Cancer-associated carbohydrate antigens for clinical diagnostic markers--its effectiveness and limitations.

Cancer cells express various aberrant glycoconjugates. Several kinds of carbohydrate antigens have been used for the serological tumor markers. In particular, the serological level of sialylated carbohydrate antigens, which contain the sialic acid residue in their structure, showed effectiveness in diagnosing cancer behavior. Although large number of carbohydrate antigens in serum of cancer patients was elevated broadly in various cancers, each tumor marker has different sensitivity and specificity for each cancer. Therefore, the combined use of several tumor markers which have different characteristics is effective for better sensitivity in diagnosing cancer behavior. The mechanism of synthesizing cancer-associated carbohydrate antigens is not fully understood because it is very complex. In addition, new cancer-associated carbohydrate antigens are also identified by molecular oncological studies. Those investigations are considered to develop more effective tumor markers to diagnose cancer behavior.