Abstract：
A 47-year-old woman diagnosed with transverse colon cancer with liver, peritoneal, and lymph node metastases was admitted. Modified FOLFOX6(mFOLFOX6)regimen was given as a first line chemotherapy and was followed by pembrolizumab after 1 cycle of the mFOLFOX6, because microsatellite instability(MSI)test of the tumor showed high-frequency MSI. Because of the transverse colon obstruction after 2 cycles of pembrolizumab, she underwent right hemicolectomy. Histological examination of the resected specimen revealed no residual tumor cells in the primary tumor and reginal lymph nodes. Immunohistochemistry for mismatch repair proteins(IHC-MMR)showed loss of MSH2 and MSH6 expression. Genetic test identified a MSH2 pathogenic variant leading to the diagnosis of Lynch syndrome. The present case shows the importance of MSI test or IHC-MMR before the treatment of metastatic colorectal cancer.
摘要：
一名47岁的女性被诊断为患有肝脏的横结肠癌，腹膜,淋巴结转移。改良的FOLFOX6(mFOLFOX6)方案作为一线化疗给予,并且在mFOLFOX6的1个周期后接着派姆单抗,因为肿瘤的微卫星不稳定性(MSI)测试显示高频MSI。由于2个周期的pembrolizumab后横结肠梗阻，她接受了右半结肠切除术.切除标本的组织学检查显示，原发肿瘤和区域淋巴结中没有残留肿瘤细胞。错配修复蛋白(IHC-MMR)的免疫组织化学显示MSH2和MSH6表达的丧失。遗传测试确定了MSH2致病变体，从而诊断出Lynch综合征。本病例显示了MSI测试或IHC-MMR在治疗转移性结直肠癌之前的重要性。
