COMPARATIVE-STUDY OF CA242 AND CA19-9 FOR THE DIAGNOSIS OF PANCREATIC-CANCER

A comparative study of a new tumour marker, CA242, and CA19-9 was cond ucted with special reference to their diagnostic usefulness in pancrea tic cancer. CA242 showed sensitivity similar to that of CA19-9 for ove rall cases and early cases (stage I tumour) of pancreatic cancer. For other malignancies, the positive rates of CA242 were lower than those of CA19-9 except for colorectal cancer. An important characteristic of CA242 was that it was only slightly and infrequently elevated in the sera of patients with benign diseases such as chronic pancreatitis, ch ronic hepatitis and liver cirrhosis. This characteristic was more appa rent in the patients with benign obstructive jaundice, indicating that the serum level of this marker was scarcely affected by cholestasis. Using cut-off levels corresponding to a 90% specificity, the clinical results obtained with CA242 in the diagnosis of pancreatic cancer were similar to those obtained with CA19-9, except that CA19-9 was falsely negative in some patients with early-stage pancreatic cancer. These f indings suggest the usefulness of this marker for screening pancreatic cancer in patients on their first hospital visit. However, CA242 was found to be influenced by the Lewis blood group system. This unfavoura ble result is attributed to the C241 catcher antibody of this assay sy stem, which has almost the same epitope specificity as the C50 and the NS19-9 monoclonal antibodies. In conclusion, CA242 is superior to CA1 9-9 in diagnosing pancreatic cancer by virtue of its higher specificit y.