We found that Mg‐CaCO3 could directly kill tumor cells and inhibit tumor growth in mice tumor transplantation models, which is consistent with previous reported hydrogen therapies.[6, 10, 11, 45] Moreover, we observed that CAFs significantly down‐regulated a series of pro‐tumor factors and immune suppression chemokines including Cxcl1 and Cxcl12 after Mg‐CaCO3 treatment. This evidence concerns the gene CXCL12 and neoplasm.