| International Session（Symposium）3(JSGS・JSGE・JSH・JSGCS) |
| Fri. November 22nd 14:00 - 16:30 Room 11: Kobe International Exhibition Hall No.2 Building Hall (South) |
| Hypermutator in gastrointestinal and hepatopancreatobiliary cancers | |||
| Hiroyuki Matsubayashi1,2, Yoshimi Kiyozumi1, Masatoshi Kusuhara3 | |||
| 1Division of Genetic Medicine Promotion, Shizuoka Cancer Center, 2Division of Endoscopy, Shizuoka Cancer Center, 3Research Institute, Shizuoka Cancer Center | |||
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| [Background&Aim] Hypermutator (HM) is a cancer with numerous mutations, displaying neoantigens on the cell surface, and therefore responds well to immune-checkpoint inhibitors. This study aimed to clarify the incidences and characteristics of HM in the gastrointestinal and hepatopancreatobiliary (GI-HPB) cancers. [Methods] 1400 patients, who underwent surgical resection for their GI-HPB cancers, participated this study. DNA was extracted from the tumors and peripheral blood, and mutations were analyzed using next generation sequencer for 47 inherited cancer- and 411 cancer-associated genes. HM was defined when ≥20 mutations were detected per one Mb (tumor mutation burden: TMB). [Results] 1400 cancer cases included 827 colorectal cancers (CRCs), 282 gastric cancers (GCs), 107 hepatocellular carcinomas (HCCs), 5 small intestine cancers, etc. HM was detected in 91 (6.5%) total cases; i.e., 56 (6.8%) CRCs, 32 (11.3%) GCs, 2 (40%) small intestine cancers, and 1 (0.9%) HCCs. TMB of HM was significantly higher in CRCs than GCs (P=0.02), and especially high in CRCs with POLmutations (P<0.001). In CRCs, incidence of HM was different by location (right>left, P<0.001). HM of CRCs frequently showed BRAFmutation (57.1%) and POLmutation (21.4%). Pathogenic variants of germline mismatch repair genes were detected in 8 cases. [Conclusions] HM is recognized in about 10% of GI cancers. In HM of CRCs, mutations of BRAFand POLwere frequently recognized, and Lynch syndrome exists in some proportion. |
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Index Term 1: hypermutator Index Term 2: gastrointestinal cancer |
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