Comprehensive profiling of the molecular characteristics of both primary tumor and local metastases tumor in Chinese lung cancers.

Abstract

e20517 Background: Metastasis tumor is the leading cause of lung cancer-related deaths, including local metastasis and distant metastasis. Despite its crucial clinical significance, local metastasis of lung cancer is still largely uncharacterized in terms of underlying molecular mechanisms. Here, we performed TSO500 (Illumina, San Diego, CA, USA) sequencing with 19 matched lung cancer primary and local metastatic samples to comprehensively profiling of lung cancer molecular characteristics. Methods: 19 lung cancer patients with paired primary tumor and local metastatic samples were enrolled, including 16 matched primary-lymph node samples and 3 primary-pleura samples. We compared molecular characteristics, including SNV and TMB, of matched samples. Molecular alterations identified were classified into shared (mutations in both primary and metastases) and private (mutations only in primary or metastases) groups. Thus, share mutation statistical analysis, pathway level enrichment and mutational signature was also done. Results: Comprehensively analysis of matched samples showed that mutational concordance between primary tumor and local metastases is lower. The average rate of concordance of primary-lymph node and primary-pleura was 40.6%±28.4%, 39.0%±33.9% respectively. Obviously, no difference in TMB between local metastases and primary tumor was found, average of primary vs lymph node and primary vs pleura was 7.5 vs 6.5, 6.9 vs 4.2 respectively. Significantly, we found that smoking lung cancer patients have higher TMB compared to non-smokers(p < 0.01), regardless primary tumor or metastatic lymph nodes. Conclusions: Lung cancer has higher inter-tumor heterogeneity with proportion of shared mutations less than 50%. Meanwhile, smoking lung cancer has higher TMB in both primary tumor and metastatic lymph nodes compared to non-smokers.