Can biliary carcinoembryonic antigen identify colorectal cancer patients with occult hepatic metastases?

Twenty-five percent of radically treated colorectal cancer patients already have occult hepatic metastases (OHM) that will later be observed during postoperative follow-up. Instrumental examinations, i.e., intraoperative ultrasound or Doppler perfusion index, have not improved diagnosis. As carcinoembyonic antigen (CEA) levels are useful to reveal hepatic metastases from colorectal cancer, determination of CEA in the bile rather than the blood may allow preclinical diagnosis of OHM thanks to the reduced volume of bile.

One hundred radically treated colorectal cancer patients were enrolled in the study. Bile was withdrawn from the gallbladder intraoperatively and biliary CEA levels determined using an immuno-enzymatic method (normal value 0-5 ng/ml). Eighty-nine fully evaluable patients were followed up for three years postoperatively to monitor hepatic metastases. Preoperative blood CEA, lymph node metastases and biliary CEA were compared in order to assess which procedure was more efficient in identifying patients who would develop hepatic metastases.

Eleven of the 89 evaluable patients developed hepatic metastases: 9/11 presented elevated biliary CEA levels (mean: 12.73; range: 5.1-26.2); 8/11 had high preoperative blood CEA values; and 9/11 were at anatomopathological stage N+. In the 78 patients who did not develop hepatic metastases, biliary CEA was within normal limits in 73/78, preoperative blood CEA was normal in 60/78, and 58/78 patients were at anatomopathological stage N-. Hence, the sensitivity of biliary CEA was 81.8%, specificity was 93.6%, and diagnostic accuracy was 92.1%.

Determination of biliary CEA seems to be more efficient in identifying patients presenting OHM who require frequent clinical examinations or adjuvant cancer treatment.