Abstract The proliferation of advanced endoscopic resection techniques has provided a minimally invasive alternative to esophagectomy and revolutionized outcomes for patients with early-stage esophageal adenocarcinoma (EAC). This paradigm shift and the resulting research data on clinical and histologic determinants of treatment outcome have highlighted the heterogeneity of outcomes within EAC staged as T1 by invasion depth. Multidisciplinary cancer care teams are now routinely facing difficult decisions regarding the management of high-risk T1 EAC to balance the risk of long-term lymph node (LNM) or distant metastasis against the risks of surgical resection. In this review, we summarize the current state of knowledge regarding the staging and risk stratification of T1 EAC, with particular attention to features that contribute to a higher risk of LNM and cancer mortality. We review recent clinical trial data on positioning the use of endoscopic resection (cap-assisted or submucosal dissection) versus surgical resection in high-risk T1 EAC patients and describe adjunctive techniques to further improve risk stratification and treatment. Finally, we explore emerging and future directions, such as artificial intelligence and advanced biomarker analysis to further aid decision-making and enhance patient outcomes.
Early Experience With Beta-Lactam Therapeutic Drug Monitoring in an Outpatient Parenteral Antimicrobial Therapy (OPAT) Program
Abstract We describe early experience with beta-lactam therapeutic drug monitoring (TDM) in a high-volume outpatient parenteral antimicrobial therapy program. In selected patients, TDM informed dose optimization and toxicity mitigation. Illustrative cases highlight feasibility and emerging lessons supporting beta-lactam TDM in outpatient care.
Lynch Syndrome in the General Population: Clinical Phenotype of
PMS2
Pathogenic Variants
PURPOSE The Lynch syndrome (LS) genes, MLH1 , MSH2 , MSH6 , and PMS2 , are considered to be some of the highest-priority genes to be tested for population genomic screening, with the aim to prevent and detect cancers early in those with a higher risk for such diagnoses. The objective of this study was to determine the risk of cancer associated with pathogenic variants in MLH1 , MSH2 , MSH6 , or PMS2 in the general population to build evidence-based guidelines for population genomic screening METHODS This retrospective case-control study uses Helix Research Network data from 230,159 participants across nine US health systems. Variant interpretation was performed following the American College of Medical Genetics and Association for Molecular Pathology guidelines. Clinical diagnoses were identified from electronic health records and claims data for 11 cancer types associated with LS, including colorectal and endometrial cancers. RESULTS Individuals with pathogenic variants in MLH1 , MSH2 , and MSH6 showed substantial risk for LS-related cancers compared with those without pathogenic variants. Conversely, individuals with pathogenic variants in PMS2 had no increase in risk for all 11 LS-associated cancers with hazard ratio (HR) of 1.0 (95% CI, 0.6 to 1.8) compared with those without a pathogenic variant. There was a small increase in risk when restricting the analysis to colorectal cancer with an HR of 3.5 (1.7-7.4). This increase in colorectal cancer risk was predominantly observed after age 60 years, 10 years after US Preventive Services Task Force guidelines recommend starting colonoscopies for the average population. Up to age 60 years, 2.6% of individuals with PMS2 pathogenic variants were diagnosed with colorectal cancer, closer to the general population (0.7%) than those with MLH1 (37.3%), MSH2 (28.9%), or MSH6 (6.7%) pathogenic variants. For 100,000 individuals screened for PMS2 , 854 additional colonoscopies would be performed, which would prevent or detect early 3.2 colorectal cancers. CONCLUSION This analysis across nine health systems highlights the clinical phenotypes of PMS2 pathogenic germline variants in the entire population.
The Epidemiology of Young-Onset Barrett’s Esophagus in the United States
Introduction: Young-onset esophageal adenocarcinoma (EAC) often presents at advanced stages and is associated with poor outcomes. We aimed to examine the epidemiology of young-onset Barrett’s esophagus (BE) using the TriNetX database. Methods: Young-onset BE patients (age 18 to younger than 50 y) with esophagogastroduodenoscopy (EGD) within 1 year before index BE diagnosis between 2014 and 2023 were included. Negative binomial regression was used to evaluate incident-time trends, and logistic regression to assess for independent predictors of young-onset BE. Results: BE diagnosis was present in 76,691 (3.3%) of 2,337,786 patients that underwent EGD, of which 14,120 (18%) had prevalent young-onset BE. BE dysplasia/EAC was present in 6% of young-onset patients at initial diagnosis. Conventional BE risk factors also predicted young-onset BE: GERD (OR=2.4), White race (OR=2.4), male sex (OR=2.2), smoking (OR=1.2), and obesity (OR=1.1). Each additional risk factor increased the probability of BE prevalence by 74% in young patients versus 54% in older patients. The prevalence of young-onset BE was 4.5% with GERD and ≥3 additional risk factors, and 2.3% when ≥3 risk factors were present. Discussion: Young-onset BE accounts for 18% of all BE cases, demonstrates a striking 6% rate of dysplasia/neoplasia at initial diagnosis, and has a prevalence of 4.5% in those with GERD and ≥3 risk factors. These findings suggest that young-onset BE is an important patient population that merits further study. Additional studies are necessary to study the cost-effectiveness of BE screening in younger patients with multiple risk factors.
Risk Factors for Developing Candidemia after Gastrointestinal Perforation and/or Ischemia and Its Outcomes: A Matched Case–Control Study
Background: Candidemia is a serious complication after gastrointestinal (GI) perforation and/or ischemia, yet most evidence pools candidemia with intra-abdominal candidiasis (IAC). We sought candidemia-specific risk factors after GI perforation and/or ischemia and evaluated associated outcomes. Methods: We conducted a single-center, retrospective matched case–control study of adults undergoing emergency surgical procedure for GI perforation and/or ischemia and admitted to a surgical intensive care unit. Cases with candidemia during index admission were matched 4:1 to controls by age, Charlson Comorbidity Index, and surgical procedure year. Conditional logistic regression assessed pre-specified risk factors, and exploratory outcomes included mortality, length of stay, and days on invasive ventilation. Results: Twenty-four cases were matched to 99 controls. Factors identified to be independently associated with candidemia include the presence of IAC (adjusted OR [aOR]: 5.51, 95% CI: 1.61, 18.89; p = 0.007), upper GI injury (aOR: 4.28, 95% CI: 1.52–12.08; p = 0.006), and diffuse intra-abdominal contamination, compared with contained/none (aOR: 3.21, 95% CI: 1.06–9.74; p = 0.040). Among candidemia cases, species distribution was Candida albicans 41.7%, C. glabrata 33.3%, C. parapsilosis 12.5%, with single cases of C. tropicalis, C. krusei , and C. dubliniensis . Candidemia was associated with a longer hospital length of stay (+13.97 d; 95% CI: 0.90–27.04; p = 0.036), without significant differences in ICU stay, duration of invasive ventilation, or mortality. Conclusions: After GI perforation and/or ischemia, the risk of candidemia is highest in patients with upper GI injury and diffuse contamination, independent of IAC. These readily identifiable operative features may guide targeted surveillance and selective early antifungal strategies. Prospective validation is warranted.
Abstract 7577: Advancing the science, practice and impact of COE.
Abstract Introduction: COE has become the gold standard in addressing health disparities. COE’s value is emphasized by NIH and leading cancer-related organizations e.g., AACR. The Alliance for COE (The Alliance) mission is to advance the art, science, and impact of COE; promote community health and wellness; and reduce cancer burden and disparities. Methods: This abstract builds on the Alliance’s Science of Community Outreach and Engagement (SoCOE) Conference a NCI R13 funded series. SoCOE Conference is organized by 10 NCI-designated Cancer Centers to provide a platform for COE academic-clinical-policy-community stakeholders to share best practices for solution-focused community responsive cancer prevention, diagnostics, therapeutics and survivorship research and practice. Results: > 500 researchers, clinicians, policymakers, healthcare administrators, with >12% being survivors and/or advocates, participated in our SoCOE Conferences. The delegates’ recommendations are: Decentralize who/entities that hold all the power in science and clinical research (trials). Communities hold valuable, necessary wisdom and resources to inform and guide science Include multisectoral partners early and always Community capacity building and compensation with gratitude Mentoring of junior COE researchers, clinicians, policymakers, healthcare administrators, survivors and advocates with humility is a must Develop virtual communities to share best practices across cancer centers and within regions Develop working groups to identify and explore commonalities across COE work in rural/urban, diverse/homogenous spaces Publish Science of COE papers on various topics related to COE Frameworks and evidenced-solutions Provide community reports on best practice guide that can be widely available to be shared locally and in-person, and digitally Partner and learn from COE teams working with other cultural/ethnic groups Attend to, measure and remedy societal/social drivers of health disparities that mirror barriers to care, and research engagement and participation. Discussion: Informed by our community advisory boards and the findings for our SoCOE Conferences, we present the pillars of the Alliance to tackle population cancer burden and disparities: Training future COE leaders/advocates, Advocating for public health policies/guidelines, Increasing access to cancer prevention and care that will also increase access to studies, Engaging and partnering with multisectoral stakeholders and communities, Building community capacity, Advancing COE science through catchment-relevant research, and Leading bi-directional communication and information and resource sharing between catchment area communities and cancer centers. The expectation and impact of COE can only be achieved if COE teams are valued, supported cancer center members with community advisory boards and community as cancer centers’ priority population. Citation Format: Kimlin Ashing, CHARNITA ZEIGLER-JOHNSON, Hayley S. Thompson, Kim Rhoads, Nadine Barrett, Lisa Carter Bawa, Timiya S. Nolan, Monica Baskin, Vanessa B. Sheppard, Marvella E. Ford, Erica Phillips, Lorna H. McNeill, Folakemi T. Odedina. Advancing the science, practice and impact of COE [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7577.
Outcomes and Surgical Management of Malignant Rhabdoid Tumor of the Kidney: A Report From the Pediatric Surgical Oncology Research Collaborative
ABSTRACT Purpose Malignant rhabdoid tumor of the kidney (MRTK) is a rare, aggressive tumor seen in young children. The optimal timing of resection for locally advanced tumors is not well‐defined. The purpose of this study is to evaluate modern oncologic outcomes and the impact of surgical timing. Methods A multicenter retrospective review was performed by institutions participating in the Pediatric Surgical Oncology Research Collaborative. Children younger than 21 years old with MRTK diagnosed between 2000 and 2022 were included. Results Sixty‐nine patients were identified with MRTK and met the inclusion criteria. Median age of diagnosis was 10.1 months. Overall survival (OS) at 1, 5, and 10 years was 49%, 32%, and 19%, respectively. Patients with local Stage III disease who underwent upfront resection ( n = 18) compared to those who had delayed resection after NAT ( n = 15) had a similar OS, median OS greater than 60 months versus 14.6 months, respectively; p = 0.396. The surgical timing groups were balanced in terms of the presence of metastasis, length of follow‐up, and tumor characteristics. There was one occurrence of primary intraoperative tumor spill and two occurrences of organ injury in the upfront resection group compared to none in the delayed resection group. Conclusion MRTK carries a poor prognosis despite multimodal treatment. Histologic diagnosis may not be confirmed at presentation, and MRTK cannot be reliably distinguished from Wilms tumor on imaging alone. As overall survival is similar, the decision regarding surgical timing in locally advanced tumors should be individualized based on perceived resectability, balancing the risk of intraoperative complications against the possibility of tumor progression during neoadjuvant therapy.
1430: SYSTEMIC THROMBOLYSIS VS CATHETER-DIRECTED INTERVENTION FOR PULMONARY EMBOLISM: A MULTI-CENTER STUDY
INTRODUCTION: The adjunctive use of p53 immunohistochemistry has been proposed as a potential tool to improve risk stratification in Barrett's esophagus (BE) with conflicting results. We performed a systematic review and meta-analysis to evaluate the performance of p53 in predicting progression to advanced neoplasia (high-grade dysplasia [HGD] and esophageal adenocarcinoma [EAC]) among patients with BE. METHODS: We searched multiple databases for studies that evaluated the use of aberrant p53 in esophageal biopsies among patients with BE and reported progression rates to HGD/EAC. The outcomes were p53 test characteristics and incidence and risk ratio (RR) for progression to HGD/EAC in patients with and without aberrant p53 using random effects models. RESULTS: Among the 27 included studies, the proportion of patients with aberrant p53 expression at baseline was 20% (95% CI: 14%, 27%). The rate of progression with and without aberrant p53 was 8 per 100 person-years (95% CI: 6, 11) and 0.3 per 100 person-years (95% CI: 0.1, 0.6), respectively. Compared with patients without aberrant p53 expression, those with aberrant p53 had a higher risk for progression to HGD/EAC in cohort studies (RR = 10.2 [95% CI: 6.9, 15.0]) and case control studies (RR = 3.3 [95% CI: 2.5, 4.4]). The sensitivity for progression for non-dysplastic Barrett's esophagus and low-grade dysplasia/indefinite for dysplasia was 42% and 77% and specificity was 96% and 76%, respectively. DISCUSSION: While aberrant p53 expression has been associated with an increased risk of progression to advanced neoplasia in patients with BE undergoing surveillance, the diagnostic characteristics are suboptimal precluding uniform clinical adoption. Prospective studies with standardized grading protocols are needed to determine whether p53-guided surveillance strategies can meaningfully improve patient outcomes.