About

Hisham Hussan, M.D. is an Associate Professor in the Department of Internal Medicine at UC Davis Health. His clinical focus is on gastroenterology, with particular interests in improving gastrointestinal symptoms, colorectal cancer prevention in adults with or without inherited predispositions, and enhancing gastrointestinal health in adults with obesity or prior bariatric surgery. Dr. Hussan is dedicated to helping patients achieve a better quality of life by applying the most recent evidence-based medicine combined with high levels of empathy in patient-centered, value-based care. His research primarily investigates the interface of energy balance and nutrition, the colonic microbiome and metabolome, and their impact on colorectal cancer risk. Additionally, he focuses on improving colorectal cancer screening using artificial intelligence. Dr. Hussan's academic background includes an M.D. from Damascus University School of Medicine, and he completed his internship, residency, and fellowship at St. Louis University School of Medicine. His contributions have been recognized through various awards, including the Dr. Michael Grever Clinical Research Award in Gastroenterology and the Colorectal Cancer Prevention Award from the American College of Gastroenterology.

Research topics

• Internal medicine
• Medicine
• Oncology
• General surgery
• Gastroenterology

Selected publications

• The Impact of Metabolic Bariatric Surgery on Inflammatory Bowel Disease Risk and Outcomes in Adults With Obesity: a Propensity-matched, Nationwide, Analysis

  Obesity Surgery · 2026-05-05

  articleOpen accessSenior author

  INTRODUCTION: The risk of de novo inflammatory bowel disease (IBD) after metabolic bariatric surgery (MBS) has been described, but the timing and severity of de novo IBD is unclear. METHODS: Using MarketScan Databases, patients with severe obesity undergoing Roux-en-Y-gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) were propensity-matched with patients with severe obesity without MBS (controls). Adjusted hazard ratio (aHR) assessed ulcerative colitis (UC) or Crohn's disease (CD) hazard <3 or ≥3 years from surgery or severe obesity. IBD severity was assessed using healthcare utilization-based proxies including medication exposure, IBD-related hospitalizations, and surgical interventions. RESULTS: The cohort included 100,832 adults with MBS versus 376,855 controls (76.0% females, median age of 44 years). The incidence of IBD was higher in MBS cohort versus controls (61.2 vs. 44.4 per 100,000 adults/year). Within 3 years, patients with MBS had a 24% lower risk of de novo IBD versus controls (aHR: 0.76, 95% CI: 0.60-0.95). When stratified by surgery and IBD type, VSG had reduction in CD risk (aHR=0.46, 95% CI:0.22-0.96), while RYGB had reduction in UC risk (aHR=0.22, 95% CI:0.06-0.75). After 3 years, patients with MBS, particularly VSG, had greater than 2-fold increased risk of IBD (aHR=2.28, 95%CI: 1.02-5.06). Markers of treatment intensity and healthcare utilization did not significantly differ between groups overall; however, a higher proportion of UC patients in the MBS cohort underwent colectomy, though absolute event numbers were small. (8.70% vs 1.57%, p=0.03). CONCLUSION: While MBS may lower IBD risk initially, IBD risk increases after 3 years, especially UC after VSG, and may be more severe as indicated by the higher proportion of colectomies for patients in the MBS cohort versus controls. Findings regarding treatment intensity should be interpreted cautiously, as objective measures of disease activity were not available in claims data.

  PublisherOA PDFDOI

• 1196 HIGH-DOSE BEAN INTAKE AS A GUT-TARGETED STRATEGY FOR HEALTHY AGING: TOLERABILITY AND FERMENTATION OUTCOMES IN A RANDOMIZED CROSSOVER TRIAL

  Gastrointestinal Endoscopy · 2026-05-01

  articleSenior author
  PublisherDOI

• 1196 HIGH-DOSE BEAN INTAKE AS A GUT-TARGETED STRATEGY FOR HEALTHY AGING: TOLERABILITY AND FERMENTATION OUTCOMES IN A RANDOMIZED CROSSOVER TRIAL

  Gastroenterology · 2026-05-01

  articleSenior author
  PublisherDOI

• Inactivation of Atp7b Copper Transporter in Intestinal Epithelial Cells Is Associated with Altered Lipid Processing and Cell Growth Machinery Independent from Hepatic Copper Accumulation and Severity of Liver Histology

  American Journal Of Pathology · 2025-10-16 · 1 citations

  articleOpen access

  mice. Intestine-specific Atp7b deficit affects systemic metabolic pathways and intestine morphology, and hepatic metabolic perturbations are associated with intestinal dysfunction, independently from hepatic copper accumulation, providing evidence that the WD phenotype is at least partially influenced by organ-specific ATP7B variants.

  PublisherDOI

• Development of a Brief Online Mindfulness-Based Intervention to Reduce Patient Anxiety Before a First-Time Screening Colonoscopy

  Journal of Cancer Education · 2025-03-31 · 3 citations

  articleOpen access

  To describe the development of an online mindfulness-based intervention (MBI) to reduce anxiety before a first-time screening colonoscopy among average-risk patients. A qualitative study used an iterative process guided by health behavior and mindfulness theories and feedback from a convenience sample of patients, endoscopy medical staff, and community members. Patient and medical staff (n = 18) were included in formative interviews (30-45 min), eight helped during intervention development sessions (15-90 min), and four community members reviewed the MBI in individual sessions (60 min). Interviews and sessions were recorded, transcribed verbatim, and analyzed using NVivo qualitative data software. Two themes emerged from the study: (1) both patients and medical staff reported that average-risk patients have pre-procedural anxiety before a first-time screening colonoscopy, and (2) using stakeholder-engaged strategies in an iterative process with both patients and medical staff is important so the developed intervention is acceptable to the priority population and to ensure medical accuracy and avoid disruption of workflow. Using an iterative process with key stakeholders is essential to develop interventions that are feasible and acceptable. The MBI developed through this process is being compared to usual care in a pilot randomized controlled trial to determine intervention feasibility and patient acceptability and to collect preliminary efficacy data. If efficacious, the developed MBI has the potential to reduce pre-procedural anxiety which may improve patient behaviors (e.g., bowel prep adherence and quality), patient satisfaction, and clinic workflow by reducing cancellation/no-shows, the amount of sedation required, and procedural time.

  PublisherOA PDFDOI

• Cooked Bean (Phaseolus vulgaris L.) Consumption Alters Bile Acid Metabolism in a Mouse Model of Diet-Induced Metabolic Dysfunction: Proof-of-Concept Investigation

  Nutrients · 2025-05-28 · 1 citations

  articleOpen access

  Background/Objectives: Metabolic dysregulation underlies a myriad of chronic diseases, including metabolic dysfunction-associated steatotic liver disease (MASLD) and obesity, and bile acids emerge as an important mediator in their etiology. Weight control by improving diet quality is the standard of care in prevention and control of these metabolic diseases. Inclusion of pulses, such as common bean, is an affordable yet neglected approach to improving diet quality and metabolic outcomes. Thus, this study evaluated the possibility that common bean alters bile acid metabolism in a health-beneficial manner. Methods: Using biospecimens from several similarly designed studies, cecal content, feces, liver tissue, and plasma samples from C57BL/6 mice fed an obesogenic diet lacking (control) or containing cooked common bean were subjected to total bile acid analysis and untargeted metabolomics. RNA-seq, qPCR, and Western blot assays of liver tissue complemented the bile acid analyses. Microbial composition and predicted function in the cecal contents were evaluated using 16S rRNA gene amplicon and shotgun metagenomic sequencing. Results: Bean-fed mice had increased cecal bile acid content and excreted more bile acids per gram of feces. Consistent with these effects, increased synthesis of bile acids in the liver was observed. Microbial composition and capacity to metabolize bile acids were markedly altered by bean, with greater prominence of secondary bile acid metabolites in bean-fed mice, i.e., microbial metabolites of chenodeoxycholate/lithocholate increased while metabolites of hyocholate were reduced. Conclusions: In rendering mice resistant to obesogenic diet-induced MASLD and obesity, cooked bean consumption sequesters bile acids, increasing their hepatic synthesis and enhancing their diversity through microbial metabolism. Bean-induced changes in bile acid metabolism have potential to improve dyslipidemia.

  PublisherOA PDFDOI

• Tu1139: SIROLIMUS FOR COLON POLYPOSIS IN PTEN HAMARTOMA TUMOR SYNDROME

  Gastroenterology · 2025-05-01

  articleSenior author
  PublisherDOI

• Sirolimus for Colon Polyposis in PTEN Hamartoma Tumor Syndrome

  Clinical and Translational Gastroenterology · 2025-06-06

  articleOpen accessSenior author

  INTRODUCTION: PTEN hamartoma tumor syndrome (PHTS) is a rare condition with a high rate of colon polyposis. Sirolimus may reduce colorectal polyps in PHTS. We designed a trial to assess the safety and impact of sirolimus on colon polyp burden in PHTS. METHODS: We performed an open-label trial of sirolimus for 1 year in adults with a PTEN pathogenic variant and colon polyposis. The primary outcome was change in polyp burden and staging. RESULTS: Five participants were enrolled, with 2 completing the planned study course. Baseline colonoscopies showed a mean polyp burden of 107 (range 31-184), with multiple histologic types. For the 2 patients completing the study, polyp burden decreased. DISCUSSION: Sirolimus has promise for reduction of colon polyp burden in PHTS, but side effects may limit usage. Future treatment trials in rare polyposis syndromes would benefit from the involvement of multiple centers to allow for improved recruitment.

  PublisherDOI

• S705 Sex-Specific Differences in Risk of Colorectal Polyps After Bariatric Surgery: Leveraging Machine Learning (ML) Techniques to Identify At-Risk Individuals

  The American Journal of Gastroenterology · 2025-10-01

  articleSenior author

  Introduction: Obesity doubles colorectal cancer (CRC) risk. Yet, severe weight loss has mixed effects on CRC risk. With the most potent weight loss method, bariatric surgery (BRS), CRC risk is reportedly reduced in women; however, this effect disappears after 10 years, whereas CRC risk is unchanged in men. Scarce data exists on the risk of pre-neoplastic colorectal polyps after BRS. We aim to investigate whether sex differences exist and the potential for predicting these risks using machine learning (ML) methods. Methods: This single-center, retrospective study included patients with a Body Mass Index (BMI) >35 kg/m² who underwent BRS from 2002-2023. Adults aged 18 and older who underwent a colonoscopy after Roux-en-Y gastric bypass or sleeve gastrectomy were compared to controls who had colonoscopies pre-surgery. Subjects with inflammatory bowel disease or personal/familial CRC were excluded. We evaluated the risk of polyps in men and women post-BRS, confirmed in a paired sensitivity analysis that examined the risk of polyps within these subjects. A prediction model employing 6 ML models was also created to identify individuals at risk for polyp development. Results: A colonoscopy was performed on 47% of BRS adults between 2002-2023. In total, 1,735 patients met the inclusion criteria (719 post-BRS and 1016 controls; 22% male). Pre-matching, both groups were similar in age and BMI at the time of surgery. BRS led to an impactful weight loss (mean post-BRS colonoscopy BMI of 35 kg/m² vs 44 kg/m² at baseline). Post-BRS adults trended towards a higher risk of polyps, which remained significantly elevated after propensity score matching (Hazard Ratio = 1.37, 95% CI: 1.10-1.72). Further, men had a higher risk of advanced polyps compared to women after BRS (Hazard Ratio = 2.09, 95% CI: 1.04-4.18). These findings persisted in a paired, propensity-matched analysis. Our ML analysis produced effective predictive models for identifying polyps, with Logistic Regression and Naïve Bayes showing the best discrimination capability—Logistic Regression at 65% sensitivity and Naïve Bayes at 71% specificity. Key predictive factors of polyps post-BRS included colonoscopy indication, age, metabolic markers, and sex. Conclusion: We identified an increased risk for polyps post-BRS and highlight sex-based trends in these risks. ML seems effective in predicting the risk of polyps, which provides an opportunity to enhance CRC screening uptake in at-risk adults post-BRS.

  PublisherDOI

• Colon Cancer, Version 3.2024, NCCN Clinical Practice Guidelines in Oncology

  Journal of the National Comprehensive Cancer Network · 2024-06-01 · 290 citations

  articleOpen access

  Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer and the second leading cause of cancer death in the United States. Management of disseminated metastatic CRC involves various active drugs, either in combination or as single agents. The choice of therapy is based on consideration of the goals of therapy, the type and timing of prior therapy, the mutational profile of the tumor, and the differing toxicity profiles of the constituent drugs. This manuscript summarizes the data supporting the systemic therapy options recommended for metastatic CRC in the NCCN Guidelines for Colon Cancer.

  PublisherOA PDFDOI

Frequent coauthors

• Somashekar G. Krishna

  89 shared

• Darwin L. Conwell

  University of Kentucky

  75 shared

• Peter P. Stanich

  The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute

  57 shared

• Alice Hinton

  The Ohio State University

  54 shared

• Steven K. Clinton

  The Ohio State University

  45 shared

• Kyle Porter

  33 shared

• Samer El-Dika

  Stanford Health Care

  30 shared

• Darrell M. Gray

  Institute for Advanced Journalism Studies

  27 shared

Education

• Fellowship, Gastroenterology

  Saint Louis University

  2014

• MD

  Damascus University

  2006

Awards & honors

• The Dr. Michael Grever Clinical Research Award in Gastroente…
• Colorectal Cancer Prevention Award for the best scientific p…
• Obesity Award for the best scientific papers, The American C…
• Best Senior Resident Lecture Award, Saint Louis University S…