NET guidelines for white patients may not fit Asian patients.

Abstract

Introduction: Pancreatic neuroendocrine tumors (pNETs) are slow growing, malignant tumors that show different survival outcomes by race. Current size-based guidelines were largely developed in White patients. Our aim was to investigate tumor size and incidence of lymph node metastasis (LNM) between White and Asian pNET patients to evaluate generalizability of established guidelines.

Methods: Using the National Cancer Database (NCDB), we conducted a multi-institutional analysis of patients with low grade, resected, nonfunctional, sporadic, non-metastatic pNETs. Chi-squared tests were implemented to determine correlation between PTS and LMN incidence as well as race and LMN incidence. A logistic regression model was utilized to determine correlation between LMN, tumor size, and race. Overall survival was assessed using the Kaplan-Meier method.

Results: A total of 4977 pNET patients (205 Asian and 4772 White) were included in our analysis. Asian patients presented with smaller tumors (3.0 ​cm vs 3.9 ​cm, p ​= ​0.029) but when grouped by size, there was no difference in the distribution (p ​= ​0.77). White patients demonstrated a higher incidence of lymph node metastasis at presentation compared to Asian patients (27 ​% vs 19 ​%, p ​= ​0.013), a higher likelihood of an R0 resection (95.3 ​% vs. 89.3 ​%, p ​< ​0.0001). Within both populations, tumor size (<2 ​cm, 2-3 ​cm, and ≥3 ​cm) positively correlated with incidence of LNM (11.5 ​%, 24.6 ​%, and 39.1 ​%). No difference of LNM was seen between racial cohorts at PTS <3 ​cm, however, Asian patients were less likely to exhibit LNM at PTS ≥3 ​cm (28.2 ​% and 39.5 ​%, p ​= ​0.04). Overall survival was not significantly different between racial groups (p ​= ​0.92).

Conclusion: Size based surgical resection guidelines for pancreatic neuroendocrine tumors based on a predominantly White patient population may not be generalizable to the Asian population. Within this population, we found the risk of lymph node metastasis did not increase at similar rates with increasing primary tumor size.