Usefulness of serial serum carcinoembryonic antigen (CEA) determinations during anticancer therapy or long-term follow-up of gastrointestinal carcinoma.

Abstract

Repeated determinations of serum CEA levels in untreated advanced gastrointestinal cancer patients with initially elevated values showed day to day variations of ±35%. If there was no intervening chemotherapy, all such patients who were followed over long term showed progressively increasing CEA levels. With chemotherapy there was a general correlation between changes in serum CEA levels and clinically measured changes in tumor mass. Among patients who showed objective improvement, 75% had reduction in serum CEA levels (> 35%) and 87% had either reduced or unchanged levels. Among those who showed objective progression, 65% had increases in serum CEA levels (> 35%) and 80% had either increased or unchanged levels. Paradoxical reductions in CEA levels were observed in some patients approaching terminal status. Among 80 patients being followed with serial CEA determinations after potentially curative resections of large bowel cancer and normal postoperative CEA levels, 6 have again showed clinical evidence of malignant disease and in 5 of these there was concurrent elevation of serum CEA. Serial serum CEA determinations appear to have some value for following the course of gastrointestinal cancer patients after surgery or chemotherapy, but these determinations must be interpreted in the context of the over-all clinical picture.