Significance of postoperative serum level of carcinoembryonic antigen (CEA) and actual half life of CEA in colorectal cancer patients.

The postoperative levels of carcinoembryonic antigen (CEA) and the actual half life (T1/2) of CEA were evaluated to ascertain their potency in predicting the recurrence of colorectal cancer after curative surgery in patients who had an abnormally high level of preoperative carcinoembryonic antigen (CEA, > or = 5 ng/ml). Ninety-four patients who underwent curative surgery were enrolled and 24 patients (25.5%) had recurrence during the follow-up period (median: 30 months, range: 2-69 months). T1/2 of CEA for all patients ranged from 1.2 days to 88.1 days, with a median of 4.4 days. T1/2 of CEA (mean +/- standard deviation) was 11.7 +/- 17.9 days in recurrent patients, whereas it was 6.2 +/- 4.9 days in patients without recurrence (p = 0.0224). The patients' age, gender, size of the tumor, location of the tumor, pre-, and postoperative CEA level, pathologic type of the tumor and Dukes stage had no significance in recurrence. The 1-year, 2-year, and 5-year disease-free survival rates were 95.1%, 81.1%, and 73.8% in patients with postoperative CEA levels less than 5 ng/ml (n = 62), respectively, and 71.4%, 64.8%, and 64.8% in patients with postoperative CEA levels higher than or equal to 5 ng/ml (n = 32), respectively (p = 0.04). Patients were divided into Group S (T1/2 of CEA < 4.4 days, n = 43) and Group L (T1/2 of CEA > or = 4.4 days, n = 51). The 1-year, 2-year, and 5-year disease-free survival rates were 95.3%, 85.1%, and 77.7% in Group S, respectively, and 80%, 67.5%, and 64.1% in Group L, respectively (p = 0.0261). In conclusion, the disease-free survival of colorectal cancer patients was prolonged in patients who had a short T1/2 of CEA or a low level of postoperative CEA. In high-risk colorectal cancer patients with an abnormally high level of preoperative CEA, recurrence may be predicted by checking an early postoperative CEA level and/or by a simple calculation of the actual half life of CEA.