Proliferative rate in endoscopic ultrasound fine‐needle aspiration of pancreatic endocrine tumors

BACKGROUND: The objectives of this study were to evaluate the role of endoscopic ultrasonography (EUS)-guided fine-needle aspiration (FNA) in the preoperative diagnosis of pancreatic endocrine tumors (PETs) and to investigate whether the Ki-67 index determined on cytologic material could help predict their behavior. METHODS: The study included 10 men and 5 women (ratio of men to women, 2:1) with a mean age of 62.4 years (range, 40-79 years). Diff-Quik- and Papanicolaou-stained FNA samples were analyzed retrospectively, and immunocytochemical stains were performed for chromogranin A, synaptophysin, vimentin, alpha-1-antitrypsin, and Ki-67 on cell block sections. The Ki-67 index was evaluated by using digital image-analysis software and was correlated with follow-up (mean, 21.5 months; range, 2-43 months). RESULTS: The overall survival was rate 86.7% (13 of 15 patients). Seven of 15 patients (46.7%) patients developed lymph node and/or hematogenous metastases. The Ki-67 index in PETs with no metastases was lower (mean, 6.3%; range, 2%-13%) than in clinically aggressive (metastatic) tumors (mean, 7.7%; range, 3%-27%; P = .03). None of the tumors that had a Ki-67 index < or =2% were metastatic. Both patients who died of disease had a Ki-67 index of 4%. CONCLUSIONS: Although tumors with metastatic potential tended to exhibit a slightly higher Ki-67 index, there was a significant overlap with nonmetastatic tumors, and PETs that had a very low proliferative rate still could behave aggressively; therefore, the authors concluded that the Ki-67 index does not predict the risk of disease progression in patients with PETs.