can the WHO classification system be simplified?
PURPOSE: The WHO classification for well-differentiated pancreatic endocrine neoplasms (PENs) incorporates both stage and grade. This study compares the prognostic value of a simplified staging and grading system with the WHO system in a large single-institution study. PATIENTS AND METHODS: A prospective database (1982 to 2005) identified 183 patients who underwent operative treatment for PENs. Tumors were staged (< 2 cm primary, >/= 2 cm primary, or metastases) and graded (low grade: no necrosis and < two mitoses/50 high-powered fields [HPF]; or intermediate grade: necrosis and/or >/= two mitoses/50 HPF) with a simplified schema. Influence of stage and grade on recurrence and disease-specific survival (DSS) was determined. Prognostic strength was assessed with the concordance index (CI). RESULTS: Median age of the 183 patients was 56 years, and 53% were women. Median follow-up time was 44 months (range, 1 to 226 months). Classification identified 28 patients (15%) with WHO 1.1 disease
