胃腺鳞癌（GASC）是胃癌的一种罕见亚型。对GASC治疗的研究很少，其结果通常很差。我们调查了GASC的临床特征，免疫表型，并确定了这些患者的最佳治疗方式。在4034例胃癌患者中，发现14例（占0.35%）GASC患者。10例III期GASC患者的中位肿瘤大小为6.8厘米，所有这些患者都接受了根治性胃切除术后的辅助治疗。中位无进展生存期（PFS）和总生存期（OS）分别为6.0和11.5个月。两例IV期GASC患者接受了前线免疫治疗。他们的中位PFS和OS分别为9.0和12.5个月。在免疫表型中，25.0%（n = 3），75.0%（n = 9）和33.3%（n = 4）的样本缺乏错配修复（dMMR）蛋白质，综合阳性分数（CPS）≥1和CPS≥10。单因素分析表明，PD-L1≥5%（HR：0.12；95% CI：0.01-0.97；p = 0.047）与优越的OS显著相关。一位CPS≥10和dMMR蛋白质的IV期患者接受了尼伏单抗单药作为前线治疗，结果是14个月的PFS。我们回顾性评估了台北榮民總醫院的GASC患者。评估了临床特征和治疗结果。充分的样本通过IHC染色检查代表免疫治疗的生物标志物。GASC患者更可能得出CPS和dMMR的阳性结果。应检查生物标志物，并考虑免疫治疗作为前线系统性治疗。版权所有 ©2023年中国医学协会。

Gastric adenosquamous carcinoma (GASC) is a rare subtype of gastric cancer. Research on GASC treatment is limited, and its outcome is usually poor. We investigated the clinical features, immunoprofile of GASC and determined the optimal treatment modality for these patients.Total 14 (0.35%) GASC patients were found among 4034 gastric cancer patients. The median tumor size was 6.8 cm in 10 patients with stage III GASC, and all these patients underwent radical gastrectomy followed by adjuvant therapy. The median progression-free survival (PFS) and overall survival (OS) were 6.0 and 11.5 months, respectively. Two patients with stage IV GASC received frontline immunotherapy. Their median PFS and OS were 9.0 and 12.5 months. In immunoprofiling, 25.0% (n = 3), 75.0% (n = 9), and 33.3% (n = 4) of the samples had deficient mismatch repair (dMMR) protein, combined positive score (CPS) of ≥1, and CPS of ≥10, respectively. The univariate analysis revealed that PD-L1 ≥5% (HR: 0.12; 95% CI: 0.01-0.97; p = 0.047) was significant associated with superior OS. One stage IV patient with CPS ≥10 and dMMR proteins received nivolumab monotherapy as frontline treatment that resulted 14-months PFS.Patients with GASC from Taipei Veterans General Hospital were retrospectively reviewed. Clinical features and treatment outcomes were evaluated. Adequate samples were examined for surrogate biomarkers for immunotherapy by IHC staining.Patients with GASC are more likely to yield positive results for CPS and dMMR. Biomarkers should be examined, and immunotherapy can be considered as frontline systemic treatment.Copyright © 2023, the Chinese Medical Association.