[Clinical usefulness of tumor markers associated with pancreatic cancer]

Abstract

Most of the recently developed tumor antigens detected by monoclonal antibodies are sugar chains and frequently associated with blood group substance. By immunohistochemical studies, we evaluated mainly the clinical usefulness and significance of the serum assay of CA-50 classified as a type 1 sugar chain, sialyl SSEA-1 as a type 2 sugar chain, and ST-439 with an undetermined structure, as well as their clinicopathological significance. In addition, the value of measurement of CA19-9, ST-439, and SLX in pure pancreatic juice (PPJ) was investigated. Furthermore, the clinical usefulness of K-ras mutation at codon 12 (KRM) in PPJ was studied. The incidence of serum CA19-9 among tumor markers was highest in pancreatic cancer (81%), but relatively high in benign diseases. On the other hand, both serological and immunohistological studies showed that sialyl SSEA-1 and ST-439 were highly specific for the tumor, whereas they appeared in serum or tumor less frequently than CA19-9 or CA-50 carrying the type 1 sugar chain. The accuracy of the tumor markers (CA19-9, sialyl SSEA-1, and ST-439) for pancreatic cancer, was almost equal (77% to 80%) and higher than that of CEA (69%). However, a highly positive correlation between sialyl SSEA-1 and ST-439 was revealed as well as among type 1 sugar chains in malignant diseases. Therefore, we conclude that the combination assay with CA19-9 or a similar tumor marker, sialyl SSEA-1 or ST-439, and CEA would be appropriate for the screening of pancreatic cancer. When the cut off value was set as the M + 2SD of the controls, significantly elevated concentrations of CA19-9 in PPJ were found in the secretory phase in 90% of the patients with pancreatic cancer (PC) and 66% of the patients with chronic pancreatitis (CP). Although increased concentrations of CA19-9 in PPJ have no cancer specificity, measurement of CA19-9 in PPJ can be used as a sensitive marker for some pancreatic disorders. On the other hand, concentrations of ST-439 and SLX in PPJ were significantly increased only in PC, and their incidences were 50% and 40%, respectively. They have a high tumor-specificity, but their incidences were not as high as initially expected.(ABSTRACT TRUNCATED AT 400 WORDS)