Any Clinical Benefit From the Use of Oncofoetal Markers in the Management of Chemotherapy for Patients with Metastatic Colorectal Carcinomas

Abstract Aims : Computed tomography (CT) is the reference technique for evaluating response to chemotherapy. The potential helpfulness of tumour markers is debated. Materials and methods: From March 1997 to January 1999, 91 consecutive patients receiving chemotherapy for metastatic colorectal carcinoma underwent whole-body spiral CT, estimates of anti-carcinoembryonic antigen (CEA) and CA19-9 every 8 weeks. Results: CEA and CA19-9 levels were above normal in 78 (85.7%) and 61 (67.5%) patients, respectively. Tumour response evaluation according to the RECIST criteria was obtained at 8-week evaluation in 83 (91%) patients. The positive predictive values (PPV) for response of a decrease of the marker levels were 53.8 for CEA and 41.7 for CA19-9 using a 30% decrease threshold, and 60/52.2, respectively, using a 50% decrease threshold. Meaningful PPV values (>90%) for progression of an increase of the marker levels were only obtained using the 200% increase threshold for CEA alone or a combination of CEA and CA 19-9. A 100% CEA increase between baseline and the 8-week evaluation was correlated to overall survival ( P =0.0023). The need for a radiological confirmation of tumour progression could be avoided by the systematic dosage of tumour markers at baseline and after 8 weeks of treatment only in a sub-population of 13% of the patients with a 200% increase of CEA or CA 19-9 at 8 weeks. Conclusions: CEA, CA 19-9, or both should be used with caution for tumour response evaluation to chemotherapy in addition to CT in metastatic colorectal carcinoma.