Symptom burden and outcomes among patients with early-onset and average-onset neuroendocrine neoplasms.

237 Background: The incidence of neuroendocrine neoplasms (NENs) is rising, particularly among younger individuals. However, data comparing clinical features and outcomes between early-onset NENs (EO-NENs) and average-onset NENs (AO-NENs) remain limited. Using a large national hospitalizations database, we aimed to compare patient characteristics, symptom burden, and clinical outcomes between these groups. Methods: We identified all hospitalizations involving patients with neuroendocrine neoplasms (NENs) in the National Inpatient Sample (NIS) from 2016 to 2020 using ICD-10 codes. Hospitalizations were stratified into an early-onset cohort (age < 50 years) and a late-onset cohort (age ≥50 years). Demographic characteristics, symptom burden, treatment interventions, and clinical outcomes were extracted and compared between cohorts. Independent sample t-tests were used for continuous variables, and chi-squared tests were used for categorical variables. A p-value of < 0.05 was considered statistically significant. Results: There were 22,555 hospitalizations with EO-NENs (median age 42.0) and 149,470 with AO-NENs (median age 67.0), respectively. The EO-NENs cohort had more females (55.3% vs. 49.3%, p < .001), a lower Charlson Comorbidity Index (CCI) (6.3 vs. 9.7, p < .002), and a greater likelihood of private insurance as primary payer (59.3% vs 28.3%, p < .001)). Hospitalizations for EO-NENs were more commonly associated with tumors of intestinal and thymic origin (p < .001). EO-NENs hospitalizations experienced a substantially higher symptom burden, including more nausea/vomiting (8.6% vs. 4.7%, p < .001), constipation (13.9% vs. 10.8%, p < .001), abdominal pain (1.9% vs 1.3%, p < .001) and anxiety (18.3% vs. 14.0%, p < .001). However, AO-NENs hospitalizations had higher rates of acute complications (heart failure, liver failure, sepsis) and in-hospital mortality (6.2% vs. 4.0%, p < .001). Early-onset hospitalizations underwent more chemotherapy (6.1% vs. 4.2%, p < .001) and surgical resection. Conclusions: We demonstrate significant clinical differences between EO- and AO-NENs, notably a higher symptom burden and relatively favorable outcomes. These data add to a growing body of literature indicating that EO-NENs characterize a clinically distinct subset. These findings underscore the need for age-adapted care pathways and further research into the unique biology that underpins the distinct clinical features of EO-NENs.