Molecular diagnostic characteristics based on the next generation sequencing in lung cancer and its relationship with...

Next generation sequencing (NGS) is a massively parallel sequencing technique that can be used to detect many forms of DNA variation, including point mutations, small fragment insertion deletions, gene recombination, and copy number variations. It can simultaneously analyze multiple genes and mutations, quantitatively detect gene mutation rate, and provide comprehensive information for clinicians. More and more lung cancer patients have benefited from studies on programmed death-1igand l (PD-L1) and immunocheckpoint inhibitors. The relationship between gene mutation and PD-L1 is also a focus of current research. Therefore, we collected a large number of cases to describe the molecular diagnostic characteristics of NGS in lung cancer and the relationship between NGS and PD-L1 expression.

A total of 1017 lung cancer patients with 15-gene panel (EGFR, ALK, ROS1, BRAF, MET, RET, ERBB2, KRAS, PIK3CA, KIT, ESR1, PDGFRA, DDR2, HRAS, NRAS) examined by NGS from our hospital were collected to analyze their clinicopathological characteristics. 600 of 1017 patients were tested for PD-L1 (22C3) by immunohistochemistry (IHC) at the same time. PD-L1 tumor proportion score (TPS) were used for comparative analysis with gene mutation results, and then to screen for possible correlation genes.

74.63 % (759/1017) of lung cancer patients had at least one version of the genes. The top three mutation were EGFR (46.41 %), KRAS (13.86 %) and PIK3CA (10.03 %). Mutations in EGFR, KRAS, PIK3CA, KIT, ESR1 and NRAS were associated with sex (P < 0.05). Except for EGFR, which was more frequent in female, other genes were more frequent in male. ALK was more detectable in patients younger than 60, while PIK3CA was more detectable in patients older than 60(P < 0.05). EGFR, ALK, ROS1, KRAS, PIK3CA, ESR1 and NRAS were associated with smoking (P < 0.05). EGFR, KRAS, PIK3CA and ESR1 were correlated with pathological histology (P < 0.05). Among the 15 genes, only EGFR was associated with pathological histology of invasive adenocarcinoma (IA). EGFR had the highest mutation rate (60.00 %) in Lepidic predominate IA. Significantly different in sample types were found in EGFR, ALK, MET, KRAS, PIK3CA and NRAS examined by NGS. There were significant differences in the TPS of PD-L1 (22C3) in EGFR, ALK, BRAF and MET variants (P < 0.05). EGFR mutations were more common in TPS < 1 %, ALK mutations were more common in TPS (1 %-49 %), and BRAF and MET mutations were more common in TPS ≥ 50 %.

In the 15-gene panel, in addition to EGFR, ALK and ROS1, MET, KRAS, PIK3CA, KIT, ESR1 and NRAS also had their own characteristics in sex, age, smoking history, histopathology, sample type and PD-L1, showing different clinicopathological tendencies. Understanding this information can help us optimize stratified lung cancer patients. Furthermore, it provides patients with a variety of diagnostic needs and a large number of unique clinical data worthy of clinical recognition.