Background: Worldwide gastric cancer is the fifth most common cancer with poor prognosis. In early stages, it is hard to distinguish gastric cancer from benign gastric diseases, resulting in delayed diagnosis. There is a need to develop a biomarker for differentiating between gastric cancer and benign gastric diseases. Serum cholinesterase is synthesized in liver and released into plasma, and it has an important role in oncogenesis.

Objectives: To determine the correlation between serum cholinesterase activity and gastric cancer, in comparison to benign gastric diseases.

Subjects and Methods: A case control study carried out at Medical City Directorate\ Gastroenterology, Hepatology Hospital, and at Oncology Teaching Hospital from April 2022 to September 2022. It involved 25 patients with gastric cancer and age matched 25 patients with benign gastric diseases. Serum cholinesterase activity was determined by a colorimetric method..

Results: There was a significant difference in the mean level of serum cholinesterase between gastric cancer group (5339.28 U/L±1816) and benign gastric diseases group (7516.92 U/L±2351) with (P value<0.001). Significant association between low levels of serum cholinesterase and early cancer stages and grades (P value<0.001). Serum cholinesterase showed 60% sensitivity and 80% specificity in differentiating between gastric cancer and benign gastric diseases with optimal cutoff value of 5568U\L.

Conclusions: Serum cholinesterase can be considered as a potential rapid and non-invasive biomarker for differentiating between gastric cancer and benign gastric diseases.