Preoperative serum TA90-IC as an adjunct to serum CA 19-9 in the diagnosis of pancreatic malignancy: A pilot study

Abstract

Purpose Because TA90, a 90-kDa immunogenic tumor-associated antigen, is expressed by pancreatic cancer cells, we hypothesized that the serum level of its immune complex with IgG (TA90-IC) might be a useful marker for diagnosis of pancreatic malignancy. We also wanted to compare TA90-IC with CA 19-9 in the diagnosis of pancreatic cancer. Methods We undertook a retrospective study of prospectively collected sera from patients with histopathologically proven pancreatic malignancies. Patient sera were analyzed for TA90-IC and CA 19-9. Sera of sex-matched and age-matched healthy volunteers (controls) were analyzed for TA90-IC. The study was conducted at a tertiary medical center. Twenty-one patients with pancreatic malignancies and 29 controls, from whom sera had been obtained and cryopreserved, were included. A positive TA90-IC level was defined as an optical density ≥ 0.410 at 405 nm following an enzyme-linked immunosorbent assay based on a murine monoclonal antibody. CA 19-9 levels were determined by immunoradiometric assay performed at outside laboratories (normal range, 0 to 37 U/mL). Results Of the 21 patients, 14 had positive TA90-IC levels and 18 had increased CA 19-9 levels (67% vs 86%; p = 0.157). The TA90-IC levels were significantly higher in the cancer group than in the control group (p = 0.0003). Of the 3 patients with normal CA 19-9 levels, 2 had positive TA90-IC levels. The combination of both markers identified 95% of patients with pancreatic malignancy, a significantly higher diagnostic rate than that of either marker alone (p = 0.014). TA90-IC sensitivity was higher for stage II and III disease than for stage IV disease (82% vs 50%). Conclusions TA90-IC assay may improve the prediction of pancreatic malignancy when used in combination with CA 19-9 levels. Because TA90-IC appears to have improved diagnostic accuracy with smaller tumor burden, the role of TA90-IC as an adjunct to CA 19-9 in screening and monitoring progression of early disease warrants further investigation.