Mal, Madho

e16322 Background: Small intestine neuroendocrine carcinoma (NEC) is a rare, aggressive malignancy comprising less than 0.1% of gastrointestinal cancers. Population-level data remain limited, restricting understanding of long-term survival patterns, demographic disparities, and evolving disease burden. We evaluated survival outcomes, demographic predictors, and incidence trends of small intestine NEC in the United States. Methods: We conducted a retrospective population-based cohort study using SEER Research Data (17 registries, November 2024 submission). Patients diagnosed with malignant small intestine NEC (ICD-O-3 morphology code 9.3.3.1.2) between 2000 and 2022 were identified using SEER*Stat (v9.0.4.2). Variables including age group, sex, race, year of diagnosis, survival time, and vital status were analyzed in R (v4.5.1). Overall survival (OS) was estimated using Kaplan–Meier methods and compared using log-rank testing. Cox proportional hazards models identified independent predictors of OS. Annual case counts were modeled using time-series forecasting to project future incidence. Results: A total of 506 patients were included. Estimated OS was 94.4% (95% CI 92.4–96.4) at 1 year, 88.1% (85.3–91.0) at 3 years, and 82.4% (79.0–85.9) at 5 years, with a subset demonstrating survival beyond 15 years. Increasing age was associated with worse survival (log-rank p = 0.058). Significant racial differences in OS were observed (log-rank p < 0.0001). In multivariable analysis, race remained independently associated with OS. Incidence forecasting projected a modest increase in annual case burden over the next decade. Conclusions: Small intestine NEC demonstrates heterogeneous survival outcomes, significant demographic disparities, and projected growth in disease burden. These findings highlight the need for improved risk stratification, equitable access to care, and integration of molecular and treatment-level data to optimize management of this rare malignancy

e15598 Background: Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape of gastrointestinal (GI) malignancies. Emerging evidence suggests that gut microbiome composition plays a critical role in modulating the efficacy of immunotherapy. Antibiotics, by disrupting intestinal microbial diversity, may attenuate antitumor immune responses and compromise ICI outcomes. We evaluated time-dependent clinical outcomes associated with antibiotic exposure using real-world data. Methods: We conducted a retrospective cohort study using a large federated real-world database (2015-2025). Adults (18–89 years) with gastrointestinal or hepatobiliary malignancies (including colorectal, gastric, esophageal, and liver cancers) treated with ICI, receiving systemic antibiotics, were compared with matched controls without antibiotic exposure. Cohorts were balanced using 1:1 Propensity score matching for demographics, comorbidities, and treatment variables. The primary outcome was all-cause mortality at 30 days of ICI initiation; the secondary outcomes were hospitalization secondary to infectious and organ-related complications, overall survival at 1 and 3 years. Pre-specified subgroup analyses were performed in older adults ( > / = 65 years). Effect estimates were reported as risk ratios( RR), hazard ratios (HR), and absolute risk differences. Survival was analyzed using Kaplan–Meier curves and Cox proportional hazards models. Results: Within 30 days, antibiotic exposure was associated with significantly increased risks of Clostridioides difficile infection (RR 2.39), pneumonia (RR 2.93), acute kidney injury (RR 1.40), acute respiratory failure (RR 2.11), and neutropenia (RR 1.18) (all p < 0.05). Absolute risk differences translated to a number needed to harm (NNH) of approximately 38 for pneumonia, 143 for acute kidney injury, and ~140 for C. difficile infection. One-month mortality was modestly higher in the antibiotic group (5.4% vs 4.5%; HR 1.22; p = 0.014). However, no significant differences in mortality were observed at 6 months, 1 year, or 3 years, and survival curves converged over time. In the subgroup analysis of adults ≥65 years, early adverse event patterns were preserved, while long-term mortality remained unchanged. One-year hospital admission rates did not differ significantly between groups. Conclusions: Antibiotic exposure is associated with substantial early infectious and organ-related harm and a small increase in short-term mortality, without improvement in long-term survival, including among older adults. These findings highlight a critical opportunity for risk-adapted antibiotic stewardship and careful reassessment of empiric antibiotic use. Key words: ICI- Immune checkpoint inhibitors, RR- Risk ratio, HR- Hazard Ratio, NNH- Number Needed to Harm.

8075 Background: The role of definitive local thoracic therapy in metastatic non–small cell lung cancer (NSCLC) remains controversial. While stereotactic body radiation therapy (SBRT) is increasingly utilized, comparative survival outcomes with surgical resection in real-world populations remain limited. We evaluated survival and pulmonary outcomes associated with surgery versus SBRT in patients with stage IV NSCLC. Methods: We conducted a retrospective cohort study using the TriNetX Research Network including adults (≥18 years) with stage IV NSCLC treated between January 2013 and December 2023 who underwent definitive local thoracic therapy with either surgical resection or SBRT. Patients with small cell lung cancer, prior lung cancer diagnoses, prior thoracic radiation, or incomplete survival data were excluded. Propensity score matching (1:1) was performed to balance demographics, comorbidities, smoking history, and exposure to systemic therapy including chemotherapy and immunotherapy within 6 months of index treatment. Primary outcomes included landmark 1-year all-cause mortality and overall survival. Secondary outcomes included pneumonia and respiratory failure. Kaplan–Meier analysis and Cox proportional hazards regression were performed. Results: After matching, 1,934 patients were included (967 per cohort). At 1 year, surgical resection was associated with significantly lower mortality compared with SBRT (17.5% vs 31.4%; RR 0.56, 95% CI 0.47–0.66; p < 0.001), corresponding to an absolute risk reduction of 13.9% and an estimated number needed to treat of approximately 7. Kaplan–Meier analysis demonstrated superior survival in the surgical cohort (log-rank p < 0.001). Surgical resection remained associated with significantly improved long-term survival, with a 64% lower hazard of death (HR 0.36, 95% CI 0.30–0.44; p < 0.001) and prolonged median survival (3,942 vs 1,182 days). Pulmonary outcomes favored surgery. Pneumonia incidence was significantly lower in the surgical cohort at both 1 year (12.9% vs 29.3%; RR 0.44; p < 0.001) and 3 years (5.9% vs 14.2%; RR 0.42; p < 0.001). Rates of respiratory failure did not differ significantly between treatment groups. Conclusions: In this large real-world propensity-matched study, surgical resection was associated with significantly improved survival compared with SBRT in carefully selected patients with stage IV NSCLC. Surgery was additionally associated with lower long-term pulmonary infectious complications without increased respiratory failure risk. These findings suggest a potential role for aggressive local therapy in selected metastatic patients and support prospective trials to refine patient selection strategies.

3605 Background: Metabolic status and systemic inflammation are increasingly recognized as important modifiers of immune checkpoint inhibitor (ICI) response. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) exhibit anti-inflammatory and immunomodulatory properties and are widely used in diabetes and obesity. However, their clinical impact on immunotherapy outcomes in metastatic colorectal cancer (mCRC) remains unclear. Methods: We conducted a retrospective observational cohort study using the TriNetX Global Collaborative Network, including electronic health records from 170 healthcare organizations between 2015 and 2025. Adults with mCRC who received at least one ICI were identified. Patients prescribed GLP-1 RAs within six months before or after ICI initiation were compared with non-exposed controls. Patients with prior bariatric surgery were excluded. Cohorts were balanced using 1:1 propensity score matching for demographics, metabolic conditions, and major comorbidities. Primary endpoint was all-cause mortality at 1, 3, and 5 years. Secondary outcomes included pneumonia, heart failure exacerbation, and major abdominal surgical procedures. Survival analyses were performed using Kaplan–Meier methods and Cox proportional hazards models. Results: Among 8,304 eligible patients, 148 received GLP-1 RAs. After propensity matching, 138 patients were included in each cohort with well-balanced baseline characteristics. At 1 year, mortality was lower in the GLP-1 cohort (27.5% vs 40.6%), corresponding to a 32% relative risk reduction (RR 0.68, 95% CI 0.49–0.95) and reduced hazard of death (HR 0.67, 95% CI 0.43–1.03). This association persisted at 3 years (27.5% vs 41.3%; RR 0.67, 95% CI 0.48–0.93; HR 0.68, 95% CI 0.45–1.05) and 5 years (28.3% vs 42.0%; RR 0.67, 95% CI 0.49–0.93), with higher 5-year survival probability (50.5% vs 41.5%). Secondary outcomes favored GLP-1 exposure, including lower incidence of pneumonia (10.9% vs 17.4%; HR 0.58) and fewer heart failure exacerbations (23.9% vs 31.9%; HR 0.75). Rates of major abdominal surgical procedures were numerically lower in the GLP-1 cohort. Conclusions: In this large real-world cohort, concurrent GLP-1 RA exposure was associated with clinically meaningful and durable survival benefit in mCRC patients receiving ICIs, without increased adverse clinical outcomes. These findings suggest a potential immunometabolic interaction and support prospective evaluation of GLP-1–based strategies as adjunctive modifiers of immunotherapy response.

11186 Background: Cancer survival is shaped by tumor biology, treatment access, and socioeconomic context, yet population-level quantification of long-term survival disparities related to chemotherapy use and income is limited. We assessed five-year cancer-specific survival across demographic, treatment, and socioeconomic strata in a national registry. Methods: We performed a retrospective, population-based survival analysis using the Surveillance, Epidemiology, and End Results (SEER) database. Cancer-specific survival was evaluated at 12, 24, 36, 48, and 60 months after diagnosis. Outcomes were stratified by sex, race, chemotherapy receipt, and area-level median household income categories. Survival estimates were summarized descriptively and visualized using time-to-event curves. Results: Overall cancer-specific survival declined progressively over five years, from ~84% at 12 months to ~58% at 60 months. Sex differences were minimal, with similar five-year survival among males and females (~57–58%). Racial disparities were substantial: Asian/Pacific Islander patients demonstrated the highest survival across follow-up, while Black and American Indian/Alaska Native patients had lower early survival and persistent gaps at five years. Patients with recorded chemotherapy use had improved survival compared with those without or with unknown chemotherapy status; 12-month survival was ~88% versus ~80%, and five-year survival was ~65% versus ~57%, respectively. A pronounced socioeconomic gradient was observed: individuals in areas with median household income ≥$120,000 had higher five-year survival (~67%), whereas those in areas with income < $40,000 had markedly lower survival (~52%). Conclusions: In this national registry analysis, both chemotherapy utilization and higher socioeconomic status were strongly associated with improved long-term cancer survival, whereas persistent racial and income-related disparities remained evident. These findings highlight ongoing inequities in access to oncologic care and support the need for targeted policy interventions and equity-focused treatment delivery models. Interpretation should account for limitations inherent to observational registry data and potential residual confounding.