Modulating Gut Microbiota Prevents Anastomotic Leak to Reduce Local Implantation and Dissemination of Colorectal Cancer Cells after Surgery.

PURPOSE: Anastomotic leak (AL) is a major complication in colorectal cancer surgery and consists of the leakage of intestinal content through a poorly healed colonic wound. Colorectal cancer recurrence after surgery is a major determinant of survival. We hypothesize that AL may allow cancer cells to escape the gut and lead to cancer recurrence and that improving anastomotic healing may prevent local implantation and metastatic dissemination of cancer cells. EXPERIMENTAL DESIGN: We investigated the association between AL and postoperative outcomes in patients with colorectal cancer. Using mouse models of poor anastomotic healing, we assessed the processes of local implantation and dissemination of cancer cells. The effect of dietary supplementation with inulin and 5-aminosalicylate (5-ASA), which activate PPAR-γ in the gut, on local anastomotic tumors was assessed in mice undergoing colonic surgery. Inulin and 5-ASA were also assessed in a mouse model of liver metastasis. RESULTS: Patients experiencing AL displayed lower overall and oncologic survival than non-AL patients. Poor anastomotic healing in mice led to larger anastomotic and peritoneal tumors. The microbiota of patients with AL displays a lower capacity to activate the antineoplastic PPAR-γ in the gut. Modulation of gut microbiota using dietary inulin and 5-ASA reinforced the gut barrier and prevented anastomotic tumors and metastatic spread in mice. CONCLUSIONS: Our findings reinforce the hypothesis that preventing AL is paramount to improving oncologic outcomes after colorectal cancer surgery. Furthermore, they pave the way toward dietary targeting of PPAR-γ as a novel way to enhance healing and diminish cancer recurrence.

Putrescine supplementation limits the expansion of pks+ Escherichia coli and tumor development in the colon.

Escherichia coli that harbor the polyketide synthase (pks) genomic island produce colibactin and are associated with sporadic colorectal cancer development (CRC). Given the considerable prevalence of pks+ bacteria in healthy individuals, we sought to identify strategies to limit the growth and expansion of pks+ E. coli. We found that culture supernatants of the probiotic strain E. coli Nissle 1917 were able to inhibit the growth of the murine pathogenic strain pks+ E. coli NC101 (EcNC101). We performed a non-targeted analysis of the metabolome in supernatants from several E. coli strains and identified putrescine as a potential postbiotic capable of suppressing EcNC101 growth in vitro. The effect of putrescine supplementation was then evaluated in the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of CRC in mice colonized with EcNC101. Putrescine supplementation inhibited the growth of pks+ E. coli; reduced the number and size of colonic tumors; and downmodulated the release of inflammatory cytokines in the colonic lumen. Additionally, putrescine supplementation led to shifts in the composition and function of gut microbiota, characterized by an increase of the Firmicutes/Bacteroidetes ratio and enhanced acetate production. The effect of putrescine was further confirmed in vitro using a pks+ E. coli strain isolated from a CRC patient. These results suggest that probiotic-derived metabolites can be used as an alternative to live bacteria in individuals at risk of developing CRC due to the presence of pks+ bacteria in their colon.

Safety and clinical efficacy of EUS-guided pelvic abscess drainage.

Background and Objectives: EUS is a potential alternative for the drainage of abscesses. The aim of this study was to determine if EUS-guided pelvic abscess drainage is technically feasible, safe, and a valid option for abscess resolution. Methods: We conducted a retrospective review from 2002 to 2020 at a single quaternary institution. EUS-guided pelvic abscess drainage via the transrectal route was performed in all patients with or without drain/stent placement. Technical and clinical success of EUS-guided pelvic abscess drainage was analyzed. Descriptive analyses and Fisher exact test were performed. Results: Sixty consecutive patients were included in the study (53.5% male; mean age, 53.8 ± 17.9 years). Pelvic abscesses occurred mainly postoperatively (33 cases; 60.0%) and from complicated diverticulitis (14 cases; 23.3%). Mean diameter was 6.5 ± 2.4 cm (80% unilocular). Drainage was performed with EUS-guided stent placement (double-pigtail plastic or lumen-apposing metal) in 74.5% of cases and with aspiration alone for the remainder. Technical success occurred in 58 cases (97%). Of those with long-term follow-up after EUS-guided pelvic abscess drainage (n = 55; 91.7%), complete abscess resolution occurred in 72.7% of all cases. Recurrence occurred in 8 cases (14.5%) and persisted in 7 patients (12.5%), 7 of which were successfully retreated with EUS-guided pelvic abscess drainage. Accounting for these successful reinterventions, the overall rate of abscess resolution was 85.5%. Abscess resolution rate improved with drain placement (83%). Accounting for 7 repeat EUS-guided pelvic abscess drainages, overall abscess resolution improved. Two deaths occurred (3.4%) because of sepsis from failed source control in patients who had previously failed medical, radiological, and surgical treatment. Conclusions: EUS-guided pelvic abscess drainage is technically feasible, safe, and an effective alternative to radiological or open surgical drainage. It also offers favorable clinical outcomes in different clinical situations.

Prevalence of pks + bacteria and enterotoxigenic Bacteroides fragilis in patients with colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is the third most diagnosed cancer and the second most common cause of cancer deaths worldwide. CRC patients present with an increase in pathogens in their gut microbiota, such as polyketide synthase-positive bacteria (pks +) and enterotoxigenic Bacteroides fragilis (ETBF). The pks + Escherichia coli promotes carcinogenesis and facilitates CRC progression through the production of colibactin, a genotoxin that induces double-strand DNA breaks (DSBs). ETBF is a procarcinogenic bacterium producing the B. fragilis toxin (bft) that promotes colorectal carcinogenesis by modulating the mucosal immune response and inducing epithelial cell changes. METHODS: Fecal samples were collected from healthy controls (N = 62) and CRC patients (N = 94) from the province of Québec (Canada), and a bacterial DNA extraction was performed. Fecal DNA samples were then examined for the presence of the pks island gene and bft using conventional qualitative PCR. RESULTS: We found that a high proportion of healthy controls are colonized by pks + bacteria (42%) and that these levels were similar in CRC patients (46%). bft was detected in 21% of healthy controls and 32% of CRC patients, while double colonization by both pks + bacteria and ETBF occurred in 8% of the healthy controls and 13% of the CRC patients. Most importantly, we found that early-onset CRC (< 50 years) patients were significantly less colonized with pks + bacteria (20%) compared to late-onset CRC patients (52%). CONCLUSIONS: Healthy controls had similar levels of pks + bacteria and ETBF colonization as CRC patients, and their elevated levels may place both groups at greater risk of developing CRC. Colonization with pks + bacteria was less prevalent in early-compared to late-onset CRC.

Three colonic cancers, two sites of complete occlusion, one patient: A case report.

BACKGROUND: Synchronous colonic cancer incidence is uncommon, and awareness about this rare condition is improved recently. However, in the presence of acute colonic obstruction, investigation and management of synchronous colonic cancer can be difficult and challenging. CASE SUMMARY: A patient presented with acute colonic obstruction with impending rupture and complete examination of this patient revealed the presence of three colonic cancers, of which two were completely occluding. CONCLUSION: The presence of multiple colonic cancers must be ruled out in order to plan the best management. We present the case with a review of literature and discuss the management of the case.