Carcinoembryonic antigen (CEA), alpha-fetoprotein, CA 19.9 and CA 125 in advanced colorectal cancer (ACC).

In 111 patients with ACC we studied CEA, FP, CA-125 and CA 19.9 during therapy and follow-up. Marker determination was performed every two months. CEA was elevated (> 5 ng/ml) in 82%, alpha FP (> 15 ng/ml) in 0%, CA-125 (> 38 U/ml) in 37%, CA 19.9 (> 30 U/ml) in 64% of the patients. We did not find significant differences between the sensitivity of CEA alone and that of the combination of CEA + CA-125 (86%), CEA + CA 19.9 (87%), CA-125 + CA-19.9 (71%) and CEA + CA-125 + CA 19.9 (88%). We did not find any correlation between the level of positivity of the markers and the clinical parameters we examined. When serial determinations were carried out, CEA showed the best indication of response to treatment, followed by CA 19.9. In the evaluation of the response to chemotherapy we found that CA 125 presented significant percentages of false-positive (9%) (P < 0.008) and false-negative (8.1%) (P < 0.008) results, compared to CEA and CA 19.9. CA 125 did not demonstrate any utility for the follow-up of patients with colorectal cancer although increased values were found in 37%. We conclude that CEA is currently the best marker for the follow-up of patients with colorectal cancer. The combination of CEA and CA 19.9 had some utility in follow-up, without significantly improving CEA results.