Serum sialic acid and carcinoembryonic levels in the detection and monitoring of colorectal cancer.

Total sialic acid (TSA), total protein (TP), TSA normalized to total TP (TSA/TP), and carcinoembryonic antigen levels were determined in 146 consecutive colorectal patients. These results were compared with results from 73 people with nonmalignant gastrointestinal disease, and with results from 96 normal controls. All malignancies were staged according to the Astler-Coller modification of Dukes' classification for colorectal cancer. All blood samples were drawn before surgical therapy. The TSA/TP ratio for colorectal cancer was 13.4 (mg/gm) in contrast to 12.1 (mg/gm) for pathologic controls, and 9.7 (mg/gm) for normal controls. Student's t test showed a P value less than 0.001 for normal controls and a P value less than 0.001 for pathologic controls. The TSA/TP also showed statistical significance in Dukes A, B2, C, and D subgroups when compared with normal controls. There were only four patients with stage C1 carcinoma, thus statistical analysis would be questionable. In contrast, carcinoembryonic antigen levels showed no significant elevations until Dukes C2 tumors were encountered. These preliminary findings suggest that TSA/TP ratio may detect colorectal cancer patients with less tumor burden and be more beneficial as a tumor marker than CEA for monitoring patients with colorectal cancer.