Duodenal Neuroendocrine Tumors: A 20-Year Clinico-Pathological Appraisal at a Large Safety Net Hospital

Introduction: Duodenal Neuroendocrine tumors (dNETs) are rare neoplasms often incidentally identified on endoscopy. There is a significant knowledge gap of clinical and tumor related characteristics of dNETs and management remains controversial. The primary aim of this study was to identify clinicopathological characteristics and recognize potential racial differences among patients with dNETs at a large safety net hospital. Secondary objectives were to estimate overall survival (OS) and determine how frequently the updated World Health Organization 2019 guidelines for grading of NETs required diagnosis modification. Methods: Unique biopsy-proven dNET patients were identified at Boston Medical Center between 2002 and 2022. Clinicopathological characteristics were collected by chart review and compared between Black and non-Black patients. Pathologists updated the tumor grade in accordance with the WHO 2019 NET guidelines. OS was estimated using the Kaplan-Meier method. Results: Seventeen patients with dNETs which represented 6% of all gastrointestinal NETs were identified. Patients’ characteristics, including age, sex, BMI, and smoking history did not differ between Black and non-Black patients (Table 1). While a quarter of patients were asymptomatic, the majority reported symptoms at time of diagnosis, with abdominal pain (64.7%) being most common. Four of the dNETs were functional gastrinomas, 3 of which were associated with MEN-1. The majority (70.6%) of dNETs were local; however, 11.8% and 17.6% had evidence of regional or distant metastatic disease, respectively. Tumor characteristics did not differ among Black and non-Black patients, except dNETs localized more often to the first portion of the duodenum (D1) in non-Black patients (P=0.043, Table 1). Tumor grade required modification in 35.3% of dNETs. For the entire cohort, 10-year OS was 69% and OS of patients with age ≥ 65 was significantly shorter than in patients with age < 65 (10-year OS: 24% vs 100%, P=0.003 from Logrank test, Figure 1). Conclusion: This study characterized dNETs in the unique setting of a racially diverse large safety net hospital. In contrast to prior studies, clinical and tumor characteristics and OS did not differ across racial groups except in dNET localization and significantly shortened OS for patients > 65. The tumor grade required modification in a large proportion of cases, demonstrating the need for standardized pathological classification and clinical management.Figure 1.: Kaplan-Meier curves are shown for all patients and according to age (≥65 vs <65). Median overall survival (OS) for all patients was 18.5 years. Ten-year OS was 69% and OS of patients with age ≥ 65 was significantly shorter than in patients with age <65 (P=0.003 from log-rank test). Table 1. - Patient Clinical-Epidemiological and Tumor Characteristics Characteristic All dNETs (N=17) Black (N=11) Non-Black (N=6) P value Age at Diagnosis,yrs,(median,IQR) 62 (50-70) 60 (44-66) 67.5 (53.75-74.5) NS Sex, no. (%) NS male 9 (52.9) 7 (63.6) 2 (33.3) female 8 (47.1) 4 (36.4) 4 (66.7) Race, no. (%) NS White 5 (29.4) 0 (0.0) 5 (83.3) Black or African American 11 (64.7) 11 (100) 0 (0.0) Asian 1 (5.9) 0 (0.0) 1(16.7) BMI at Diagnosis,kg/m2(median,IQR) 30.2 (26.9-35.3) 32.5 (26.3-35.5) 30.2 (27.7-32.3) NS Smoking History, no. (%) NS Never 9 (52.9) 5 (45.5) 4(66.7) Active 1 (5.9) 1 (9.1) 0 (0.0) Former 7 (41.2) 5 (45.5) 2 (33.3) Size of Duodenal NET, no. (%) NS < 1 cm 6 (35.3) 2 (18.2) 4 (66.7) 1-2 cm 6 (35.3) 5 (45.5) 1 (16.7) >2 cm 2 (11.8) 1 (9.1) 1 (16.7) Unknown 3 (17.6) 3 (27.3) 0 (0.0) Number of Duodenal NETs, no. (%) NS Single 16 (94.1) 10 (90.9) 6 (100.0) Multiple 1 (5.9) 1 (5.9) 0 (0.0) Location of Duodenal NET, no. (%)* 0.043 D1 11 (64.7) 5 (45.5) 6 (100.0) non D1 6 (35.3) 6 (54.5) 0 (0.0) Stage no. (%) NS Local Disease 12 (70.6) 8 (72.7) 4 (66.7) Regional Metastatic Disease 2 (11.8) 1 (9.1) 1 (16.7) Distant Metastatic Disease 3 (17.6) 2 (18.2) 1 (16.7) NS is not significant. *The breakdown for non D1 tumors in Blacks was as follows: D2 alone (N=2; 18.2%), D1 plus D2 (N=2; 18.2%), D2 to D4 (N=1; 9.1%), and unknown (N=1; 9.1%). P values < 0.05 were considered significant for 2-sided t-test, Chi square, and Fisher exact test.