错配修复缺陷 (dMMR) 胃食管癌 (GEC) 是一个独特的亚组。在局部晚期疾病患者中，既往试验数据表明对新辅助免疫检查点抑制剂（nICI）反应良好。自2019年以来，我机构对新发GEC病例常规进行MMR检测。该研究纳入了诊断为 GEC 的患者（2019-2024 年）。定量数据被描述为中位数和四分位数范围（IQR）；定性数据以数量和百分比的形式描述。在实施常规免疫组织化学检测后，共鉴定出 24 名 dMMR GEC 患者；中位随访时间为 14 个月（IQR 8-27），其中 14 例可能可切除。所有患者均接受治疗前正电子发射断层扫描（PET；中位 SUV 20.9）。迄今为止，在 14 名可能可切除的患者中，4 名接受了立即手术，10 名接受了 nICI 治疗，5 名接受了手术切除。所有治疗方案均包含 PD-1 抑制剂，其中 70% 接受派姆单抗治疗。对 5 名患者进行了重新分期 PET； nICI 后 SUV 中位数为 5.1（范围 4.7-6.3）。所有切除的标本在 nICI 后均出现肉眼溃疡，但 60% (N = 3) 在 nICI 后出现病理完全缓解 (pCR)；一名患者出现接近完全缓解 (nCR)，一名患者出现部分缓解 (pPR)。 pCR 患者的 SUV 降低了 75% 和 82%，nCR 患者降低了 25%，pPR 患者降低了 43%。在有限的经验中，dMMR GEC 对 nICI 有反应，反映了早期临床试验数据。鉴于尽管达到了 pCR，但仍存在持续的代谢活动和可见的溃疡，研究应继续优化用于估计这些患者的 nICI 后 pCR 的工具。© 2024。外科肿瘤学会。

Mismatch repair deficient (dMMR) gastroesophageal cancers (GEC) are a distinct subgroup. Among patients with locally advanced disease, previous trial data suggest a good response to neoadjuvant immune checkpoint inhibitors (nICI).Since 2019, our institution has routinely performed MMR testing for new GEC cases. Patients diagnosed with GEC (2019-2024) were included in the study. Quantitative data are described as the median and interquartile range (IQR); qualitative data are described as quantities and percentages.A total of 24 patients with dMMR GEC were identified following implementation of routine immunohistochemical testing; 14 were potentially resectable with a median follow-up of 14 months (IQR 8-27). All patients underwent pre-treatment positron emission tomography (PET; median SUV 20.9). Among the 14 potentially resectable patients, 4 underwent immediate surgery, 10 were treated with nICI, and 5 underwent surgical resection to date. All regimens included PD-1 inhibitors, with 70% receiving pembrolizumab. Re-staging PET was performed in five patients; the median post-nICI SUV was 5.1 (range 4.7-6.3). All resected specimens had gross ulceration after nICI, but 60% (N = 3) had a pathologic complete response (pCR) following nICI; one patient had a near-complete response (nCR) and one patient had a partial response (pPR). Reduction in SUV was 75% and 82% in the pCR patients, 25% in the nCR patient, and 43% in the pPR patient.dMMR GECs are responsive to nICI in this limited experience, mirroring early clinical trial data. Given persistent metabolic activity and visible ulceration despite pCR, studies should continue to optimize tools for estimating post-nICI pCR in these patients.© 2024. Society of Surgical Oncology.