title: Clinical significance of serum RCAS1 levels detected by monoclonal antibody 22-1-1 in patients with cholangiocellular carcinoma.
abstract: OBJECTIVE
  The tumor-associated antigen, RCAS1, has been reported to be expressed in various types of cancer, including cholangiocarcinoma. We measured serum RCAS1 levels in patients with intrahepatic cholangiocellular carcinoma (CCC) and other hepatobiliary diseases, and examined the clinical significance of serum RCAS1 as a tumor marker.
  
  
  METHODS
  Sera collected from the patients and healthy volunteers were used for ELISA for RCAS1. The values of RCAS1 for CCC patients were compared to those of other tumor marker proteins.
  
  
  RESULTS
  Serum RCAS1 levels exceeded the normal limit in a high percentage (73.9%) of CCC patients. The positivity rate was higher than those of CA19-9 and CEA. No correlation was found between the RCAS1 and CA19-9 concentrations. Serum RCAS1 was positive in many cases that were negative for CA19-9. Surgical resection of CCC reduced the RCAS1 level to within the normal range. On the other hand, serum RCAS1 levels were elevated in very few cases of benign hepatobiliary disease.
  
  
  CONCLUSIONS
  As a tumor marker in CCC, RCAS1 is, at least, of complementary value to CA19-9 and CEA. Measuring serum RCAS1 contributes to the diagnostic accuracy, and is useful for estimating tumor progression or therapeutic effect.
authors.affiliation: Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Watanabe
authors.forename: Munechika
authors.initials: M
authors.lastname: Enjoji
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakashima
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Noguchi
authors.forename: Naoko
authors.initials: N
authors.lastname: Kinukawa
authors.forename: Rie
authors.initials: R
authors.lastname: Sugimoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kotoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamuta
authors.forename: Hajime
authors.initials: H
authors.lastname: Nawata
authors.forename: Takeshi
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000097:blood*; D001650:Bile Duct Neoplasms / Q000097:blood / Q000276:immunology* / Q000601:surgery; D001653:Bile Ducts, Intrahepatic / Q000601:surgery; D018395:CA-19-9 Antigen / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D018281:Cholangiocarcinoma / Q000097:blood / Q000276:immunology* / Q000601:surgery; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D018395:CA-19-9 Antigen; D002272:Carcinoembryonic Antigen; C120762:EBAG9 protein, human