To address the use of immunocompromised mice, future studies could include testing our probe in a transgenic mouse that expresses human CEA as a syngeneic model of gastric cancer.51 Regarding tumor location, our current method of attaching tumor fragments to the serosal surface of the mouse stomach has room for improvement as most gastric cancers are intraluminal and often infiltrative within the layers of the gastric wall. This evidence concerns the gene CEACAM5 and gastric cancer.