Differentiation of disease recurrence in various primary malignancies using CEA slope analysis

CEA slope analysis was performed for patients with various primary malignancies who developed recurrent disease. In 340 cases CEA slopes could be calculated, and in 289 cases correlated with distinct diagnosis of recurrent disease. Local recurrence showed a slope range of 0.02-15.2 micrograms CEA increase/l serum/10 days (median = 0.28) and metastatic spread a slope range of 0.03-456 micrograms CEA increase/l serum/10 days (median = 0.98). Subgroups of patients with metastatic spread to the liver, bone, peritoneum and other sites had distinct CEA slope distributions independent of the primary tumors. Comparable slope ranges were found with two different commercially available kits, one a radioimmunoassay (antiserum) and the other enzyme-immunoassay (monoclonal antibody).