False-positive findings for tumor markers after curative gastrectomy for gastric cancer.

The objective of this study was to assess the frequency and characteristics of false-positive results for tumor markers after curative gastrectomy for gastric cancer. Carcinoembryonic antigen and/or carbohydrate antigen 19-9 were periodically assessed for 168 patients who underwent curative gastrectomy. Cancer recurrence was observed for 17 (10.1%) patients and 151 (89.9%) were disease-free during the mean follow-up period of 23.1 months after the operation. The frequency of false-positive findings for tumor markers after gastrectomy was 14.3% (24/168) for all followed-up patients. Three different patterns of marker elevation were observed in the false-positive group. A false-positive finding for these markers was observed for patients with early-stage cancer and for those with chronic benign diseases, for example bronchitis, liver dysfunction, diabetes mellitus, and renal dysfunction. For most patients with false-positive findings for a marker a spontaneous decrease in the tumor marker was observed 1-2 months after the marker was first observed at a high level after the operation. Surgeons and oncologists should therefore keep in mind the high frequency of false-positive findings for tumor markers after curative gastrectomy for gastric cancer.