metastasis. Conclusions: Detailed analysis of genetic mutation characteristics and biological evolution trees showed that there were substantial heterogeneity and distinct evolutionary relationships among the different lesions of the same individual. Consequently, such information could aid in the determination of primary and metastasis of tumor lesions and guide the selection of treatment options.