Background Gastric cancer (GC) is one of the most common cancers with a poor prognosis worldwide.The calcium sensing receptor (CaSR), a GPCR C family member, is functionally expressed in the entire gastrointestinal tract and serves as a tumor suppressor in colorectal cancer.Mthough molecular expression and physiological role of the CaSR in normal stomach have been demonstrated, its role in tumorigenesis in the upper gastrointestinal tract has not yet been explored.Therefore, we want to provide the first evidence for the CaSR role in human gastric cancer.