Immunohistochemical Expression of Carbohydrate Antigen 19–9 in Colorectal Carcinoma

Objectives: Carbohydrate antigen 19‐9 (CA19‐9) is one of the most representative tumor markers in colo‐rectal carcinomas. We studied the immunohistochemi‐cal expression of CA19‐9 in primary colorecta) carcinoma to identify its signiflcance as a prognostic factor. Methods: The avidin‐hiotin‐peroxidase complex method was used for CA19‐9 staining in sections from 149 patients with primary colorectal carcinoma. The data were studied by univariate and multivariate analyses. Results: 86 tumors (56%) stained positively. The staining pattern was classified into three groups: group I (a stromal type, 22 tumors), group II (an apical and/or cytoplasmic type, 64 tumors), and group 111 (no staining, 63 tumors). Eight clinicopathologic variables showed a significant relationship with the staining pattern of CA19‐9. The 5‐yr survival rate of the group I subjects was significantly lower than that of the other two groups. With the multivariate analysis, the staining pattern of CA19‐9 proved to be one of the independent prognostic variables. Conclusions: In addition to conventional prognostic factors, the staining pattern of CA19‐9 is considered to be of value in predicting the prognosis of patients with colorectal carcinomas.