We set out to determine whether GPA33 is distinct from or overlaps with Claudin 18.2 as a theranostic target in OAC.<h4>Methods</h4>A microarray from n = 106 patients, composed of cancer, normal squamous tissue, normal gastric tissue, and metastatic lymph nodes, was used to compare the expression of GPA33 and Claudin 18.2. This evidence concerns the gene GPA33 and cancer.