Objective: To investigate the immunophenotypic and molecular biological characteristics of patients with elevated serum alpha-fetoprotein (AFP) and enteroblastic differentiated gastric adenocarcinoma (GAED). Methods: The clinicopathological data of 13 patients with elevated serum AFP and GAED admitted to Shanxi Cancer Hospital from 2018 to 2020 were collected. Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to analyze the immune markers and molecular biological characteristics of the pathological tissues of the patients. Kaplan-Meier method and log rank test were used for survival analysis. Results: Among the 13 patients with GAED, 12 were male and 1 was female, aged 41-70 years, with a median age of 64 years. The lesions were mainly located in the gastric antrum (5 cases) and gastric body (4 cases). IHC results showed that the tumor embryonic protein (AFP, SALL4, GPC3), intestinal epithelial differentiation protein (CDX-2, CD10), and some original intestinal epithelial phenotype markers (OCT3/4, Claudin6) were expressed in the tumor tissues. Combined application of multiple markers can reduce the rate of missed diagnosis. Among the 13 patients, 12 had at least one mutation (1 mutation: 1 case, 2-5 mutations: 3 cases, 6-15 mutations: 8 cases), and 1 case was not detected. The gene with the highest mutation frequency was TP53 (10 cases), and other mutant genes included EPHB1 (3 cases), ATRX (2 cases), EPHA5 (2 cases), GATA3 (2 cases), LRP1B (2 cases) and MAP2K4 (2 cases) were also detected. Three of the 13 patients had structural variations, which were C14orf177-GNAS, AIM1-FGFR3, and EPHA6-ROS1 gene rearrangements. All 13 patients had copy number variation, and 11 patients had copy number variation of more than 2 genes. The common amplification genes were IRS2 (5 cases), PTEN (5 cases), GNAS (4 cases), CCNE1 (3 cases), CEBPA (3 cases), PCK1 (3 cases) and ERBB2 (2 cases). The common deletion genes were SOX2 (5 cases) and MYC (5 cases). Among the 13 patients, 4 died, and 2 of the dead patients had liver metastasis. There were 4 patients with disease-free survival and 5 patients with disease progression, including 3 cases of abdominal metastasis and 2 cases of liver metastasis. The 3-year survival rate of patients was 65.9 %, and the 3-year progression-free survival rate was 30.7 %. Gene LRP1B point mutation was associated with poor prognosis (P＜0.001). There was no significant improvement in the prognosis of patients treated with immunotherapy compared with those treated with chemotherapy alone (P=0.595), but the prognosis of patients treated with postoperative chemotherapy or postoperative chemotherapy plus immunotherapy was better than that of patients treated with surgery alone (P＜0.05). Conclusions: Elevated serum AFP with GAED is a highly invasive tumor with unique molecular characteristics, often accompanied by multiple molecular events. TP53 mutation is the most common type of gene mutation. In addition, some cases are accompanied by HER2 amplification and gene rearrangement.
目的： 探讨血清甲胎蛋白（AFP）升高伴肠母细胞分化胃腺癌（GAED）患者的免疫表型和分子生物学特征。 方法： 收集2018—2020年山西省肿瘤医院收治的13例血清AFP升高且伴有GAED患者的临床病理资料，应用免疫组织化学（IHC）及二代测序方法对13例血清AFP升高伴GAED患者的病理组织进行免疫标志物和分子生物学特征分析，生存分析采用Kaplan-Meier法和Log rank检验。 结果： 13例GAED患者中，男12例，女1例，年龄41～70岁，中位年龄64岁，病灶位置以胃窦部（5例）、胃体部（4例）为主。IHC显示可表达瘤胚胎蛋白（AFP、SALL4、GPC3）、肠上皮分化蛋白（CDX-2、CD10）和一些原始肠上皮表型标志物（OCT3/4、Claudin6），联合应用多种标志物诊断可降低漏诊率。13例患者中，12例存在至少1个基因突变（1个基因突变：1例，2～5个基因突变：3例，6～15个基因突变：8例），1例未检测到突变。突变频率最高的基因是TP53（10例），其他突变基因包括EPHB1（3例）、ATRX（2例）、EPHA5（2例）、GATA3（2例）、LRP1B（2例）和MAP2K4（2例）。13例患者中3例存在基因结构变异，分别为C14orf177-GNAS、AIM1-FGFR3、EPHA6-ROS1基因重排。13例患者均存在拷贝数变异，11例患者存在2个以上基因的拷贝数变异。常见的扩增基因为IRS2（5例）、PTEN（5例）、GNAS（4例）、CCNE1（3例）、CEBPA（3例）、PCK1（3例）、ERBB2（2例），常见的缺失基因为SOX2（5例）、MYC（5例）。13例患者中，死亡4例，死亡患者中有2例出现肝转移；无病生存患者4例，5例患者病情进展，其中3例出现腹腔转移，2例出现肝转移。血清AFP升高伴GAED患者3年生存率为65.9%，3年无进展生存率为30.7%。基因LRP1B点突变与预后不良有关（P＜0.001）。行免疫治疗较单纯化疗的患者预后无明显改善（P=0.595），但进行术后化疗或术后化疗加免疫治疗较只进行手术患者预后好（均P＜0.05）。 结论： 血清AFP升高伴GAED是一种具有高度侵袭性的肿瘤，有独特的分子特征，往往同时伴有多个分子事件，TP53突变是其最常见的基因突变类型，此外，部分患者伴有人表皮生长因子受体2扩增和基因重排。.