Comparison of genetic profiles among primary lung tumor, metastatic lymph nodes and circulating tumor DNA in treatment-naïve advanced non-squamous non-small cell lung cancer patients

Abstract

ObjectivesGenetic profiles of primary and metastatic lung tumor have been investigated by previous studies. However, whether they can be replaced by each other to guide treatment remains controversial. Moreover, it is unclear that whether genetic profiles of plasma can reflect genetic divergence between primary and metastatic lesions. Materials and methodsIn this prospective study, we collected 35 pairs of matched primary tumor tissue, metastatic lymph nodes and plasma from treatment-naïve patients with advanced non-squamous non-small cell lung cancer (NSCLC) and applied to capture-based sequencing using a panel consisting 56 NSCLC-related genes to interrogate the heterogeneity and similarity among the 3 sites. ResultsWe observed 62.0% (67/108) by-variant concordance rate among primary tumor, metastatic lymph nodes and plasma as well as 76.4% (81/106) by-variant concordance rate between primary tumor and metastatic lymph nodes. When the analysis restricted to driver genes, we achieved 60.9% (28/46) and 77.3% (34/44) concordance, respectively. Furthermore, there is no statistically significant difference in progression-free survival (PFS) of 17 patients who used matched targeted therapy between patients having 100% concordance rate between primary tumor and metastatic lymph nodes and patients having partially matched mutational profiles. ConclusionCollectively, our study revealed a similar genetic profile shared between primary tumor and metastatic lymph nodes. The limited discordance observed can be partially reflected by plasma. Sequencing results obtained from either site can be utilized for providing treatment guidance.