缺乏 DNA 错配修复 (dMMR) 的结直肠癌 (CRCs) 占所有 CRCs 的 15%。缺乏 MMR 是与固体肿瘤中的免疫检查点抑制剂 (ICIs) 敏感性相关的预测性生物标志物，包括 CRC。ICIs 在转移性 CRC 中的显著疗效导致对其在局限性疾病的围手术期和术后治疗的评估。在少数局限性 dMMR CRC 患者中进行的多个前瞻性 2 期研究表明，围手术期 ICI 的完全临床和病理学反应率较高 (60%-100%)，ICI 相关毒性反应的 3 级或更高级别率较低。鉴于这些研究的中位随访时间为 12 至 25 个月，需要进行较长期的监测以确定反应的持久性，并确保在接受非手术管理的患者中没有损害肿瘤学结果。对于直肠癌患者而言，围手术期 ICI 治疗尤为有吸引力，因为骨盆放疗和全直肠系膜切除手术会伴随显著的致残率。正在进行和计划中的前瞻性 2 期试验将提供进一步的数据，包括最佳围手术期治疗持续时间、ICI 单药治疗 vs. 联合治疗以及是否需要术后 ICI 治疗等重要问题。虽然本综述发现围手术期免疫治疗对局限性 dMMR CRC 的早期结果显示了高比例的重大和完全病理学反应，但需要长期随访数据以确保不会损害肿瘤学结果，并且理想情况下会有所改善。在局限性 dMMR CRC 中的围手术期 ICI 治疗代表了一种潜在的范式转变，对器官保留具有重要意义。

Colorectal cancers (CRCs) with deficient DNA mismatch repair (dMMR) account for 15% of all CRCs. Deficient MMR is a predictive biomarker associated with responsiveness to immune checkpoint inhibitors (ICIs) in solid tumors, including CRC. The remarkable effectiveness of ICIs in metastatic CRC has led to their evaluation in the neoadjuvant and adjuvant treatment of localized disease.Multiple prospective phase 2 studies in limited numbers of patients with localized dMMR CRC demonstrate high complete clinical and pathological response rates (60%-100%) to neoadjuvant ICIs, with low rates of grade 3 or higher ICI-related toxic effects. Given the median follow-up of 12 to 25 months in these studies, longer-term monitoring is needed to determine the durability of response and to ensure that oncologic outcomes are not compromised in patients undergoing nonoperative management. Neoadjuvant ICI therapy is especially attractive for patients with rectal cancer given the significant morbidity that accompanies pelvic irradiation and total mesorectal excision. Ongoing and planned prospective phase 2 trials will provide further data on important issues, including optimal neoadjuvant treatment duration, ICI monotherapy vs combination, and the need for adjuvant ICI therapy.While this review found that early results of neoadjuvant immunotherapy for localized dMMR CRC show high rates of major and complete pathological response, longer-term follow-up data are needed to ensure that oncologic outcomes are not compromised and are ideally improved. Neoadjuvant ICI therapy in localized dMMR CRC represents a potential paradigm shift with implications for organ preservation.