Microsatellite instability (MSI) implies the deletion of mismatch repair genes caused by DNA methylation or gene mutation. MSI is a good predictor for efficacy of 5-fluorouracil (FU)-based chemotherapy in the treatment of colorectal cancer. Some gastric cancer studies have reported that MSI has no apparent impact on prognosis after patients receive 5-FU-based adjuvant chemotherapy. However, other studies suggest that high-frequency MSI (MSI-H) status reduced survival in patients receiving 5-FU-based adjuvant chemotherapy. Thus, the correlation between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer remains controversial. We performed a PubMed, Embase, and Cochrane search to retrieve studies that explore the correlation between MSI status and 5-FU-based adjuvant chemotherapy efficacy in gastric cancer. After extracting 65 potentially eligible studies, four were ultimately included in this meta-analysis using Stata software (ver. 12.0). For each study, we estimated the hazard ratio (HR) value for overall survival (OS), and HR was extracted per the survival curve in the studies. Heterogeneity was estimated using the random-effects model. Overall, 1174 patients after operation were included: 84 patients were classed as MSI-H and 1090 as microsatellite stable (MSS)/low-frequency MSI (MSI-L). For the four studies, the overall estimate of HR for OS between MSI-H and MSS/MSI-L groups was 1.90 (95% confidence interval: 0.91-3.93; p = 0.08). We found no correlation to exist between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer. Although MSI can effectively predict efficacy of 5-FU-based chemotherapy in patients with colorectal cancer, the correlation between MSI status and efficacy of 5-FU-based adjuvant chemotherapy for gastric cancer remains controversial. This meta-analysis suggests that MSI status is unrelated to efficacy of 5-FU-based adjuvant chemotherapy in gastric cancer, and more prospective clinical studies are needed to further investigate predictive value of MSI status in patients with gastric cancer who, after operation, receive 5-FU-based adjuvant chemotherapy.

中文翻译：

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通过微卫星不稳定性预测基于5-氟尿嘧啶的辅助化疗在胃癌中的疗效：一项荟萃分析。

微卫星不稳定性（MSI）表示由DNA甲基化或基因突变引起的错配修复基因的缺失。MSI是基于5-氟尿嘧啶（FU）的化学疗法治疗结直肠癌疗效的良好预测指标。一些胃癌研究报告说，患者接受5-FU辅助化疗后，MSI对预后没有明显影响。但是，其他研究表明，接受5-FU辅助化疗的患者的高频MSI（MSI-H）状态降低了生存率。因此，MSI状态与基于5-FU的辅助化疗对胃癌的疗效之间的相关性仍存在争议。我们进行了PubMed，Embase和Cochrane搜索，以检索探索MSI状态与基于5-FU的胃癌辅助化疗疗效之间相关性的研究。在提取65项可能合格的研究后，最终使用Stata软件（版本12.0）将4项纳入荟萃分析。对于每项研究，我们估算了总体生存率（OS）的危险比（HR）值，并根据研究中的生存曲线提取了HR。使用随机效应模型估计异质性。总共包括1174例术后患者：84例被归类为MSI-H，1090例被归类为微卫星稳定（MSS）/低频MSI（MSI-L）。对于这四项研究，MSI-H组和MSS / MSI-L组之间的OS HR总体估计为1.90（95％置信区间：0.91-3.93； p = 0.08）。我们发现MSI状态与基于5-FU的胃癌辅助化疗疗效之间不存在关联。尽管MSI可以有效预测基于5-FU的化学疗法对结直肠癌的疗效，但MSI状况与基于5-FU的辅助化疗对胃癌的疗效之间的相关性仍存在争议。这项荟萃分析表明，MSI状况与基于5-FU的辅助化疗在胃癌中的疗效无关，并且需要更多的前瞻性临床研究来进一步调查胃癌患者术后接受MSI状况的预测价值基于5-FU的辅助化疗。