title: TA90-IC, a new marker for advanced colon cancer.
abstract: BACKGROUND
  Although carcinoembryonic antigen (CEA) is the most frequently used marker for colon cancer, it is elevated in only 70% of patients with advanced disease and in even fewer patients with earlier stages of disease. We previously identified a 90-kDa glycoprotein, TA90, which is present in serum in the form of circulating immune complexes. TA90 is found in a variety of solid neoplasms but rarely in healthy controls (3.2%). We hypothesized that this new tumor-associated antigen may be a useful marker for colon cancer.
  
  
  METHODS
  Serum samples from 59 patients with known colon adenocarcinoma were analyzed for the presence of CEA and TA90. Fifty-one (86%) patients had distant metastases; the remaining patients had clinically localized primary colon cancer. A murine monoclonal antibody-based enzyme-linked immunosorbent assay was used to measure concentrations of TA90-specific circulating immune complexes (TA90-IC). A positive value was defined as an optical density of more than 0.410 at 405 nm. Forty-seven (80%) of the 59 patients had serum samples for TA90 and CEA drawn at the same time.
  
  
  RESULTS
  TA90-IC concentrations were elevated more frequently than CEA concentrations (82.9% vs. 70.2%; P = .134). The combination of both markers identified more patients with colon carcinoma than did either marker alone (93.6%; P < .001).
  
  
  CONCLUSIONS
  Concomitant use of TA90-IC and CEA identified 93.6% of patients with advanced colon cancer. The role of TA90-IC in screening and monitoring progression of earlier disease deserves further investigation.
authors.affiliation: Roy E. Coats Research Laboratories, John Wayne Cancer Institute at St. John's Health Center, Santa Monica, California 90404, USA.
authors.forename: N
authors.initials: N
authors.lastname: Habal
authors.forename: R K
authors.initials: RK
authors.lastname: Gupta
authors.forename: A J
authors.initials: AJ
authors.lastname: Bilchik
authors.forename: T
authors.initials: T
authors.lastname: Johnson
authors.forename: D L
authors.initials: DL
authors.lastname: Morton
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D002272:Carcinoembryonic Antigen / Q000032:analysis; D003110:Colonic Neoplasms / Q000145:classification / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; C113885:TA90 immune complex