Metachronous and synchronous cancers in patients with neuroendocrine tumors

Introduction: Neuroendocrine tumors (NETs) are a heterogeneous group of malignancies with various clinical presentations and growth rates. NET incidence has been estimated to 2.5-5 per 100,000 people per year, and NET prevalence is 35 per 100,000. They are frequently associated with synchronous or metachronous second primary malignancies (SPM). Methods: We retrospectively reviewed our institutional database on NET patients. We report on 30 patients with NETs and SPMs from a series of 262 patients with NETs: 10 patients with synchronous NETs (33.3%) and 20 with metachronous SPMs (66.6%). Results: The median patient age was 67 years. Of the 10 synchronous lesions, 50% were observed in the GI tract. The most common locations of these lesions were the colon (15%) and pancreas (25%). In 2 patients, there was an association of prostate neoplasia with a subsequent NET of the pancreas. Conclusions: Only few studies have examined the association between NETs and SPMs. Our study showed that the risk of second cancer following NETs is increased. In this single-institution retrospective review, our incidence of additional malignancies in patients with NET was 11.4%.