Comparative analysis of CA 242 and CA 19-9 serum tumor markers in colorectal cancer patients. A longitudinal evaluation.

OBJECTIVE: Following the encouraging results obtained on CA 242 as an adjunctive marker for colorectal cancer this study was designed to compare the clinical behavior of CA 242 to that of its related marker CA 19-9. PATIENTS AND METHODS: Sera from 630 patients with benign (n = 201) or malignant (n = 429) colorectal diseases were evaluated. Moreover, 50 patients with colorectal cancer were longitudinally monitored during. post-surgical follow-up for either a minimum of 5 years or until time of recurrence. Serum CEA, CA 19-9 and CA 242 levels were determined before treatment and at each scheduled follow-up. RESULTS: The distribution of CA 242 levels in colorectal cancer patients demonstrated a similar positivity rate (32.9%) compared to that of CA 19-9 (29.8%), although both sensitivities were lower than that of CEA (43.8%). Moreover, elevated CA 242 serum levels were found in metastatic disease (58.2%). A longitudinal evaluation demonstrated that serum CEA, CA 19-9 and CA 242 levels were elevated in 63.9%, 63.9% and 66.7% of recurrences. Combined evaluation of CEA, CA 19-9 and CA 242 serum levels in the overall population demonstrated a complementarity of CEA with the latter two markers. Conversely, a highly significant correlation was observed, suggesting that the two assays might recognize the same macromolecular complex. CONCLUSION: CA 242 determination does not seem to offer a particular advantage over CA 19-9, while CEA remains the marker of choice in monitoring colorectal cancer patients.