[Clinical importance of the determination of the hydrophobic forms of serum carcinoembryonic antigen (CEA) in metastatic cancer of the colon].

Thirty-four patients with metastatic colon cancer were treated with 5 fluorouracil and folinic acid. The follow-up of disease was evaluated by tomodensitometric CT-scan analysis and by serum CEA determination. In addition, a study of the different CEA molecular forms separated by Triton X114 partitioning, immunoprecipitation and immunoblotting was completed. Concerning the aqueous phase, no relationship appeared between the pattern of CEA species and the outcome of chemotherapy. Opposingly, the analysis of the hydrophobic phase gave results closely correlated to chemotherapeutic response. In 19/34 patients, the hydrophobic CEA forms were absent or weakly expressed; out of these patients, 16/19 underwent a successful response to chemotherapy regimen. Opposingly, all of the remaining 15 patients expressing high levels of hydrophobic CEA species were non-responders. The present study thus gives new means for predicting the outcome of 5 fluorouracil-folinic acid chemotherapy by screening the molecular CEA forms expressed in the serum of patients with metastatic colon cancer.