Chinese researchers from Shanghai Jiao Tong University have identified a previously unknown bacterial contributor to stomach cancer progression. While Helicobacter pylori is a known factor, this new study, published in the journal Gut, reveals that *Streptococcus anginosus*, a common oral bacterium, significantly accelerates the growth of stomach tumors. The research team, led by Fang Jingyuan and including Dr. Zhou Chengbei, discovered that *S. anginosus* produces methionine, an amino acid that activates the MAT2A enzyme within cancer cells, promoting their growth and spread. This finding is crucial for early detection, as many stomach cancer patients are diagnosed at advanced stages, and could revolutionize diagnostic methods by analyzing bacterial signatures in stool samples.