Abstract: OBJECTIVE To explore the variation in mammalian target of rapamycin (mTOR) signaling pathway in peripherally inserted central catheter (PICC) catheter-related bloodstream infection in cancer patients, and analyze the intervention measures of risk factors. METHODS A total of 258 cancer patients who underwent PICC in The People's Hospital of SND from Feb 2019 to Oct 2022 were retrospectively recruited. According to whether the patients had catheter-related bloodstream infection, they were divided into the infection group (n=26) and non-infection group (n=232). The clinical data of PICC catheter-related bloodstream infection in cancer patients were collected, and the infection status and pathogen distribution were analyzed. The risk factors for PICC catheter-related bloodstream infection in cancer patients were analyzed by multivariate logistic regression analysis, serum levels of phosphorylated ribosome S6 kinase 1 (p-S6K1) and phosphorylated 4E-binding protein 1 (p-4EBP1) were compared between the two groups. Receiver operating characteristic (ROC) curves were drawn to analyze the diagnostic value of serum p-mTOR, p-S6K1 and p-4EBP1 in PICC catheter-associated bloodstream infections in tumor patients. RESULTS PICC catheter-related bloodstream infection occurred in 26 of 258 tumor patients, accounting for 10.08%. A total of 28 strains of pathogenic bacteria were cultured, mainly gram-negative bacteria. Diabetes mellitus, spring and summer catheterization were independent risk factors for PICC catheter-related bloodstream infection in cancer patients (P＜0.05). Compared with the uninfected group, serum levels of P-MTOR, P-S6K1 and P-4EBP1 in the infected group were increased (P＜0.05). The area under the curve (AUC) value of the combined detection for PICC catheter-related bloodstream infection in tumor patients was higher than that of the single detection (P＜0.05), and the sensitivity and specificity of the combined detection were 96.15% and 80.60%, respectively, indicating high diagnostic value. CONCLUSION There is a high incidence of PICC catheter-associated bloodstream infection in tumor patients, and it is mainly gram-negative bacteria. Diabetes and spring and summer catheterization are risk factors for this disease, and the elevated levels of p-mTOR, p-S6K1 and p-4EBP1 lead to an increased risk of PICC catheter-associated bloodstream infection in tumor patients. The combined detection of the three indexes has a high diagnostic value for PICC catheter-associated bloodstream infection in tumor patients.