Any clinical benefit from the use of oncofoetal markers in the management of chemotherapy for patients with metastatic colorectal carcinomas?

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.