Differences in serum tumor markers between colon and rectal cancer. Comparison of CA 242 and carcinoembryonic antigen.

PURPOSE: We investigated whether there are differences in serum levels of CA 242 and carcinoembryonic antigen (CEA) between patients with colon and rectal cancer. METHODS: Preoperative serum levels of CA 242 and CEA were determined in 153 patients with colon cancer and in 107 patients with rectal cancer. RESULTS: At the recommended cut-off levels for CA 242 and CEA, the overall sensitivity of CA 242 was 39 percent for both colon and rectal cancer, whereas the sensitivity of CEA was 40 percent for colon and 47 percent for rectal cancer. A combination of CA 242 and CEA increased overall sensitivity to 57 percent in colon cancer and to 62 percent in rectal cancer, whereas specificity decreased by 10 percent, compared with CEA alone. In colon cancer either or both markers were elevated in 38, 46, 56, and 84 percent of patients with Dukes Stages A, B, C, and D, respectively. Corresponding figures for rectal cancer were 52, 46, 71, and 87 percent, respectively. CONCLUSIONS: CA 242 showed equal sensitivity for colon and rectal cancer. In Stages A, C, and D, sensitivity of CEA and of a combination of CEA and CA 242 was higher in rectal than in colon cancer, but the difference was not significant. Concomitant use of markers increased sensitivity sharply compared with use of a single marker both in colon and rectal cancer.

Serum CA 242 and CEA detect different patients with recurrent colorectal cancer.

The aim of this study was to investigate the clinical value of CA 242 and CEA in the follow-up of patients with colorectal cancer. Serial serum samples were available for analysis in 67 patients with subsequent recurrence, of which 36 patients had been treated for colonic and 31 patients for rectal cancer. Liver metastases were found in 32 patients, local recurrences in 18 patients, lung metastases in 11 patients and other distant metastases in 6 patients. The same serum samples were used in quantitating the serum levels of both CA 242 and CEA. At the time of clinical recurrence an elevated CA 242 level was found in 41 patients and an elevated CEA level in 49 patients. Thirty-six patients (54%) showed an elevation of both CA 242 and CEA, five patients (7%) had increased CA 242 alone and 13 patients (19%) increased CEA alone. Altogether, 54 patients (81%) showed an elevation of either or both markers at the time of clinical recurrence. Initially CA 242 alone began to rise in 14 patients (21%) and CEA alone in 16 patients (24%). The lead time was calculated from 28 patients that had four or more serum samples available during follow-up. CA 242 increased in median 5,7 months and CEA in median 3,4 months before clinical recurrence (p=0.34). CA 242 was more sensitive for lung metastases (64%) than CEA (45%), whereas CEA was superior to CA 242 in liver metastases (88% versus 72%, respectively) and in local recurrences (56% versus 39%, respectively). Both CA 242 and CEA seem to be useful in early diagnosis of a recurrence in the follow-up of patients with colorectal cancer.