Colorectal cancer (CRC) is the third most common form of cancer, and the incidence of sporadic young-onset colorectal cancer (yCRC) has been increasing. Microbiota residing in the tumor microenvironment are emerging tumor components. The colonic microbiome differs between patients with CRC and healthy controls; however, few studies have investigated the role of the tumor microbiota in disease diagnosis and tumorigenesis of yCRC. We performed 16S rRNA sequencing analysis to identify the microbiome in CRC and found that tumor microbial diversity decreased in yCRC. Proteobacteria and Firmicutes were the most abundant phyla in all CRC samples, and Actinomyces and Schaalia cardiffensis were the key microbiota in the yCRC group. Correlation analysis revealed that Actinomyces co-occurred with various pro-tumor microbial taxa, including Bacteroidia, Gammaproteobacteria, and Pseudomonas. An independent cohort was used to validate the results. The Actinomyces in CRC was co-localized with cancer-associated fibroblasts and activated the TLR2/NF-κB pathway and reduces CD8+ T lymphocyte infiltration in CRC microenvironment. This study suggests that tumoral microbiota plays an important role in promoting tumorigenesis and therefore has potential as a promising non-invasive tool and intervention target for anti-tumor therapy.

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IntroductionThe role of tumour secretory cytokines and peripheral circulatory cytokines in tumour progression has received increasing attention; however, the role of tumour-related inflammatory cytokines in colorectal cancer (CRC) remains unclear. In this study, the concentrations of various cytokines in the peripheral blood of healthy controls and patients with CRC at different stages were compared.MethodsPeripheral blood samples from 4 healthy participants and 22 colorectal cancer patients were examined. Luminex beads were used to evaluate concentration levels of 40 inflammatory cytokines in peripheral blood samples.ResultsIn peripheral blood, compared with healthy controls and early stage (I + II) CRC patients, advanced CRC (III + IV) patients had increased concentrations of mononuclear/macrophage chemotactic-related proteins (CCL7, CCL8, CCL15, CCL2, and MIF), M2 polarization-related factors (IL-1β, IL-4), neutrophil chemotactic and N2 polarization-related cytokines (CXCL2, CXCL5, CXCL6, IL-8), dendritic cells (DCs) chemotactic-related proteins (CCL19, CCL20, and CCL21), Natural killer (NK) cell related cytokines (CXCL9, CXCL10), Th2 cell-related cytokines (CCL1, CCL11, CCL26), CXCL12, IL-2, CCL25, and CCL27, and decreased IFN-γ and CX3CL1 concentrations. The differential upregulation of cytokines in peripheral blood was mainly concentrated in CRC patients with distant metastasis and was related to the size of the primary tumour; however, there was no significant correlation between cytokine levels in peripheral blood and the propensity and mechanism of lymph node metastasis.DiscussionDifferent types of immune cells may share the same chemokine receptors and can co-localise in response to the same chemokines and exert synergistic pro-tumour or anti-tumour functions in the tumour microenvironment. Chemokines and cytokines affect tumour metastasis and prognosis and may be potential targets for treatment.

Background: Laparoscopic right colectomy (LRC) with intracorporeal ileocolic anastomosis (IIA) may be beneficial for postoperative recovery, but there is a lack of evidence to confirm this hypothesis. This study aimed to investigate the feasibility and safety of IIA.Methods: A total of 114 patients who underwent LRC with IIA (58) or extracorporeal ileocolic anastomosis (EIA, 56) between January 2019 and September 2021 were enrolled. We assessed clinical characteristics, pathological characteristics and short-term outcomes.Results: Faster gastrointestinal (GI) recovery and less postoperative pain were observed in patients with IIA than EIA [time to first flatus: (2.4±0.7) vs (2.8±1.0) days, p <0.01; time to fluid intake: (3.5±0.7) vs (4.0±1.1) days, p =0.01; visual analogue scale score on the day of surgery: (3.9±1.0) vs (4.3±0.6), p =0.02]. No significant differences were detected in oncological outcomes or postoperative complications. IIA tended to be performed in patients with higher body mass index than EIA [( 23.93±3.52) vs ( 22.36±2.87) kg/m2, p =0.01].Conclusions: IIA is associated with faster GI function recovery and less postoperative pain, and considered to be potentially superior to EIA in patients with obesity.