or IHC . Next-generation sequencing ( NGS ) has emerged as a promising molecular diagnostic technique for clinical practice due to its accuracy in detecting most genomic alterations by allowing parallel sequencing in a single assay . 42 , 43 NGS is the blanket term used to describe a number of different second- and third- generation sequencing technologies , which are more efficient and show higher throughput than Sanger sequencing , a first-generation sequencing technology . Platforms for NGS from Illumina and Thermo Fisher are used widely . 44 NGS can be applied in the form of large-scale sequencing to detect genetic alterations such as gene mutation and amplification by sequencing the whole genome , exome or transcriptome . By contrast , NGS can also be applied in the form of targeted sequencing to detect and validate genome alterations related to cancer genes by performing deep sequencing on genomic regions of interest . 45
It has been acknowledged that molecular approaches improve the accuracy of ALK fusion detection , by resolving discordant or borderline cases . 46 – 48 However , one of the most valuable advantages of NGS should be attributed to its high negative predictive value compared with FISH testing . Ali et al reported that 35 % of ALKpositive cases detected by NGS were negative in ALK FISH , where only 20 of the 31 ALK-positive cases were concordant for ALK rearrangement and the remaining 11 cases were only NGS-positive . 49 Importantly , the majority of ALK NGS-positive , FISH-negative patients responded to crizotinib ,
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