Blood group A, B, H, Le, Leb, Lex, and Ley antigenicity as well as the 
expression of CA 19-9 were examined in pancreatic cancer specimens from 30 
patients, using monoclonal antibodies to the respective antigen and 
immunohistochemical techniques, and the findings were correlated with the blood 
group types (ABO and Lewis) of the individuals. Compatible antigen expression 
was found in 82, 75, and 50% of tumors from patients with A, B, and O blood 
group types, respectively. Deletion of the compatible antigen was found in 10 
(33%) of the cases, predominantly in patients of blood group O type, and 
incompatible expression (of B antigen only) in 4 (13%). Lea was detected in 87%, 
Leb in 90%, Lex in 30%, and Ley in 43% of the specimens, regardless of ABH and 
Lewis phenotype of the patients. Coexpression of Lea and Leb was found in 87%, 
of Lex and Ley in 13%, of Lea and Lex in 23%, and of Leb and Ley in 40% of the 
cases. CA 19-9 was expressed in 80% of the tumors; it was present in the tumor 
tissue of 21 of 22 patients from Lea-b+, in all 4 individuals from Lea+b-, but 
in none of the 4 patients from Lea-b- phenotype (P less than 0.01). 
Heterogeneity in the expression of each of the antigens was found. The overall 
results indicate that blood group antigen expression in pancreatic tumor differs 
from that of other gastrointestinal cancers and that the Lewis antigen 
expression in pancreatic cancer cells is independent of the blood group 
phenotype of the patients and thus may be useful as a tumor marker.