Clinical value of carcinoembryonic antigen: diagnosis, prognosis, and follow-up of patients with cancer.

Plasma carcinoembryonic antigen (CEA) in nanograms per milliliter was assayed in 149 patients with benign and 567 patients with malignant disease. Elevated CEA level (greater than 5.0) was a good indicator of malignant disease but a poor screening test for cancer because of the high false-negative rate. Degree of elevation of plasma CEA level correlated with incidence of metastatic disease in patients with colorectal, gastric, and breast carcinomas, but no correlation was seen between CEA levels and status of lymph nodes in patients with localized disease. Patients with localized colorectal cancer, but elevated CEA levels before resection, had a 2.1-fold increase in the incidence of recurrence; however, this added to the prognostic value of Dukes' staging only when the CEA level remained elevated postoperatively. In 87% of patients with colorectal cancer, the CEA level was elevated at the time of recurrence, but a therapeutic value of reexploration for unexplained CEA level elevation was not confirmed.