Evaluation of serum amyloid A as a biomarker for gastric cancer

Background: Serum amyloid A (SAA) is a useful biomarker for gastric cancer in an animal model. We investigated the potential of SAA as a biomarker for gastric cancer in humans. Methods: Serum levels of SAA from 96 gastric cancer patients were measured before and after curative gastrectomy; 32 patients with gastric ulcers and 52 healthy subjects were the control groups. The immunohistochemical study was performed to evaluate the protein expression over gastric cancer tissue slides. Results: The mean SAA concentration was higher in gastric cancer patients (88.54 +/- 50.44 mg/l) than in healthy subjects (3.36 +/- 2.29 mg/l) and gastric ulcer patients (10.48 +/- 8.97 mg/l) (P < .05). The SAA concentration was associated with tumor stage (P = .0244) and location (P = .0016) but not with Lauren's histological type (P = .839). In the multivariate analysis, SAA level was correlated with tumor location (P < .0001) and lymph node status (P < .05). During follow-up, the mean SAA concentration increased significantly in 24 patients with tumor recurrence (P < .05) but did not change in 77 patients without recurrence. In the survival analysis, patients with SAA levels > 97 mg/l had a nearly fourfold increase in risk of death. Immunoreactivity was most prominent in blood vessel regions but not within cancer cells. Conclusions: These data not only demonstrated SAA was useful in predicting survival of patients with gastric cancer, but they also showed that SAA was a valuable tool for postoperative follow-up.