Gut microbiota influence anastomotic healing in colorectal cancer surgery through modulation of mucosal proinflammatory cytokines.

OBJECTIVE: Colorectal cancer (CRC) is the third most diagnosed cancer, and requires surgical resection and reconnection, or anastomosis, of the remaining bowel to re-establish intestinal continuity. Anastomotic leak (AL) is a major complication that increases mortality and cancer recurrence. Our objective is to assess the causal role of gut microbiota in anastomotic healing. DESIGN: The causal role of gut microbiota was assessed in a murine AL model receiving faecal microbiota transplantation (FMT) from patients with CRC collected before surgery and who later developed or not, AL. Anastomotic healing and gut barrier integrity were assessed after surgery. Bacterial candidates implicated in anastomotic healing were identified using 16S rRNA gene sequencing and were isolated from faecal samples to be tested both in vitro and in vivo. RESULTS: Mice receiving FMT from patients that developed AL displayed poor anastomotic healing. Profiling of gut microbiota of patients and mice after FMT revealed correlations between healing parameters and the relative abundance of Alistipes onderdonkii and Parabacteroides goldsteinii. Oral supplementation with A. onderdonkii resulted in a higher rate of leaks in mice, while gavage with P. goldsteinii improved healing by exerting an anti-inflammatory effect. Patients with AL and mice receiving FMT from AL patients presented upregulation of mucosal MIP-1α, MIP-2, MCP-1 and IL-17A/F before surgery. Retrospective analysis revealed that patients with AL present higher circulating neutrophil and monocyte counts before surgery. CONCLUSION: Gut microbiota plays an important role in surgical colonic healing in patients with CRC. The impact of these findings may extend to a vast array of invasive gastrointestinal procedures.

A Canadian single-centre experience with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for abdominal malignancies.

BACKGROUND: Cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) has recently shown promise for the treatment of patients with various types of peritoneal carcinomatosis (PC). However, it is an extensive procedure that is associated with a variety of morbidities. We evaluated the safety and clinical outcomes of CRS-HIPEC performed at our centre. METHODS: Patients with abdominal malignancies who underwent CRS-HIPEC between February 2005 and December 2018 at the Centre hospitalier de l'Université de Montréal (CHUM) were retrospectively reviewed. RESULTS: A total of 141 patients were identified (66 with appendiceal cancer, 62 with colorectal cancer, 10 with mesothelioma and 3 with small intestinal tumours). The median age was 55 years. Median overall survival (OS) was not reached for patients with appendiceal tumours; it was 38.3 months for colorectal cancers. Among patients with colorectal cancer, survival was significantly better for those who received intraperitoneal HIPEC with oxaliplatin (74.9 mo) compared with mitomycin C (29.1 mo) (p = 0.006). Complete cytoreductive surgery and low peritoneal carcinomatosis index were associated with the highest overall survival in patients with appendiceal tumours and those with colorectal tumours. CONCLUSION: CRS-HIPEC can be performed with acceptable morbidity in patients with PC. These results validate the outcomes of previously reported trials, but further prospective trials are warranted to determine which patients will most benefit from the addition of HIPEC to CRS.

Splenectomy Increases Postoperative Complications Following Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

BACKGROUND: Complete cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) is increasingly performed on patients with peritoneal carcinomatosis of various origins. Splenectomy often is required in these patients to achieve complete tumor removal. Although splenectomy has been associated with increased morbidity in many major abdominal surgeries, its effect in patients undergoing CRS + HIPEC is unknown. The purpose of this study was to evaluate the impact of splenectomy during CRS + HIPEC on postoperative outcomes. METHODS: We retrospectively identified 39 patients who underwent CRS + HIPEC with splenectomy during a 3-year study period from a prospective database. We compared them to case controls (CRS + HIPEC without splenectomy) that were matched for the complexity of the procedure. We evaluated the complication rate and outcomes of patients in each group. RESULTS: During the study period, splenectomy was performed in 32 % of patients undergoing CRS + HIPEC procedure. Patients in the splenectomy group experienced more grade 3-4 complications than patients in the control group (59 vs. 35.9 %, p = 0.041) as well as more pulmonary complications (41 vs. 7.7 %, p = 0.0006). Multivariate analysis identified splenectomy as the only predictor of overall major complications (odds ratio = 2.57, 95 % confidence interval = 1.03-6.40). Mortality was similar in both groups. CONCLUSIONS: Splenectomy increases major complication rate in patients undergoing CRS + HIPEC and efforts should be made to preserve the spleen during the surgery.

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.

Current evidence on the relation between gut microbiota and intestinal anastomotic leak in colorectal surgery.

BACKGROUND: Anastomotic leak (AL) is a major complication in colorectal surgery. It worsens morbidity, mortality and oncological outcomes in colorectal cancer. Some evidence suggests a potential effect of the intestinal microbiome on wound healing. This review aims to provide a comprehensive review on historical and current evidence regarding the relation between the gastrointestinal microbiota and AL in colorectal surgery, and the potential microbiota-modifying effect of some perioperative commonly used measures. DATA SOURCES: A comprehensive search was conducted in Pubmed, Medline and Embase for historical and current clinical and animal studies addressing perioperative intestinal microbiota evaluation, intestinal healing and AL. CONCLUSIONS: Evidence on microbes' role in AL is mainly derived from animal experiments. The microbiota's composition and implications are poorly understood in surgical patients. Elaborate microbiota sequencing is required in colorectal surgery to identify potentially beneficial microbial profiles that could lead to specific perioperative microbiome-altering measures and improve surgical and oncological outcomes.

No clinical benefit from routine histologic examination of stapler doughnuts at low anterior resection for rectal cancer.

BACKGROUND: The aim of this study was to evaluate the clinical utility and cost-effectiveness of routine histologic examination of the doughnuts from stapled anastomoses in patients undergoing a low anterior resection for rectal cancer. METHODS: We performed a retrospective review of 486 patients who underwent a low anterior resection with stapled anastomosis for rectal cancer between 2002 and 2015 at 3 institutions. Pathologic findings in the doughnuts and their impact on patient management were recorded. Tumor characteristics that may influence how often doughnuts were included in the pathology report were analyzed. An approximate cost of histologic examination of doughnuts was also calculated. RESULTS: A total of 412 patients (85%) had doughnuts included in their pathology reports. Two patients had cancer cells in their doughnuts, and both patients had a positive distal margin in their primary tumor specimen; 33 patients had benign findings in their doughnuts. Pathologic examination of the doughnut did not change clinical management in any patient. Patients with rectosigmoid tumors were less likely to have their doughnuts included in the pathology report compared to patients with low tumors (P = .003). Doughnuts were not bundled with the primary tumor specimen in 374 (77%) of our patients; in these patients, pathologic analysis of the doughnut added an additional cost of approximately $643 per specimen. CONCLUSION: This study demonstrates no clinical benefit in sending anastomotic doughnuts for histopathologic evaluation after performing a low anterior resection with a stapled anastomosis for rectal cancer. Overall cost may be decreased if doughnuts are not analyzed or if they are bundled with the primary tumor specimen.