Given the crucial predictive implications of microsatellite instability (MSI) in colorectal cancer (CRC), MSI screening is commonly performed in those with and at risk for CRC. Here, we compared results from immunohistochemistry (IHC) and the droplet digital PCR (ddPCR) MSI assay on formalin-fixed paraffin-embedded tumor samples from 48 patients who underwent surgery for colon and rectal cancer by calculating Cohen’s kappa measurement (k), revealing high agreement between the methods (k= 0.915). We performed Kaplan–Meier survival analyses and univariate and multivariate Cox regression to assess the prognostic significance of ddPCR-based MSI and to identify clinicopathological features associated with CRC outcome. Patients with MSI-high had better overall survival (OS;p= 0.038) and disease-free survival (DFS;p= 0.049) than those with microsatellite stability (MSS). When stratified by primary tumor location, right-sided CRC patients with MSI-high showed improved DFS, relative to those with MSS (p< 0.001), but left-sided CRC patients did not. In multivariate analyses, MSI-high was associated with improved OS (hazard ratio (HR) = 0.221, 95% confidence interval (CI): 0.026–0.870,p= 0.042), whereas the loss of DNA mismatch repair protein MutL homolog 1 (MLH1) expression was associated with worse OS (HR = 0.133, 95% CI: 0.001–1.152,p= 0.049). Our results suggest ddPCR is a promising tool for MSI detection. Given the opposing effects of MSI-high and MLH1 loss on OS, both ddPCR and IHC may be complementary for the prognostic assessment of CRC.
鉴于微卫星不稳定性（MSI）在结直肠癌（CRC）中具有重要的预测意义，MSI筛查通常在对已确诊或存在CRC风险的人群中进行。本研究通过对48例接受结肠癌和直肠癌手术患者的福尔马林固定石蜡包埋肿瘤样本，采用免疫组织化学（IHC）与微滴式数字PCR（ddPCR）MSI检测方法进行比较，并通过计算Cohen's kappa值（k）评估两者一致性，结果显示两种方法具有高度一致性（k=0.915）。我们采用Kaplan-Meier生存分析及单变量、多变量Cox回归分析，评估基于ddPCR的MSI状态的预后意义，并确定与CRC结局相关的临床病理特征。与微卫星稳定（MSS）患者相比，MSI高表达（MSI-high）患者的总生存期（OS；p=0.038）和无病生存期（DFS；p=0.049）更优。按原发肿瘤部位分层分析显示，右侧CRC中MSI-high患者较MSS患者DFS显著改善（p<0.001），而左侧CRC患者中未观察到类似差异。多变量分析表明，MSI-high与OS改善相关（风险比（HR）=0.221，95%置信区间（CI）：0.026–0.870，p=0.042），而DNA错配修复蛋白MutL同源物1（MLH1）表达缺失与较差的OS相关（HR=0.133，95% CI：0.001–1.152，p=0.049）。我们的研究结果表明ddPCR是一种有前景的MSI检测工具。鉴于MSI-high与MLH1缺失对OS的影响相反，ddPCR与IHC在CRC预后评估中可能具有互补价值。
Microsatellite Instability Testing and Prognostic Implications in Colorectal Cancer
肿瘤(癌症)患者之家