Analysis of cathepsin S expression in gastric adenocarcinoma and in Helicobacter pylori infection

Recent experimental studies have suggested a potential link between cathepsin S (CTTS) and gastric adenocarcinoma progression. Herein, we aimed to evaluate the expression of CTTS in gastric adenocarcinoma in patients who underwent curative-intent surgical resection. This was a cross-sectional study that included two groups: gastric adenocarcinoma (n = 42) and gastritis (n = 50). The gastritis group was then subdivided into H. pylori-positive (n = 25) and H. pylori-negative (n = 25) groups. Gastric tissue samples were analysed to determine CTTS expression through immunohistochemistry. Samples were obtained by oesophagogastroduodenoscopy or surgical specimens. In patients with gastritis, the age ranged from 18 to 78 years. Among them, 34% were male, and 66% were female. In patients with gastric adenocarcinoma, the age ranged from 37 to 85 years. Among them, 50% were male. When comparing the expression of CTTS between the two groups, only 16% of the gastritis samples had an expression higher than 25%. Alternatively, among patients with gastric adenocarcinoma, 19% had expression between 25-50%, 14.3% between 51-75%, and 26.2% had expression higher than 75% (p < 0.001). In the gastritis group, CTTS expression was significantly higher in patients with a positive test for H. pylori than negative test for H. pylori: 87.5% and 38.5%, respectively (p