Targeted next-generation sequencing as a diagnostic tool in gastrointestinal system cancer/polyposis

Background: Recent advances in next-generation sequencing (NGS) technology have enabled multigene testing and changed the diagnostic approach to hereditary gastrointestinal cancer/polyposis syndromes. The aim of this study was to analyze different cancer predisposition genes in hereditary/sporadic gastrointestinal cancer/polyposis. Methods: Cancer predisposition genes were analyzed with an Illumina MiSeq NGS system in 80 patients with gastrointestinal cancer/polyposis who were examined between the years 2016 and 2019. Deletion/duplication analysis of MLH1, MSH2, and EPCAM genes was performed by using the multiplex ligation-dependent probe amplification method. Results: Germline testing of hereditary cancer-related genes was performed in 80 patients with gastrointestinal cancer/polyposis. A total of 30 variants in 30 cases (37.5%) were assessed as pathogenic/likely pathogenic. A total of 19 heterozygous variants were assessed as variants of uncertain clinical significance in 17 cases (21.25%) and 18 (22.5%) novel variations (9 pathogenic/likely pathogenic, 9 variants of uncertain significance) were determined. In 4 (5%) cases, multiplex ligation-dependent probe amplification detected deletions in MLH1, MSH2, and EPCAM genes. Conclusion: The accumulation of analyses with multigene testing will increase the available data for cancer predisposition genes in hereditary gastrointestinal cancer/polyposis. Educational campaigns for prevention, efficient screening programs, and more personalized care based on the profile of individual patients are necessary.