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.