The detection of human pancreatic cancer-associated antigen in the serum of cancer patients.

A radioimmunoassay (RIA) test for human pancreatic cancer-associated antigen (Span-1) was developed to evaluate the diagnosis of various gastrointestinal disorders. Serum Span-1 in normal subjects ranged from 5 to 275 U/ml, with a mean of 58.8 U/ml (+/- 58.7, standard deviation). All control subjects had levels of less than 400 U/ml. Study subjects, 93% with pancreatic cancer, 59% with hepatobiliary cancers, 23% with gastric cancers, and 13% with colonic cancers had serum Span-1 levels greater than 400 U/ml. Sensitivities of Span-1, CA 19-9, and Dupan-2 for pancreatic cancer were 94%, 85%, and 38% respectively. Span-1 in patients with Stage I pancreatic cancer showed a 50% positive rating but CA 19-9 and Dupan-2 showed only 0% and 25%. Although a positive rating of these three antibodies increased in advanced cases, Span-1 showed the highest positive rating. Span-1 reacted with colonic cancer tissues with Lewisa-b- phenotype. However, none of these tissues did not react against CA 19-9. From these results, Span-1 has a good predictive value for detecting pancreatic cancer compared with CA 19-9 and Dupan-2.