Serological studies on CEA, CA 19-9, STn and SLX in colorectal cancer

Sialyl Le(x) (NeuAca2-3Galb1-4(Fuca1-3)GlcNAc1-R) (SLX) was introduced as cancer-associated. In this study, serological expression of SLX was examined with that of carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA 19-9) and sialyl Tn antigen (STn) concerning the prognosis and clinicopathological findings of patients with colorectal carcinoma.

One hundred and seventeen patients were operated on for colorectal cancer and were enrolled in this study. Serum CEA, CA 19-9, STn and SLX levels were measured pre-operatively by radioimmunoassays and the cut-off values were 5ng/ml, 37U/ml, 45U/ml, and 38U/ml, respectively.

Serologically, the positive rates of CEA, CA 19-9, STn and SLX antigens were 33.3, 26.5, 23.1, and 17.1%, respectively. The CEA, CA 19-9 and SLX are stage specific in clinical stage. In the CEA, CA 19-9, STn, SLX-positive patients, 5-year survival rates were 41.0, 29.7, 50.1, and 29.1%, respectively. In the tumor marker-positive patients, prognosis was significantly poorer than in the negative patients. In the patients with Curability A or B, the difference in survival between the SLX-positive and negative patients was significant. Multivariate analysis revealed that significant prognostic indicators were accompanying liver metastasis, histological type, depth of invasion, CEA and SLX.

The combination assay of serum CEA, CA 19-9, STn and SLX will be beneficial for diagnosis and follow-up of colorectal cancer.