Predicting resection margin status of pancreatic neuroendocrine tumors on CT: performance of NCCN resectability criteria

Objective To test the performance of the National Comprehensive Cancer Network (NCCN) CT resecta-bility criteria for predicting the surgical margin status of pancreatic neuroendocrine tumor (PNET) and to identify factors associated with margin-positive resection. Methods Eighty patients with pre-operative CT and upfront surgery were retrospectively enrolled. Two radi-ologists assessed the CT resectability (resectable [R], borderline resectable [BR], unresectable [UR]) of the PNET according to NCCN criteria. Logistic regression was used to identify factors associated with resection margin status. κ statistics were used to evaluate inter-reader agreements. Kaplan–Meier method with log-rank test was used to estimate and compare recurrence-free survival (RFS). Results Forty-five patients (56.2%) received R0 resection and 35 (43.8%) received R1 or R2 resection. R0 resection rates were 63.6–64.2%, 20.0–33.3%, and 0% for R, BR, and UR diseases, respectively (all p ≤ 0.002), with a good interreader agreement (κ, 0.74). Tumor size (<2 cm, 2–4 cm, and >4 cm; odds ratio (OR), 9.042–18.110; all p ≤ 0.007) and NCCN BR/UR diseases (OR, 5.918; p = 0.032) were predictors for R1 or R2 resection. The R0 resection rate was 91.7% for R disease <2 cm and decreased for larger R disease. R0 resection and smaller tumor size in R disease improved RFS. Conclusion NCCN resectability criteria can stratify patients with PNET into distinct groups of R0 resect-ability. Adding tumor size to R disease substantially improves the prediction of R0 resection, especially for PNETs <2 cm. Advances in knowledge: Tumor size and radiologic resectability independently predicted margin status of PNETs.