CA 19-9 antibody, a carbohydrate antigenic determinant identified as a sialylated lacto-N-fucopentose II, is related to the Lewis blood group. CA 19-9 might play a role in the process of tumor progression as an adhesion molecule. The CA 19-9 antibody has been shown to label adenocarcinomas of the pancreas, stomach, breast, colon and gall bladder. CA 19-9 is also expressed in primary and metastatic ovarian carcinomas. Studies show that CA 19-9 positive expression may be a predictor of increased cancer mortality.