目的 比较RECIST1.1、mRECIST1.1、Choi及早期形态学变化（early morphological change，EMC）4种疗效评估标准对接受伊马替尼（imatinib，IM）治疗的胃肠道间质瘤（gastrointestinal stromal tumors，GISTs）患者的预后预测能力，并分析不同疗效患者的手术时机。 方法 分别采用RECIST1.1、mRECIST1.1、Choi及EMC标准回顾性分析本院66例GISTs患者IM治疗前后的增强CT图像，并根据首次随访疗效反应将患者分为疗效good组和poor组。采用Kaplan-Meier生存曲线分别描绘四种疗效评估标准两组的总生存时间（overall survival，OS）和无进展生存时间（progression-free survival，PFS），通过log-rank检验比较OS及PFS是否存在组间差异。计算首次随访不同疗效患者在治疗后不同时间段的疾病进展（progressive disease，PD）及达到最佳疗效反应（best of response，BOR）的比例以确定合适的手术时机（在BOR比例≥50%且PD比例≤20%的前提下，患者最佳手术时机定义为两者差值最大的治疗时间段）。 结果 EMC标准首次随访疗效good组与poor组间OS（P=0.043）及PFS（P=0.003）差异均有统计学意义。Choi标准2组间仅PFS差异有统计学意义（P=0.002）。RECIST1.1及mRECIST1.1标准首次随访疗效反应分组一致，2组间OS及PFS差异均无统计学意义（均P>0.05）。EMC标准疗效good组即完全反应患者在治疗后1年内50%患者达BOR且无患者发生PD，该组最早PD时间为治疗后1.5年；并且完全反应患者手术与未手术组间的OS差异无统计学意义（P=0.051）。 结论 EMC标准能够早期、准确地对GISTs患者IM治疗后的预后进行分层；且依据EMC标准，完全反应患者可在治疗后1年再考虑手术切除，但这部分患者或许能够选择定期监测等更为保守的治疗措施来代替手术。

Objective To compare the performance of four response evaluation criteria，i.e.，RECIST1.1，mRECIST1.1，Choi，and early morphological change（EMC），in predicting the prognosis of patients with gastrointestinal stromal tumors（GISTs） receiving imatinib（IM） treatment，and to investigate the surgical timing of patients with different responses. Methods A retrospective analysis was performed for the contrast-enhanced computed tomography images of 66 patients with GISTs in our hospital before and after IM treatment using the four response evaluation criteria，and the patients were divided into good response group and poor response group based on the response of the first follow-up. The Kaplan-Meier survival curve was used to describe the overall survival（OS） and progression-free survival（PFS） of the two groups based on the four criteria，and the log-rank test was used for comparison of OS and PFS between groups. The proportion of patients with progressive disease（PD） or the best of response（BOR） at different periods of time after treatment were calculated to determine proper surgical timing（under the premise of ≥50% of the patients with BOR and ≤20% of the patients with PD，with the optimal surgical timing defined as the treatment period with the largest difference between BOR and PD）. Results There were significant differences in OS（P=0.043） and PFS（P=0.003） between the good response group and the poor response group according to the EMC criteria，while there was only a significant difference in PFS（P=0.002） between the two groups based on the Choi criteria. The two groups divided based on the RECIST1.1 and mRECIST1.1 criteria were consistent，with no significant differences in OS and PFS between the two groups（P>0.05）. According to the EMC criteria，50% of the patients in the good response group achieved BOR without PD within 1 year after treatment，and the earliest time to PD was 1.5 years after treatment； for the patients with complete response，there was no significant difference in OS between the surgery group and the non-surgery group（P=0.051）. Conclusion The EMC criteria can accurately stratify the prognosis of patients with GISTs in the early stage after IM treatment； according to the EMC criteria，resection can be considered for the patients with complete response after 1 year of treatment，and instead of surgery，these patients may choose more conservative treatment measures such as regular monitoring.