Prognostic significance of the immunohistochemical localization and serological detection of CA19-9 tumor antigen in colon carcinoma.

Purpose: This study was carried out in order to evaluate the expression of CA19-9 antigen in serum and tissue samples of colon cancer patients in relation with other pathological prognostic factors.

Materials And Methods: 99 patients diagnosed with colon cancer entered the study. The CA19-9 antigen was measured in the serum by ELISA (cut-off value 37 IU/L) and in malignant tissue samples by immunohistochemistry using Mab 192. Seventy-five tissue samples of normal colon served as controls.

Results: In cancer cells the CA19-9 antigen was expressed on the cell membrane, in the lumen and in the cytoplasm. The expression of the antigen in the cytoplasm and also the high serum values of the tumor marker correlated well with more differentiated tumors (grade I and II) and with positive lymph nodes cases. There was also a positive correlation between cytoplasmic localization of CA19-9 and high levels in the serum.

Conclusion: The presence of CA19-9 in the cytoplasm reflects the malignant potential of the colon cancer cell. In less differentiated tumors (grade III) loss of antigenicity is observed. The two methodologies correlate well with each other and their simultaneous application confers to the better use and understanding of this tumor-associated antigen.