Carbohydrate antigen expression in colorectal cancer.

Several major alterations in glycosylation of glycoproteins and glycolipids occur in colorectal cancer resulting in the expression of cancer associated antigenic epitopes. These changes can occur either in the outer peripheral, middle, or inner core regions of the carbohydrate side chains. The major changes are increased expression, inappropriate expression, deletion and modification of antigenic structures present in normal colorectal tissues. These changes are illustrated by recent studies on the expression of several blood group antigens such as A,B,H, and Leb antigens, modified blood group related antigens such as sialosyl Lea, CA 50, SPan-1, Lex (X) and Ley (Y) antigens and inner core carbohydrate antigen such as T, Tn and Sialosyl-Tn antigens. These changes also occur in adenomatous polyps and appear to correlate with parameters of malignant potential. Thus, these carbohydrate antigens may serve as premalignant markers which may be useful in identification and screening of subjects at high risk for developing colorectal cancer. Carbohydrate containing cancer and malignant markers show considerable promise as potential candidates in immunodetection, staging and therapy of colorectal cancer.