Gut microbiota have been implicated in the development of cancer. Colorectal and gastric cancers, the major gastrointestinal tract cancers, are closely connected with the gut microbiome. Nevertheless, the characteristics of gut microbiota composition that correlate with gastric cancer are unclear. In this study, we investigated gut microbiota alterations during the progression of gastric cancer to identify the most relevant taxa associated with gastric cancer and evaluated the potential of the microbiome as an indicator for the diagnosis of gastric cancer. Compared with the healthy group, gut microbiota composition and diversity shifted in patients with gastric cancer. Different bacteria were used to design a random forest model, which provided an area under the curve value of 0.91. Verification samples achieved a true positive rate of 0.83 in gastric cancer. Principal component analysis showed that gastritis shares some microbiome characteristics of gastric cancer. Chemotherapy reduced the elevated bacteria levels in gastric cancer by more than half. More importantly, we found that the genera Lactobacillus and Megasphaera were associated with gastric cancer.

Key Points

• Gut microbiota has high sensitivity and specificity in distinguishing patients with gastric cancer from healthy individuals, indicating that gut microbiota is a potential noninvasive tool for the diagnosis of gastric cancer.

• Gastritis shares some microbiota features with gastric cancer, and chemotherapy reduces the microbial abundance and diversity in gastric cancer patients.

• Two bacterial taxa, namely, Lactobacillus and Megasphaera, are predictive markers for gastric cancer.

肠道菌群与癌症的发展有关。大肠胃癌是大肠癌和胃癌，与肠道微生物组密切相关。然而，尚不清楚与胃癌有关的肠道菌群组成的特征。在这项研究中，我们调查了胃癌进展过程中肠道菌群的变化，以确定与胃癌相关的最相关的分类单元，并评估了微生物组作为胃癌诊断指标的潜力。与健康组相比，胃癌患者肠道菌群组成和多样性发生变化。使用不同的细菌设计随机森林模型，该模型在曲线值下提供了0.91的面积。验证样本的真实阳性率为0。胃癌83例。主成分分析表明，胃炎具有胃癌的某些微生物组特征。化学疗法将胃癌中升高的细菌水平降低了一半以上。更重要的是，我们发现乳杆菌和巨噬细胞与胃癌有关。

关键点

•肠道菌群在区分胃癌患者和健康个体方面具有很高的敏感性和特异性，这表明肠道菌群是诊断胃癌的潜在无创工具。

•胃炎与胃癌共有一些微生物菌群特征，化学疗法可降低胃癌患者的微生物丰富度和多样性。

•两种细菌类群，即乳酸杆菌和巨球藻，是胃癌的预测标记。