Abstract: Objective To analyze the influencing factors of Helicobacter pylori (Hp) infection in gastric stump after gastric cancer surgery by combining regulatory T cells (Treg) and T helper cells (Th17), and to construct a nomogram prediction model of Hp infection in gastric stump after gastric cancer surgery. 
Methods The clinical data of 80 patients with gastric cancer treated in the First Central Hospital of Baoding City were included. All patients underwent gastrectomy, and were divided into infection group (n=18) and non-infection group (n=62) according to presence of Hp infection after gastric cancer surgery. The clinical data of patients were collected and analyzed retrospectively. Logistic regression analysis was used to determine the influencing factors related to Treg and Th17 cytokines in patients with Hp infection after gastric cancer surgery. The nomogram prediction model of Hp infection after gastric cancer surgery was constructed by Treg/Th17 cytokines. The effectiveness of the nomogram prediction model was evaluated from three dimensions: C index, receiveroperating characteristic (ROC) curve and calibration curve. 
Results Comparing the clinical data of two groups, there was no significant difference in patient age, body mass index (BMI), gender, clinical stage, and location of onset (P＞0.05). The level of IL-17 in the infection group was ［(4.76±0.88) ng/L］, which was higher than that in the non-infection group ［(3.78±0.94) ng/L］, and the level of IL-21 was 〖JP2〗［(3.71±0.76) pg/L］, which was higher than that in the non-infection group ［(3.24±0.81) pg/L］. The level of Th17 was ［(3.07±0.53)%］, which was higher than that in the non-infection group ［(2.71±0.64)%］, and the level of IL-10 in the infection group was ［(8.15±3.39) ng/L］, which was lower than that in the non-infection group ［(10.47±3.67) ng/L］. The level of Treg was ［(2.59±0.61)%］, which was lower than that of the non-infection group ［(3.09±0.52)%］, and the difference was statistically significant (P＜0.05). The results of logistic regression analysis showed that IL-17, IL-21, and Th17 were the influencing factors of Hp infection after gastric cancer surgery (OR＞1, P＜0.05), while IL-10 and Treg were the protective factors of Hp infection after gastric cancer surgery (OR＜1, P＜0.05). ROC curves were drawn using the determined influencing factors, and the curve results showed that the area under the ROC curve (AUC) values of IL-17, IL-21, Th17, IL-10, and Treg were all greater than 0.60, indicating that the above indicators provided value for predicting Hp infection after gastric cancer surgery. Using the above influencing factors to establish a nomogram risk model, the verification results showed that the C-index value of the calibration curve was 0.904, indicating that the nomogram model had good predictive effectiveness. 
Conclusion The probability of Hp infection in gastric stump after gastric cancer surgery can be directly predicted by constructing a nomogram prediction model based on Treg/Th17 cytokines for Hp infection in the gastric stump after gastric cancer surgery.

Key words: Gastricneoplasms, gastrectomy, helicobacter pylori infection