OBJECTIVES To determine the diagnostic accuracy of magnetic resonance tumor regression grade (mrTRG) for pathological complete response (pCR) and its correlation with pathological findings. METHODS Original studies that investigated the correlation of mrTRG with pathological tumor regression grade and pathological T stage were identified in MEDLINE and EMBASE up until August 31, 2018, according to PRISMA guidelines. The search terms included colorectal cancer, chemoradiation therapy, magnetic resonance imaging, and response or regression. Meta-analytic summary sensitivity and specificity for pathologic complete response (pCR) and pathologic T1 or lower than T1 stage (≤ypT1) were calculated using a bivariate random-effects model. The sensitivity and specificity were calculated in both mrTRG 1 and mrTRG 1 or 2, respectively. RESULTS Six studies with 916 patients were included. The meta-analytic summary sensitivity and specificity of mrTRG 1 for pCR were 32.3% (95% CI, 18.2-50.6%) and 93.5% (95% CI, 91.5-95.1%), while for ≤ypT1 they were 31.8% (95% CI, 16.2-53.0%) and 94.7% (95% CI, 91.9-96.5%). On the contrary, sensitivity and specificity of mrTRG 1 or 2 for pCR were 69.9% (95% CI, 60.2-78.1%) and 62.2% (95% CI, 56.2-67.8%), while those for ≤ypT1 were 71.4% (95% CI, 61.6-79.6%) and 67.7% (95% CI, 59.8-74.7%). CONCLUSIONS mrTRG 1 showed high specificity for pCR and ≤ypT1, but suboptimal sensitivity. mrTRG 1 or 2 showed higher sensitivity for pCR and ≤ypT1, but lower specificity. Because of the suboptimal sensitivity of mrTRG 1, it might be limited as a criterion for less aggressive treatment after neoadjuvant chemoradiotherapy. KEY POINTS • Magnetic resonance tumor regression grade 1 shows high specificity for pCR and ≤ypT1, but suboptimal sensitivity. • Magnetic resonance tumor regression grade 1 or 2 shows higher sensitivity for pCR and ≤ypT1, but lower specificity than magnetic resonance tumor regression grade 1 alone.

中文翻译：

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直肠癌新辅助放化疗后病理学完全缓解的 MR 肿瘤消退等级：准确性的系统评价和荟萃分析。

目的 确定磁共振肿瘤消退等级 (mrTRG) 对病理完全缓解 (pCR) 的诊断准确性及其与病理结果的相关性。方法根据 PRISMA 指南，截至 2018 年 8 月 31 日，在 MEDLINE 和 EMBASE 中确定了调查 mrTRG 与病理性肿瘤消退等级和病理性 T 分期相关性的原始研究。搜索词包括结直肠癌、化放疗、磁共振成像以及反应或消退。使用双变量随机效应模型计算病理完全缓解 (pCR) 和病理 T1 或低于 T1 分期 (≤ypT1) 的荟萃分析总结敏感性和特异性。分别在 mrTRG 1 和 mrTRG 1 或 2 中计算灵敏度和特异性。结果 纳入了 6 项研究，共 916 名患者。mrTRG 1 对 pCR 的荟萃分析总结敏感性和特异性分别为 32.3%（95% CI，18.2-50.6%）和 93.5%（95% CI，91.5-95.1%），而对于≤ypT1，它们为 31.8%（95 % CI，16.2-53.0%）和 94.7%（95% CI，91.9-96.5%）。相反，mrTRG 1 或 2 对 pCR 的敏感性和特异性分别为 69.9%（95% CI，60.2-78.1%）和 62.2%（95% CI，56.2-67.8%），而≤ypT1 的敏感性和特异性为 71.4%（ 95% CI，61.6-79.6%）和 67.7%（95% CI，59.8-74.7%）。结论 mrTRG 1 对 pCR 和≤ypT1 表现出高特异性，但灵敏度不佳。mrTRG 1 或 2 对 pCR 和≤ypT1 表现出更高的敏感性，但特异性较低。由于 mrTRG 1 的敏感性不佳，它作为新辅助化放疗后较不积极治疗的标准可能受到限制。要点 • 磁共振肿瘤消退 1 级显示对 pCR 和≤ypT1 具有高特异性，但灵敏度不佳。• 磁共振肿瘤消退 1 级或 2 级对 pCR 和≤ypT1 的敏感性更高，但特异性低于单独的磁共振肿瘤消退 1 级。