Plasma clearance of carcinoembryonic antigen following hepatic metastatectomy

Four patients with isolated hepatic metastases from primary colonic cancer presented with elevated plasma carcinoembryonic antigen (CEA) levels and underwent surgical metastatectomy . Plasma levels were monitored at two to six hour intervals in the immediate postoperative period and daily measurements were obtained for an extended period thereafter, up to 34 days. CEA clearance demonstrated a two-phase decrement with an initial rapid decay followed by a logarithmic decline with plasma half-lives of 66, 75, 150, and 208 hours. The first phase decline of 63% to 89% in circulating CEA levels immediately following tumor removal may reflect the fact that the plasma CEA is in dynamic equilibrium with the tumor CEA. The kinetics of the second-phase decline of CEA is variable and may be related to the quantitative circulating pool or to pathophysiologic processes influencing CEA metabolism or secretion in the liver. Quantitative assessment of tumor CEA content by immunoperoxidase techniques suggests a direct relationship between tissue levels and circulating plasma levels. The study of CEA kinetics may help in understanding the biology of tumor marker production and improve the capacity for clinical monitoring of plasma levels in conjunction with tumor therapy.