Serum levels of CA 50 in nonmalignant liver diseases: a clinical and biochemical study.

CA 50 is a tumor marker used in the evaluation and follow-up of some cancers, especially of the digestive tract. However, CA 50 frequently produces false-positive results, particularly in pancreatic and hepatobiliary diseases. This study was carried out to evaluate the behavior of CA 50 in 159 patients with benign diffuse liver diseases, who underwent a thorough clinical and laboratory evaluation. There were abnormal levels of CA 50 in 56% of the 159 patients, and in 75.3% of the 85 cirrhotics, with very high values in some cases. We found significant correlations between CA 50 and some clinical and biochemical parameters. Significantly higher levels of CA 50 were found in cirrhotics than in noncirrhotics (p < 0.0001), and in hyperbilirubinemic patients than in those with normal bilirubin (p < 0.0001). Several mechanisms, including liver dysfunction and pathological changes of the smallest bile ducts, probably are responsible for the increase in CA 50. Several cut-offs for different subsets of patients, according to the diagnosis and level of bilirubin, have been calculated. Whenever CA 50 is used in the evaluation of a cancer patient, a benign liver disease should be excluded, because the liver disorder can result in increased serum levels of CA 50, independent of cancer.