Colon and Rectal Cancer Management in Low-Resource Settings.

Colorectal cancer (CRC) incidence is rising in low- and middle-income countries, which also face disproportionate mortality from CRC, mainly due to diagnosis at late stages. Various challenges to CRC care exist at multiple societal levels in underserved populations. In this article, barriers to CRC care, strategies for screening, and treatment in resource-limited settings, and future directions are discussed within a global context.

Role of biliary stent and neoadjuvant chemotherapy in the pancreatic tumor microbiome.

BACKGROUND: Intra-tumor microbiota have been implicated in pancreatic ductal adenocarcinoma (PDAC) development, treatment response and post-treatment survivorship. Moreover, therapeutic interventions targeting microbiota may improve the response to chemotherapy and immunotherapy, further emphasizing the critical need to understand the origins of and growth of bacteria within the pancreatic tumor microenvironment. Here, we studied the role of several clinical factors on the bacterial colonization of PDAC. RESULTS: We obtained matched tumor and normal pancreatic tissue specimens from 27 patients who had undergone surgical resection for PDAC between 2011 and 2015 from the University of Minnesota Biological Materials Procurement Network (BioNet). We found that 26 (48%) out of 54 pancreatic tissue samples harbored detectable bacterial communities using real-time PCR targeting the 16S rRNA gene. Bacterial colonization was detected significantly more frequently in samples from patients who had pancreatic head tumors, underwent Whipple procedure, or had preoperative biliary stent placement. There was also a significantly greater relative abundance of microbiota from the family Enterobacteriaceae among samples from patients who underwent biliary stent placement or neoadjuvant treatment with a combination of Gemcitabine and Paclitaxel. CONCLUSIONS: These findings suggest that biliary stent placement and neoadjuvant chemotherapy are associated with specific alterations that promote the infiltration and growth of intra-tumor bacteria in the setting of PDAC. Further studies exploring whether specific bacterial communities could contribute to increased chemoresistance will be essential for optimizing medical therapies in the future.

Incidence and predictors of incisional hernia after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

Background and objectives: The incidence of incisional hernia (IH) after cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is largely unknown. Methods: We conducted a retrospective study to identify patients who underwent CRS/HIPEC from 2001 to 2016. Patients were followed postoperatively for a minimum of two years. The primary outcome was the occurrence of an IH identified either on CT scan or physical examination. Univariate and multivariable logistic regression models were used to test associations with IH. Results: We identified 155 patients who underwent CRS/HIPEC; 26 patients (17%) were diagnosed with an IH at a median time of 245 days (Interquartile range [IQR] 175 - 331 days). On multivariable analysis, older age [50-64 vs. 18-49 years: hazard ratio (HR) = 0.08; 95% confidence interval (CI), 0.01 to 0.64)], female gender (HR = 0.09; 95% CI, 0.01 to 0.75), and increased BMI (>30 vs. <25; HR = 0.03; 95% CI, 0.01 to 0.37) were significant independent predictors of IH. Conclusions: The incidence of IH in this high-risk patient population treated with CRS/HIPEC is similar to that after other abdominal cancer operations. Nevertheless, the occurrence of IH is an important patient outcome, so alternative closure techniques for reducing IH should be studied in this patient population. Synopsis In a single-institutional study, the incidence of incisional hernia was 17% after cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy. Independent risk factors of incisional hernia were older age, female gender and obesity.

Evaluating Disparities in Colon Cancer Survival in American Indian/Alaskan Native Patients Using the National Cancer Database.

BACKGROUND: Studies demonstrate higher mortality rates from colon cancer in American Indian/Alaskan Native (AI/AN) patients compared to non-Hispanic White (nHW). We aim to identify factors that contribute to survival disparities. METHODS: We used the National Cancer Database to identify AI/AN (n = 2127) and nHW (n = 527,045) patients with stage I-IV colon cancer from 2004 to 2016. Overall survival among stage I-IV colon cancer patients was estimated by Kaplan-Meier analysis; Cox proportional hazard ratios were used to identify independent predictors of survival. RESULTS: AI/AN patients with stage I-III disease had significantly shorter median survival than nHW (73 vs 77 months, respectively; p < 0.001); there were no differences in survival for stage IV. Adjusted analyses demonstrated that AI/AN race was an independent predictor of higher overall mortality compared to nHW (HR 1.19, 95% CI 1.01-1.33, p = 0.002). Importantly, compared to nHW, AI/AN were younger, had more comorbidities, had greater rurality, had more left-sided colon cancers, had higher stage but lower grade tumors, were less frequently treated at an academic facility, were more likely to experience a delay in initiation of chemotherapy, and were less likely to receive adjuvant chemotherapy for stage III disease. We found no differences in sex, receipt of surgery, or adequacy of lymph node dissection. CONCLUSION: We found patient, tumor, and treatment factors that potentially contribute to worse survival rates observed in AI/AN colon cancer patients. Limitations include the heterogeneity of AI/AN patients and the use of overall survival as an endpoint. Additional studies are needed to implement strategies to eliminate disparities.

Improving Mental Health Support, Career Transitions and Access to Health Care for Surgical Residents.

OBJECTIVE: To increase access to mental health support, assist with career transitions, and improve access to health care. DESIGN: Retrospective survey data. SETTING: General surgery residency program. PARTICIPANTS: Surgical residents. RESULTS: We developed three programs to address the issues above. The "Fifth Tuesday of the Month" program allows residents to take time off during the first Tuesday morning of any month with five Tuesdays. The Physician Wellness Collaborative provides confidential, affordable, and easy-to-access counseling resources for residents. Residents are automatically signed up for a session to establish care. The Peer Resident Mentorship Program matches a fourth-year resident with a first-year resident based on personal and professional interests to help ease the transition and improve career satisfaction. All programs were associated with improvement in related outcome measures on our institution's annual program evaluation survey. CONCLUSIONS: At our institution, we introduced three simple and accessible programs aimed at increasing access to mental health support, assisting with career transitions, and improving work-life balance. These programs have improved related outcomes in our residents and can be easily implemented at any program.

Decreased Intestinal Microbiota Diversity Is Associated With Increased Gastrointestinal Symptoms in Patients With Chronic Pancreatitis.

OBJECTIVES: Chronic pancreatitis (CP) is characterized by abdominal pain, recurrent hospitalizations, frequent exposure to antibiotics, nutritional deficiencies, and chronic opioid use. Data describing the gut microbial community structure of patients with CP is limited. We aimed to compare gut microbiota of a group of patients with severe CP being considered for total pancreatectomy with islet autotransplantation (TPIAT) with those of healthy controls and to associate these differences with severity of clinical symptoms. METHODS: We collected stool from healthy donors (n = 14) and patients with CP (n = 20) undergoing workup for TPIAT, in addition to clinical metadata and a validated abdominal symptoms severity survey. RESULTS: Patients with CP had significantly lower alpha diversity than healthy controls ( P < 0.001). There was a significantly increased mean relative abundance of Faecalibacterium in healthy controls compared with patients with CP ( P = 0.02). Among participants with CP, those with lower alpha diversity reported worse functional abdominal symptoms ( P = 0.006). CONCLUSIONS: These findings indicate that changes in gut microbial community structure may contribute to gastrointestinal symptoms and provide basis for future studies on whether enrichment of healthy commensal bacteria such as Faecalibacterium could provide clinically meaningful improvements in outcomes for CP patients undergoing TPIAT.

Donor Microbiota Composition and Housing Affect Recapitulation of Obese Phenotypes in a Human Microbiota-Associated Murine Model.

Human microbiota-associated (HMA) mouse models offer a valuable approach to study the role of intestinal microbiota in the development of obesity. In this study, we used an HMA model to evaluate whether engraftment of human obese or lean microbiota, from each of three donors, could recapitulate host phenotypes under conventional and specific-pathogen-free housing. Microbiota engraftment was correlated with donor relative abundances of the class Bacteroidia (Spearman's ρ = 0.73, P ≤ 0.001), and one obese donor resulted in significant weight gain (P ≤ 0.003) and compromised insulin sensitivity under conventional housing. SPF housing partially blunted phenotypic response. Results of this study indicate that our HMA model partially recapitulates obese phenotypes under conventional housing and highlights a need to consider donor-specific effects as well as housing conditions when studying the role of the microbiota in obesity.

Effect of COVID-19 precautions on the gut microbiota and nosocomial infections.

COVID-19 precautions decrease social connectedness. It has been proposed that these measures alter the gut microbiota, with potential clinical consequences. We tested this hypothesis in patients with acute myeloid leukemia (AML) receiving inpatient chemotherapy, a population with extensive exposure to the nosocomial setting and at high risk for infections. Hospitalized patients with AML contributed stool samples to a biorepository protocol that was initiated before COVID-19 and continued without change through the pandemic. Patient-, disease-, and treatment-related characteristics remained the same in the two eras and the only change in clinical care was the implementation of COVID-19 precautions in March 2020. The incidence of all-cause nosocomial infections during the pandemic was lower than in the pre-COVID-19 era. Multivariable analysis revealed an imprint of COVID-19 precautions in the gut microbiota as a viable mechanistic explanation. In conclusion, COVID-19 precautions alter the gut microbiota, thereby mediating pathogen susceptibility and nosocomial infections.

Altered microbiota-host metabolic cross talk preceding neutropenic fever in patients with acute leukemia.

Despite antibiotic prophylaxis, most patients with acute leukemia receiving mucotoxic chemotherapy develop neutropenic fever (NF), many cases of which remain without a documented etiology. Antibiotics disrupt the gut microbiota, with adverse clinical consequences, such as Clostridioides difficile infection. A better understanding of NF pathogenesis could inform the development of novel therapeutics without deleterious effects on the microbiota. We hypothesized that metabolites absorbed from the gut to the bloodstream modulate pyrogenic and inflammatory pathways. Longitudinal profiling of the gut microbiota in 2 cohorts of patients with acute leukemia showed that Akkermansia expansion in the gut was associated with an increased risk for NF. As a prototype mucolytic genus, Akkermansia may influence the absorption of luminal metabolites; thus, its association with NF supported our metabolomics hypothesis. Longitudinal profiling of the serum metabolome identified a signature associated with gut Akkermansia and 1 with NF. Importantly, these 2 signatures overlapped in metabolites in the γ-glutamyl cycle, suggesting oxidative stress as a mediator involved in Akkermansia-related NF. In addition, the level of gut microbial-derived indole compounds increased after Akkermansia expansion and decreased before NF, suggesting their role in mediating the anti-inflammatory effects of Akkermansia, as seen predominantly in healthy individuals. These results suggest that Akkermansia regulates microbiota-host metabolic cross talk by modulating the mucosal interface. The clinical context, including factors influencing microbiota composition, determines the type of metabolites absorbed through the gut barrier and their net effect on the host. Our findings identify novel aspects of NF pathogenesis that could be targets for precision therapeutics. This trial was registered at www.clinicaltrials.gov as #NCT03316456.

Gut microbiota response to antibiotics is personalized and depends on baseline microbiota.

BACKGROUND: The magnitude of microbiota perturbations after exposure to antibiotics varies among individuals. It has been suggested that the composition of pre-treatment microbiota underpins personalized responses to antibiotics. However, this hypothesis has not been directly tested in humans. In this high-throughput amplicon study, we analyzed 16S ribosomal RNA gene sequences of 260 stool samples collected twice weekly from 39 patients with acute leukemia during their ~ 4 weeks of hospitalization for chemotherapy while they received multiple antibiotics. RESULTS: Despite heavy and sustained antibiotic pressure, microbial communities in samples from the same patient remained more similar to one another than to those from other patients. Principal component mixed effect regression using microbiota and granular antibiotic exposure data showed that microbiota departures from baseline depend on the composition of the pre-treatment microbiota. Penalized generalized estimating equations identified 6 taxa within pre-treatment microbiota that predicted the extent of antibiotic-induced perturbations. CONCLUSIONS: Our results indicate that specific species in pre-treatment microbiota determine personalized microbiota responses to antibiotics in humans. Thus, precision interventions targeting pre-treatment microbiota may prevent antibiotic-induced dysbiosis and its adverse clinical consequences. Video abstract.

Intestinal organoids: a model to study the role of microbiota in the colonic tumor microenvironment.

Colorectal cancer (CRC) is the third most common cause of cancer worldwide. Recent studies have suggested that a dysbiotic shift in the intestinal microbial composition of CRC patients influences tumorigenesis. Gut microbes are known to be integral for intestinal homeostasis; however, the mechanisms by which they impact CRC are unclear. Further knowledge about these complex interactions may guide future CRC management. Thus, it is crucial to establish high-quality experimental models to understand the relationship between host, tumor, microbiota and their metabolic interactions. In this review, we highlight the significance of intestinal microbiota and their metabolites in CRC, challenges with current experimental models, advantages and limitations of organoid culture and future directions of this novel model system in CRC-associated microbiome research.

Peri-operative antibiotics acutely and significantly impact intestinal microbiota following bariatric surgery.

Bariatric surgery is the most effective treatment for weight loss. Vertical sleeve gastrectomy (VSG) involves the resection of ~ 80% of the stomach and was conceived to purely restrict oral intake. However, evidence suggests more complex mechanisms, particularly postoperative changes in gut microbiota, in facilitating weight loss and resolving associated comorbidities. VSG in humans is a complex procedure and includes peri-operative antibiotics and caloric restriction in addition to the altered anatomy. The impact of each of these factors on the intestinal microbiota have not been evaluated. The aim of this study was to determine the relative contributions of each of these factors on intestinal microbiota composition following VSG prior to substantial weight loss. Thirty-two obese patients underwent one of three treatments: (1) VSG plus routine intravenous peri-operative antibiotics (n = 12), (2) VSG with intravenous vancomycin chosen for its low intestinal penetrance (n = 12), and (3) caloric restriction (n = 8). Fecal samples were evaluated for bacterial composition prior to and 7 days following each intervention. Only patients undergoing VSG with routine peri-operative antibiotics showed a significant shift in community composition. Our data support the single dose of routine peri-operative antibiotics as the most influential factor of intestinal microbial composition acutely following VSG.