Accuracy of grading pancreatic neuroendocrine tumors on endoscopic ultrasound-guided fine needle aspiration: a multi-institutional study

Abstract

Presenter: Ammar Javed MD | Johns Hopkins University School of Medicine Background: World Health Organization (WHO) grading system is prognostic in pancreatic neuroendocrine tumors (PanNETs). The concordance between WHO grade on cytological analysis (c-grade) of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) and histopathological analysis (h-grade) of surgical specimen is reported to be between 60 and 80%. Factors associated with concordance and trends of utilization of EUS-FNA for grading of PanNETs remain poorly understood. Methods: A multicenter retrospective study was performed on patients undergoing resection for PanNETs at four high-volume centers. Patients with functional or syndrome associated tumors, and those who received neoadjuvant therapy were excluded. Factors associated with concordance between c-grade and h-grade and trends of utilization of EUS-FNA for PanNETs over the last two decades were assessed. Results: Of the 1,398 patients included in the study, 704 (50.4%) underwent EUS-FNA; 579 (80.25) were diagnostic of PanNETs and WHO grade was reported for 296 (51.1%) patients. The concordance between c-grade and h-grade was 74.7% with moderate interrater agreement (Kc = 0.42, p<0.001). Significantly higher rates of concordance were observed in patients with smaller tumors ( < 2 vs. ≥2 cm, 70.1% vs. 29.9%, p = 0.030). The highest concordance was 100.0%and was observed in patients with small tumors without perineural invasion undergoing assessment between 2015-2019; perfect interrater agreement (Kc = 1.00, p<0.001). Over the last two decades an increase in the utilization of EUS-FNA from 31.5% to 61.4% was observed (p<0.001). Furthermore, EUS-FNA was more frequently diagnostic of PanNETs (p<0.001), and WHO grade was more frequently reported ( < 0.001). Despite increased utilization of EUS-FNA the rate of concordance did not change (p = 0.338). Conclusion: Higher rates of concordance between c-grade and h-grade are observed in patients with small PanNETs without perineural invasion. While an increase in the utilization and diagnostic accuracy of EUS-FNA has been observed, the concordance remains unchanged, suggesting a need for improved techniques and devices for accurate grading of PanNETs