Serial carcinoembryonic antigen (CEA) determinations in the management of metastatic breast cancer.

Serum CEA levels were determined in 2095 patients following mastectomy for breast cancer by means of a double antibody 125 I-CEA-radioimmunoassay. 91% of 1462 patients free of metastases had normal levels less than or equal to 3 ng/ml (98% less than or equal to 5 ng/ml). In contrast, 54% of 633 patients with overt metastases had raised values greater than 3 ng/ml (43% greater than 5 ng/ml). The incidence of pathological levels was dependent on tumour burden and metastatic location rising from solitary lymph node disease (6% greater than 5 ng/ml) to skin, lung, bone, liver and multiple organ involvement (60%). CEA levels correlated weakly with total alkaline phosphatase and gamma-GT activities, but not with ESR or bilirubin levels. Of 531 patients followed after surgery and who had 3-18 serial determinations in 3-51 months, 46% without metastases had normal CEA levels as did 41% of 285 patients with metastases. Of the remaining 168 patients with elevated CEA levels, most showed a correlation between rising levels and disease progression, decreasing levels with remission and persistence of fluctuating levels with stationary disease. The CEA test is recommended as a valuable adjunct to monitor the clinical response to chemo/hormo/radiotherapy in metastatic breast cancer.