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Background: Compliance with colonoscopy among elderly individuals participating in colorectal cancer (CRC) screening programs is unsatisfactory, despite a high detection rate of bowel‐related diseases. In this study, our aim was to analyze the impact of risk factors on the trends of compliance and detection rates in colonoscopy among high‐risk individuals aged 60–74. Methods: A retrospective study was conducted on the high‐risk individuals aged 60–74 participating in the 2021 CRC screening program in Tianjin, China. Logistic regression analyses, including both univariate and multivariate analyses, were performed to explore the impact of different risk factors on colonoscopy compliance among the high‐risk individuals. Besides, the study investigated the influence of various risk factors on the detection rates of bowel‐related diseases among the high‐risk individuals who underwent colonoscopy. Results: A total of 24,064 high‐risk individuals were included, and 5478 individuals received a free colonoscopy, with an overall compliance of 22.76%. Among them, the adenoma detection rate was 55.46%. Males and individuals with a positive FIT had high compliance and detection rates for CRC, advanced adenomas (AA), advanced colorectal neoplasia (ACN), and colorectal neoplasm (CN). Individuals aged 70–74 were associated with low compliance but high CRC, ACN, and CN detection rates. Individuals who reported a history of chronic constipation, bloody mucous, and CRC in first‐degree relative showed high compliance but no significantwere associated with the detection rates of CRC, AA, and CN. Conclusion: This study reported several risk factors associated with the screening behaviors for CRC. Patterns and trends in CRC, AA, ACN, and CN compliance and detection rates correlate with risk factors. [ABSTRACT FROM AUTHOR]

Simple Summary: 5-Fluorouracil (5-FU), in combination with various therapeutic agents, is the main strategy for patients with high risk of stage 2, and advanced stages of, human colorectal cancer. Although 5-FU-based chemotherapy causes myeloid cell suppression, which has long been considered as a major adverse effect in certain cancer patients, recent studies determined that 5-FU selectively kills myeloid-derived suppressor cells (MDSCs), to increase cytotoxic T lymphocyte activation. However, the molecular mechanism underlying 5-FU's suppression of MDSCs is incompletely understood. We report here that 5-FU activates p53, to upregulate Fas expression in MDSCs, to increase MDSC sensitivity to FasL-induced apoptosis in vitro. 5-FU therapy upregulates Fas expression, to suppress MDSC accumulation, to increase CTL tumor infiltration in tumor-bearing mice. In human colorectal cancer patients, 5-FU-based chemotherapy suppresses MDSCs and increases CTLs level. Our findings determine that the p53-Fas pathway links 5-FU to MDSC suppression. Myelosuppression is a major adverse effect of 5-fluorouracil (5-FU) chemotherapy. However, recent findings indicate that 5-FU selectively suppresses myeloid-derived suppressor cells (MDSCs), to enhance antitumor immunity in tumor-bearing mice. 5-FU-mediated myelosuppression may thus have a beneficial effect for cancer patients. The molecular mechanism underlying 5-FU's suppression of MDSCs is currently unknown. We aimed at testing the hypothesis that 5-FU suppresses MDSCs through enhancing MDSC sensitivity to Fas-mediated apoptosis. We observed that, although FasL is highly expressed in T cells, Fas is weakly expressed in myeloid cells in human colon carcinoma, indicating that downregulation of Fas is a mechanism underlying myeloid cell survival and accumulation in human colon cancer. 5-FU treatment upregulated expression of both p53 and Fas, and knocking down p53 diminished 5-FU-induced Fas expression in MDSC-like cells, in vitro. 5-FU treatment also increased MDSC-like cell sensitivity to FasL-induced apoptosis in vitro. Furthermore, we determined that 5-FU therapy increased expression of Fas on MDSCs, suppressed MDSC accumulation, and increased CTL tumor infiltration in colon tumor-bearing mice. In human colorectal cancer patients, 5-FU chemotherapy decreased MDSC accumulation and increased CTL level. Our findings determine that 5-FU chemotherapy activates the p53-Fas pathway, to suppress MDSC accumulation, to increase CTL tumor infiltration. [ABSTRACT FROM AUTHOR]