Survival following resection of pancreatic endocrine tumors: importance of R-status and the WHO and TNM classification systems

Objective. The aim of this study was to delineate the clinical outcomes and pathological characteristics of surgically resected endocrine tumors of the pancreas and to determine the importance of the World Health Organization (WHO) and tumor-node metastasis (TNM) classifications, resection status, and Ki-67 expression for long-term survival. Patients and methods. Sixty-nine patients underwent surgical tumor resection with curative intent during 1990-2007. Hospital records were reviewed retrospectively for medical, surgical, pathological, and radiological data. Results. Forty-one patients (59%) had non-functional tumors, 28 (41%) patients had functional tumors. Thirty-seven (54%) tumors were classified as WHO group 1 and the remaining 32 as WHO group 2. There were no poorly differentiated endocrine carcinomas. The overall R0-resection rate was 68%. Patients in whom all gross tumor was resected (R0/R1) had significantly better survival compared to patients with macroscopic residual disease (R2) (p < 0.001). There was no difference in survival between patients with R0 and R1 resections. Both the WHO (p < 0.001) and the TNM (p < 0.001) classifications significantly predicted five and 10-year survival after resection of the primary tumor. Survival analysis revealed significantly better outcome for patients with tumors with Ki-67 index < 2% (p = 0.003). Conclusions. Both WHO and TNM classifications reliably predict long-term survival in patients with resectable pancreatic endocrine tumors. R2 resection status predicted poor prognosis. R0 status did not improve prognosis relative to R1 status. Ki-67 index > 2% is a predictor of poor long-term survival.