Circulating carcinoembryonic antigen (CEA), a growth parameter in malignant disease.

In a series of experiments we measured tumor volume or tumor mass together with the serum CEA concentration in human adenocarcinoma-bearing nude mice. We observed a linear relationship between log CEA and time over a period of up to 30 days after transplantation of the tumors. In all experiments tumor mass-volume correlated well with concomitant increase of the circulating CEA concentration. A marked dissociation became evident when tumor growth rate slowed down. At that time histologic investigations indicated that necrosis of the tumor could be a potential factor for this phenomenon. A retrospective analysis of the CEA time courses in 114 patients with recurrent colorectal cancer gave evidence for similar CEA developments in 87 cases also exhibiting linear log CEA development with time. Individual CEA doubling times calculated from linear log CEA increases correlated well with observed survival in 36 patients with untreated visceral metastasis. Moreover, the CEA doubling time represented an objective parameter to rate the effect of various postoperative therapies when survival is expressed in multiples of individual CEA doubling times.