Higher gene expression of the basophil activation markers CD63 and CD203c were detected in several cancers in comparison with normal tissues: cholangiocarcinoma, melanoma, thymoma, glioma, as well as thyroid, renal, hepatic, pancreatic, adrenal, and testicular cancers showed enhanced CD63 expression; increased CD203c was shown in thymoma, colon, renal, and rectum cancers. Here, CD63 is linked to rectal cancer.