The presence of HAMA in patients can cause false-positive or false-negative results with tests for the determination of blood CEA levels. Approximately 5% of colorectal cancers are not associated with increased levels of CEA. CEA may be elevated in many types of solid cancer.
Increased serum CEA levels have been detected in persons with primary colorectal cancer and in patients with other malignancies involving the gastrointestinal tract, breast, lung, ovarian, prostatic, liver and pancreatic cancers. Elevated serum CEA levels have also been detected in patients with nonmalignant disease, especially patients who are older or who are smokers. CEA levels are not useful in screening the general population for undetected cancers. However, CEA levels provide important information about patient prognosis, recurrence of tumors after surgical removal, and effectiveness of therapy.