Long-term outcomes and prognostic factors in 78 Japanese patients with advanced pancreatic neuroendocrine neoplasms: a single-center retrospective study

Abstract

Despite an increase in the number of Japanese patients with pancreatic neuroendocrine neoplasms, long-term outcomes and prognostic factors, especially for those with advanced disease, remain unclear. We retrospectively reviewed the medical records of 78 patients with unresectable pancreatic neuroendocrine neoplasms treated at our hospital from January 1987 to March 2015. Survival analyses were performed using Kaplan–Meier methods. Prognostic significance of several clinicopathological factors were analyzed by univariate and multivariate analyses using a Cox regression model. Median overall survivals of pancreatic neuroendocrine tumor (n = 64) and pancreatic neuroendocrine carcinoma (n = 14) were 83.7 and 9.1 months, respectively (hazard ratio: 0.02, 95% confidence interval: 0.01–0.08, P < 0.001). Although no significant differences were observed using a Ki-67 cut-off value of 2% (hazard ratio: 0.46, 95% confidence interval: 0.16–1.13, P = 0.0989), a Ki-67 cut-off of 10% was a significant predictor in patients with pancreatic neuroendocrine tumor (hazard ratio: 9.95, 95% confidence interval, 3.01–32.97, P < 0.001). Treatment after the advent of targeted therapy (hazard ratio: 0.07, 95% confidence interval: 0.03–0.19, P < 0.001) and the presence of bone metastases (hazard ratio: 4.38, 95% confidence interval: 1.42–11.29, P = 0.013) were significant prognostic factors in patients with pancreatic neuroendocrine tumor evaluated by univariate analysis. Multivariate analysis also revealed that a Ki-67 index ≥10% (hazard ratio: 38.8, 95% confidence interval: 8.42–226.62, P < 0.001), approval of targeted therapy (hazard ratio: 0.02, 95% confidence interval: 0.00–0.11, P < 0.001) and bone metastases (hazard ratio: 5.56, 95% confidence interval: 1.10–24.00, P = 0.039) were independent prognostic factors. We elucidated the long-term outcomes and prognostic factors in Japanese patients with advanced pancreatic neuroendocrine neoplasms.