ASPARTIC PROTEINASES AND GASTRIN IN THE DIAGNOSIS OF GASTRIC-CANCER AND GASTRIC PRECANCEROUS CHANGES

Objective: Gastric cancer patients have been reported to have low pepsinogen I (PCA), increased pepsinogen II (PGC) levels and a reduced PGA/PGA ratio. We tested PGA, PGC and gastrin (C) levels, and the PCA/PGC ratio to verify the usefulness of these markers and of a new index (PGA x C) in the diagnosis of gastric cancer. Patients: We enrolled 51 patients with gastric cancer; 23 patients with epithelial dysplasia, 145 with chronic atrophic gastritis, 40 with gastric ulcer, 25 with duodenal ulcer, and 53 subjects lacking major or minor endoscopic and microscopic changes at gastroscopy were included as controls. Methods: PGA, PGC and gastrin levels were determined by radioimmunoassay. Statistical analysis was performed by one-way analysis of variance, the Krushkall-Wallis test, the Kolmogorov-Smirnov test, receiver operating characteristic curves and the Youden J test. Results: PGA levels and the PGA/PGC ratio were significantly reduced in gastric cancer patients (P < 0.001). No significant variations were detected in PGC or gastrin levels. The index number (PCA x G) was also clearly reduced in gastric cancer patients (P < 0.001). With a cut-off point chosen using the receiver operating characteristic curve, this 'marker' showed, in our endoscopic population, very high sensitivity (92%), specificity (94%), positive predictive value (73%) and overall accuracy (72% by the Youden J test) for cancer. Conclusions: If these results are confirmed in populations at high or very low risk, PGA x G could become a useful marker for gastric cancer.