Carcinoembryonic antigen (CEA) and alkaline phosphatase in progressive colorectal cancer with special reference to patient survival.

The prognostic value of serial CEA tests was evaluated in 175 consecutive patients with progressive colorectal cancer who subsequently died of their disease. The upper normal plasma CEA limit was determined to be 8 ng/ml from serial CEA determinations in 31 patients radically operated on for colorectal cancer and observed in median 40 months without evidence of recurrence. A CEA value of greater than 8 ng/ml was highly suggestive of residual disease or recurrence, even when no clinical evidence was present. Approximately 90% of the patients dying from colorectal cancer showed an increase in CEA to greater than 8 ng/ml during the course of the disease. In 63% of the patients CEA increase preceded clinical progression or relapse, with a median time period of 4 months. Sixty-eight per cent of the patients had rising CEA values over an extended time period of many months, 14% had a preterminal increase, 13% had constantly normal and 5% constantly elevated CEA. As 6/9 patients developed a drop in CEA in relation to initiation of chemotherapy without clinical response, it is concluded that CEA is not a reliable indicator of clinical response to chemotherapy. Patients with liver metastases had higher CEA and alkaline phosphatase levels than patients with only localized disease. However, no good statistical correlation between CEA and serum alkaline phosphatase was found in patients with liver metastases (coefficient of correlation r = 0.35). An increase in CEA from normal to above 8 ng/ml predicted a decrease in survival time of median 60% counted from the time of diagnosis. The numerical CEA value was predictive of shortening of survival only when greater than 3000 ng/ml. Such high values were observed only in a minority of the patients (12%). Greater than 1000 U/l (27% of the patients) alkaline phosphatase predicted an extremely poor prognosis, with a median survival of 1 month (range 0.5-4 months). It is concluded that a rise in CEA to greater than 8 ng/ml indicates with high degree of certainty relapse or disease progression in colorectal cancer patients. CEA is not a reliable indicator of clinical response to chemotherapy, and an increase in the CEA level is of little prognostic value concerning survival. Alkaline phosphatase seems to be a more valuable predictor of a worsening of prognosis.