About

Samir Gupta is a Professor of Medicine at UC San Diego School of Medicine. His educational background includes a BA with distinction from the University of Michigan, an MD with distinction from the University of Michigan, and a MSc with distinction from the University of Texas Southwestern Medical Center. He completed his internship and residency at the University of Pennsylvania and fellowships at UC San Francisco. His research focuses on gastroenterology, particularly colorectal cancer screening, colonoscopy surveillance, and related clinical trials. He is involved in multiple NIH-funded projects, including studies on colorectal cancer screening hubs, post-polypectomy surveillance, and implementation science in colorectal cancer screening. His work also encompasses clinical trials and research on infectious diseases, respiratory conditions, and HIV treatment, with numerous publications derived from MEDLINE/PubMed sources.

Research topics

• Medicine
• Internal medicine
• Genetics
• Biology
• Psychology
• Demography
• Oncology
• Clinical psychology
• Computer Science
• Psychiatry
• Economics
• Bioinformatics
• Medical emergency
• Environmental health
• Pediatrics
• Endocrinology
• Microeconomics
• Cardiology
• Gastroenterology
• Gerontology
• Surgery
• Emergency medicine

Selected publications

• Black–White disparities across the colorectal cancer care continuum in the USA

  Nature Reviews Gastroenterology & Hepatology · 2025-07-21 · 2 citations

  reviewSenior author
  PublisherDOI

• Performance of Fecal Immunochemical Test in Individuals With Personal History of Polyps and Family History of Colorectal Cancer: A Systematic Review

  Clinical Gastroenterology and Hepatology · 2025-09-17

  review
  PublisherDOI

• Inhaler user awareness of climate implications: a Canadian survey

  2025-09-27

  articleSenior author

  <bold>Background:</bold> People with lung diseases are vulnerable to climate change; yet the most common inhaler device, metered dose inhalers (MDIs), have significant climate impacts. <bold>Aim:</bold> To understand inhaler users’ perspectives on climate change and awareness of inhaler climate implications. <bold>Methods:</bold> Canadians (aged ≥ 16) who reported using an inhaler in the previous 6 months were invited via health organizations' newsletters to complete a cross-sectional e-survey. Multivariate regression models assessed the association between sociodemographic factors and climate change risk perception index scores, inhaler disposal methods, awareness of inhaler climate impacts, and willingness of MDI users to switch to low carbon footprint devices. <bold>Results:</bold> There were 255 respondents (mean age 68 ± 12 years, 64% female, 80% MDI users). Most individuals were concerned about climate change (84%) but only 20% were aware that MDIs have high carbon footprints. Older individuals and women were less likely to be aware of the carbon footprint of MDIs, while higher education was associated with greater awareness (p<0.05). People who already experienced health changes due to climate events (31%) had higher climate change risk perception scores (p < 0.001). Most respondents reported disposing of their inhalers in garbage bins (58%) and when provincial pharmacy return programs were available (n=216) they were underutilized (26%). Nearly all MDI users (92%) were willing to switch to a lower carbon footprint device. <bold>Conclusions:</bold> Inhaler users are concerned about climate change but lack awareness of inhaler climate impacts. Interventions that promote education, use of low carbon devices, and sustainable disposal could reduce inhaler-related climate impacts.

  PublisherDOI

• Clinical Validation of a Circulating Tumor DNA–Based Blood Test to Screen for Colorectal Cancer

  JAMA · 2025-06-02 · 39 citations

  articleOpen access

  Importance: Colorectal cancer screening is widely recommended but underused. Blood-based screening offers the potential for higher adherence compared with endoscopy or stool-based testing but must first be clinically validated in a screening population. Objective: To evaluate the clinical performance of an investigational blood-based circulating tumor DNA test for colorectal cancer detection in an average-risk population using colonoscopy with histopathology as the reference method. Design, Setting, and Participants: Prospective, multicenter, cross-sectional observational study enrolling participants between May 2020 and April 2022 who were asymptomatic adults aged 45 to 85 years, at average risk of colorectal cancer, and willing to undergo a standard-of-care screening colonoscopy. Participants, staff, and pathologists were blinded to blood test results, and laboratory testing was performed blinded to colonoscopy findings. The study was conducted at 201 centers across 49 US states and the United Arab Emirates. Site-based and mobile phlebotomy were used for blood collection. Exposures: Participants were required to complete a screening colonoscopy after blood collection. Main Outcomes and Measures: The primary end points were sensitivity for colorectal cancer, specificity for advanced colorectal neoplasia (colorectal cancer or advanced precancerous lesions), negative predictive value for advanced colorectal neoplasia, and positive predictive value for advanced colorectal neoplasia. The secondary end point was sensitivity for advanced precancerous lesions. Results: The median age of participants in the evaluable cohort (n = 27 010) was 57.0 years, and 55.8% were women. Sensitivity for colorectal cancer was 79.2% (57/72; 95% CI, 68.4%-86.9%) and specificity for advanced colorectal neoplasia was 91.5% (22 306/24 371; 95% CI, 91.2%-91.9%). The negative predictive value for advanced colorectal neoplasia was 90.8% (22 306/24 567; 95% CI, 90.7%-90.9%) and the positive predictive value for advanced colorectal neoplasia was 15.5% (378/2443; 95% CI, 14.2%-16.8%). All primary end points met prespecified acceptance criteria. The sensitivity for advanced precancerous lesions was 12.5% (321/2567; 95% CI, 11.3%-13.8%), which did not meet the prespecified acceptance criterion. Conclusions and Relevance: In an average-risk colorectal cancer screening population, a blood-based test demonstrated acceptable accuracy for colorectal cancer detection, but detection of advanced precancerous lesions remains a challenge, and ongoing efforts are needed to improve test sensitivity. Trial Registration: ClinicalTrials.gov Identifier: NCT04369053.

  PublisherOA PDFDOI

• Colorectal Cancer Screening Modalities in the United States: Regional and Rural Variance, the Resilience of Colonoscopy, and the Rise of mt-sDNA Testing

  Cancer Prevention Research · 2025-08-28 · 2 citations

  article

  This study examined trends in colorectal cancer screening modality utilization across the United States from 2016 to 2022, leveraging a large national claims database. The purpose was to identify national, regional, and demographic patterns in screening behavior during a period that encompassed the introduction of multitarget stool DNA testing (mt-sDNA) and the COVID-19 pandemic. Among 6.9 million colorectal cancer screenings analyzed, overall utilization increased through 2019, dipped in 2020 due to pandemic disruptions, and rebounded by 2022. Colonoscopy remained the dominant modality, with its utilization increasing in both relative and absolute terms. mt-sDNA testing experienced rapid adoption, increasing from less than 1% to 17% of all screenings, whereas fecal occult blood testing and fecal immunochemical testing declined. Multinomial logistic regression revealed that utilization patterns varied significantly by region, rurality, sex, age, and year. The Midwest and rural patients exhibited higher uptake of both colonoscopy and mt-sDNA compared with other groups, whereas the West maintained the highest reliance on fecal occult blood testing and fecal immunochemical testing. Findings highlight the nonuniform adoption of screening modalities across regions, urban and rural patients, categories of sex, and age cohorts. Understanding these patterns can inform and improve future resource allocation with the goal of increasing colorectal cancer screening uptake and adherence. PREVENTION RELEVANCE: This study informs cancer prevention by revealing regional and demographic variation in colorectal cancer screening modality use. Understanding these evolving patterns can inform and improve targeted strategies and allocation of resources to improve screening uptake and adherence.

  PublisherDOI

• Characteristics of Postpolypectomy Colorectal Cancer Events and Deaths

  The American Journal of Gastroenterology · 2025-03-27 · 1 citations

  articleSenior authorCorresponding

  INTRODUCTION: Postpolypectomy colorectal cancers (PPCRCs) are diagnosed after a cancer-negative colonoscopy with polypectomy. Analyzing PPCRC characteristics informs prevention and early detection strategies. We investigated interval types and etiologies of PPCRCs using World Endoscopy Organization guidelines. METHODS: PPCRCs were identified in a retrospective cohort of US Veterans who underwent colonoscopy with polypectomy from 1999 to 2016. We classified PPCRCs into interval, noninterval type A, and noninterval type B, defined as cancers diagnosed before, at, and after next recommended surveillance examination, respectively. A root cause analysis was conducted to determine the most plausible etiology. RESULTS: We identified 396 PPCRC events and 90 PPCRC deaths over a median follow-up of 3.9 and 4.2 years, respectively. Among PPCRC events, 55% (95% confidence interval [CI] 50%-60%) were interval, 12% (95% CI 9%-15%) noninterval type A, and 33% (95% CI 29%-38%) noninterval type B. Interval cancers were more likely to be diagnosed at stage 4 than noninterval cancers (16% interval vs 2.1% noninterval type A, 8.3% noninterval type B, P = 0.003). Most interval cancers were due to possible missed lesions with adequate examinations (60%, 95% CI 53%-66%), whereas most noninterval cancers were likely new CRCs (type A: 48%, 95% CI 34%-62%; type B: 84%, 95% CI 77%-90%). Similar results were found for PPCRC deaths. DISCUSSION: Most PPCRC events and deaths were diagnosed before the next recommended examination, largely because of procedural factors, underscoring the need to optimize quality of baseline colonoscopy and polypectomy. Many PPCRCs were diagnosed after recommended examination, suggesting the need to improve patient adherence to recommended surveillance intervals.

  PublisherDOI

• 481: LARGE LANGUAGE MODELS ACCURATELY IDENTIFY DIAGNOSES FROM FREE TEXT WITHIN ELECTRONIC HEALTH RECORD DATA

  Gastroenterology · 2025-05-01

  article
  PublisherDOI

• Defying the Odds: A Rare Case of Giant Recurrent Retroperitoneal Liposarcoma Managed Over Eight Years

  Medical Journal of Dr D Y Patil Vidyapeeth · 2025-07-01

  articleOpen access1st author

  A BSTRACT Retroperitoneal liposarcoma (RPLS) is a rare and challenging soft tissue sarcoma, comprising 15–20% of adult retroperitoneal tumors. Despite surgical resection, recurrence rates are high, and adjuvant therapies are limited. We present a unique case of a 42-year-old woman with recurrent RPLS, who experienced five recurrences and underwent four major surgeries over eight years. The most recent surgery involved removing a massive 13 kg, 40 × 25 × 17 cm tumor compressing adjacent organs. Histopathology consistently confirmed well-differentiated liposarcoma (WDLS), with one recurrence showing myxoid features. This case emphasizes the importance of aggressive surgical resection in managing recurrent RPLS, as well as vigilant long-term follow-up for early detection of recurrences. Despite significant morbidity from repeated surgeries, the patient showed remarkable recovery and long-term survival, highlighting the potential for favorable outcomes with individualized, multidisciplinary care. Our case, featuring long survival and multiple relapses, is unique, as only six cases with survival beyond six years have been reported in the past 12 years.

  PublisherDOI

• S1004 Predictors of Low Esophageal Biopsy Rates During Endoscopy for Food Impaction and Resultant Delayed Diagnosis and Missed Cases of Eosinophilic Esophagitis in a National Veteran Population

  The American Journal of Gastroenterology · 2025-10-01

  article

  Introduction: Best practice guidelines recommend obtaining esophageal biopsies during an index food impaction to evaluate for eosinophilic esophagitis (EoE). We performed a retrospective study using a national sample to evaluate rates of esophageal biopsy during an index foreign body/food impaction and assess outcomes related to EoE diagnoses. Methods: We utilized national Veterans Affairs (VA) data to identify adults ≥18 years of age diagnosed with a first esophageal foreign body (FB) (International Classification of Diseases [ICD]-9 and -10 codes) or food impaction (FI) (ICD-10 codes) between January 1, 2008 (first ICD codes for EoE) and December 31, 2023. Diagnoses of esophageal cancer were excluded. Descriptive statistics characterizing biopsy rates and time to EoE diagnosis were performed. Multivariable regression analyses were used to evaluate factors associated with obtaining biopsies. Results: Four thousand five hundred forty-seven unique patients in the Veterans Health Administration (median age 68, 96% men, 81% White) underwent an esophagogastroduodenoscopy (EGD) for an index esophageal FB/FI. Esophageal biopsies were collected in 28.5% (2,153/7,547) of these patients. Ten point three percent (778/7,547) of patients had biopsies documented from multiple esophageal levels. Biopsy frequency was significantly higher following the EoE guidelines in 2018 (31.1%) compared to previous years (26.7%) (P < 0.0001). Ten percent (755/7,547) of the cohort had a diagnosis of EoE: 38% diagnosed at the time of index FB/FI, and 62% after presentation. Median delay in EoE diagnosis was 103 days from index FB/FI (Q1-Q3: 39-473 days). 43.1% (3,256/7,547) of the total cohort never had documented esophageal biopsies collected during their lifetime in the VA system. In multivariable analyses, younger age, performing an “overnight” vs “daytime” endoscopy, male vs female sex, and lower VA facility complexity were associated with obtaining biopsies. Race, ethnicity, and use of propofol during the procedure did not significantly impact biopsy rates. Conclusion: In a national sample, less than 1 in 3 patients presenting with an index FB/FI and who underwent an EGD had esophageal biopsies obtained during the procedure. Older patients and women were at higher risk for not having biopsies collected. More than half of EoE cases were diagnosed after this index presentation, with a median delay in diagnosis of 103 days. Almost 1 in 2 FB/FI patients never had esophageal biopsies collected, suggesting hundreds of EoE cases may have been missed. Adherence to the best practice recommendation of obtaining esophageal biopsies during index FI may improve EoE diagnosis timing and initiation of treatment.

  PublisherDOI

• Mo1223: LOW ESOPHAGEAL BIOPSY RATES DURING INDEX FOOD IMPACTION RESULT IN DELAYED DIAGNOSIS AND POTENTIAL MISSED CASES OF EOSINOPHILIC ESOPHAGITIS: ANALYSIS FROM A NATIONAL SAMPLE OF VETERANS

  Gastroenterology · 2025-05-01

  article
  PublisherDOI

Recent grants

• NIH Grant I01HX00157405

  NIH · 2019

• NIH Grant UG3CA233314

  NIH · $604k · 2020

• Cancer Control Program

  NIH · $40.3M · 1996–2031

• NIH Grant U54CA163308

  NIH · $10.0M · 2017

• Post-polypectomy Surveillance for Reducing Colon Cancer Incidence and Mortality

  NIH · $2.8M · 2018–2024

Frequent coauthors

• Tonya Kaltenbach

  152 shared

• Marı́a Elena Martı́nez

  145 shared

• Ranier Bustamante

  VA San Diego Healthcare System

  130 shared

• Ashley Earles

  125 shared

• Celette Sugg Skinner

  120 shared

• Andrew J. Gawron

  VA Salt Lake City Healthcare System

  115 shared

• Sapna Syngal

  Cancer Genetics (United States)

  99 shared

• Amit G. Singal

  96 shared