瘤内微生物组在胃癌（GC）中的作用尚未得到全面评估。在这里，我们探讨了微生物群落与GC预后和治疗效果之间的关系。确定了一些与癌症相关的微生物特征，包括 α 多样性增加、β 多样性差异和幽门螺杆菌丰度减少。调整临床特征后，预后分析显示 2 个门、14 个属和 5 个种与 GC 患者的总生存期相关。此外，2 个门、14 个属和 6 个物种与 II - III 期 GC 患者的辅助化疗 (ACT) 疗效相关。此外，我们将 GC 微生物组结构分为三个具有显着特征的微生物亚型（MS1、MS2 和 MS3）。 MS1亚型表现出高免疫活性、与免疫治疗和丁酸产生相关的微生物群丰富，以及免疫治疗的潜在益处。 MS2 具有最高的 α 多样性和 TFF 通路激活，MS3 的特点是上皮间质转化，与预后不良和 ACT 疗效降低相关。总的来说，这项研究的结果为与 GC 预后和治疗效果相关的微生物特征提供了有价值的见解。

The role of the intratumoral microbiome in gastric cancer (GC) has not been comprehensively assessed. Here, we explored the relationship between the microbial community and GC prognosis and therapy efficacy. Several cancer-associated microbial characteristics were identified, including increased α-diversity, differential β-diversity, and decreased Helicobacter pylori abundance. After adjusting for clinical features, prognostic analysis revealed 2 phyla, 14 genera, and 5 species associated with the overall survival of patients with GC. Additionally, 2 phyla, 14 genera, and 6 species were associated with adjuvant chemotherapy (ACT) efficacy in patients with stage II - III GC. Furthermore, we classified GC microbiome structures into three microbial subtypes (MS1, MS2 and MS3) with distinguishing features. The MS1 subtype exhibited high immune activity and enrichment of microbiota related to immunotherapy and butyric acid-producing, as well as potential benefits in immunotherapy. MS2 featured the highest α-diversity and activation of the TFF pathway, MS3 was characterized by epithelial-mesenchymal transition and was associated with poor prognosis and reduced ACT efficacy. Collectively, the results of this study provide valuable insights into the microbial characteristics associated with GC prognosis and therapy efficacy.