Prognostic value of CA 19.9 levels in colorectal cancer.

Pretreatment serum levels of carbohydrate antigen 19.9 (CA 19.9) and carcinoembryonic antigen were measured in 293 patients with colorectal cancer. Carbohydrate antigen 19.9 was above the cut-off limit of 37 U/mL in 35% of patients. Carbohydrate antigen 19.9 sensitivity was related to tumor stage. Carcinoembryonic antigen was above the cut-off level of 3.5 ng/mL in 61% of patients, and the simultaneous use of two markers increased sensitivity to 66%. The main use of pretreatment levels of CA 19.9 in locoregional cancer is in prognosis. Carbohydrate antigen 19.9 provided more prognostic information than that obtained by conventional staging methods. In patients with Dukes' C tumors, additional information was obtained for allocation of these patients into groups at low or high risk of recurrence. Prognostic significance of carcinoembryonic antigen was not independent of Dukes' classification.