The influence of cholestasis on CA 50 and CA 242 in pancreatic cancer and benign biliopancreatic diseases.

The tumour markers CA 50 and CA 242 were determined in serum from 70 cholestatic patients--35 with pancreatic cancer and 35 with benign biliopancreatic diseases. Both markers correlated (r = 0.37) with serum bilirubin in all patients. When the patients were subdivided into groups, the only correlation apparent was between CA 50 and bilirubin in patients with benign diseases (r = 0.40). The serum concentrations of both markers were much higher in patients with pancreatic cancer. Serial sampling before and after decompression of the cholestasis showed reduction of CA 50 and CA 242 concurrently with bilirubin and alkaline phosphatases in nine patients with benign disease but unchanged levels in six cancer patients. When the two markers were compared, sensitivity was superior for CA 50 (94% versus 73%), whereas specificity was better for CA 242 (65% versus 34%), as was positive prediction (76% versus 59%), whereas negative prediction was higher for CA 50 (86% versus 61%). Higher cut-off levels yielded better specificity for CA 50 but not for CA 242. Both markers indicate pancreatic cancer irrespective of cholestasis, but moderate elevations occur in some patients with benign disorders.