Serial plasma carcinoembryonic antigen measurements in the management of metastatic colorectal carcinoma.

Serial carcinoembryonic antigen (CEA) measurements were evaluated in a group of 263 patients undergoing systemic chemotherapy for metastatic colorectal carcinoma. Initial CEA levels were not found to be of value in predicting the likelihood of subsequent tumor response. Although a general relation between serial CEA measurements and clinical tumor measurements was noted, these measurements were discordant in a substantial proportion of patients. Tumor measurements as an index of response to therapy were strongly correlated with survival, whereas changes in CEA values and patient survival were not correlated at a statistically significant level. Serial CEA measurements were perhaps of some value in predicting progression of malignant disease, and were roughly comparable to serum alkaline phosphatase assay in assessing response of liver metastasis to chemotherapy. Overall, serial CEA measurements added little to the standard clinical assessment of patients with advanced colorectal carcinoma receiving chemotherapy.