Şenocak Taşçı Elif, Yıldız İbrahim, Erdamar Sibel, Özer Leyla
Department of Medical Oncology, Acıbadem MAA University, Istanbul 12345, Turkey.
Department of Pathology, Acıbadem MAA University, Istanbul 12345, Turkey.
World J Clin Cases. 2023 May 6;11(13):3105-3113. doi: 10.12998/wjcc.v11.i13.3105.
Microsatellite instability (MSI) is a predictive biomarker for cancer immunotherapy. The tumor-agnostic nature of MSI makes it a denominator for immunotherapy in several solid tumors. It can be assessed using next-generation sequencing (NGS), fluorescent multiplex PCR, and immunohistochemistry (IHC).
Here, we report 3 cases with discordant MSI results detected using different methods. A cholangiocellular carcinoma case revealed proficient mismatch repair (MMR) by IHC but high MSI (MSI-H) by liquid NGS. A cervical cancer case revealed deficient MMR by IHC, microsatellite stable by PCR, and MSI-H by NGS. Lastly, an endometrial cancer case revealed proficient MMR by IHC but MSI-H by NGS.
IHC for MMR status is the first choice due to several advantages. However, in cases of indeterminate IHC results, molecular testing by MSI-PCR is preferred. Recently, NGS-based MSI assays are being widely used to detect MSI-H tumors. All three methods have high accuracy; however, the inconsistencies between them may lead to misdiagnosis.
微卫星不稳定性（MSI）是癌症免疫治疗的一种预测性生物标志物。MSI的肿瘤非特异性使其成为多种实体瘤免疫治疗的一个共同指标。可使用下一代测序（NGS）、荧光多重PCR和免疫组织化学（IHC）对其进行评估。
在此，我们报告3例使用不同方法检测出MSI结果不一致的病例。1例胆管细胞癌病例经免疫组化显示错配修复（MMR）功能正常，但经液体NGS检测为高度微卫星不稳定（MSI-H）。1例宫颈癌病例经免疫组化显示MMR功能缺陷，经PCR检测微卫星稳定，但经NGS检测为MSI-H。最后，1例子宫内膜癌病例经免疫组化显示MMR功能正常，但经NGS检测为MSI-H。
由于具有多种优势，MMR状态的免疫组化检测是首选方法。然而，对于免疫组化结果不确定的病例，首选通过MSI-PCR进行分子检测。近年来，基于NGS的MSI检测方法被广泛用于检测MSI-H肿瘤。所有这三种方法都具有很高的准确性；然而，它们之间的不一致可能导致误诊。
