Introduction: Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) constitute a rare and heterogeneous group of tumors with varied biology.
Objectives: The aim of this study was to establish the clinical characteristics of patients with GEP-NEN and identify factors influencing their 5-year survival.
Patients and methods: The study included 122 patients living in Kraków or its administrative region, who were diagnosed with GEP-NEN between 2002 and 2011.
Results: The mean follow-up period was 4.9 ±2.8 years. The most frequent primary site of the tumor was the small intestine (n = 25; 20%), followed by pancreas (n = 23; 19%), rectum (n = 23; 19%), stomach (n = 21; 17%), appendix (n = 19; 16%), and colon (n = 11; 9%). There were 84 tumors classified as NEN G1; 31, as NEN G2; 5, as neuroendocrine carcinoma; and 1, as mixed adenoneuroendocrine carcinoma. Most well-differentiated GEP-NENs (n = 57; 57%) were diagnosed at stage I according to the American Joint Committee on Cancer / Union for International Cancer Control (AJCC/UICC) classification; 77% of NEN G1 (n = 64) were diagnosed at stage I, but the majority of NEN G2—at stage IV (n = 18; 58%). Metastases at diagnosis were found in 38 patients (34%). In 90% of the cases (n = 101), tumors were hormonally nonfunctional. The overall 5-year survival was 85%. In the univariate analysis, NEN G2 (P = 0.003), higher stage according to the AJCC/UICC classification (P <0.001), and metastases at diagnosis (P <0.001) were associated with poorer prognosis. In standardized multivariate models, higher stage (P = 0.02) and metastases at diagnosis (P = 0.02) were independent risk factors for death.
Conclusions: The most important factors affecting survival of patients with GEP-NENs are tumor stage and the presence of metastases at diagnosis. The analysis of single-center data improves identification of patients with poorer prognosis requiring a more aggressive approach.