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.