Usefulness of serial carcinoembryonic antigen (CEA) determinations in monitoring chemotherapy

Serial carcinoembryonic antigen (CEA) levels were measured during chemotherapy for metastatic cancer in 94 patients. Criteria for chemotherapy responses were those used by the Central Oncology Group. Patients were classified according to changes in CEA levels and response to chemotherapy. Four categories represented a positive correlation: (1) increasing abnormal CEA with progressing disease, (2) decreasing abnormal CEA with disease regression, (3) unchanged abnormal CEA with stable disease, (4) change from normal to abnormal CEA with progressive disease. Positive correlation of serial CEA levels with clinical responses occurred in 71% of patients with GI cancer, 51% with breast cancer, 42% with sarcoma, 50% with respiratory cancer, and 25% with melanoma. These data indicate that serial CEA determinations may be of value as an additional parameter of response to chemotherapy in gastrointestinal cancer.