Circulating biomarkers for nonfunctional gastroenteropancreatic neuroendocrine neoplasm:Where do we stand?

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) encompass a heterogeneous group of tumors associated with variable presentations, growth rates, and prognoses. The majority of GEP-NENs are nonfunctional, and their diagnosis remains challenging given the often subtle and variable clinical manifes-tations of these tumors. As a consequence, GEP-NENs are often recognized at an advanced stage; indeed, most patients with nonfunctional GEP-NENs exhibit metastatic disease at diagnosis. Lack of treatment op-tions as well as limitations in currently available imaging modalities and biomarkers make it challenging to manage NENs. Thus, novel biomarkers are needed to provide high sensitivity and specificity for minimum disease detection and to predict treatment efficacy and prognosis. Although tissue-based biomarker data can provide such information, circulating biomarkers such as NETests, circulating tumor cells, and microR-NAs, are superior owing to their easy accessibility and the ability for repeated real-time sampling.Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) encompass a heterogeneous group of tumors associated with variable presentations, growth rates, and prognoses. The majority of GEP-NENs are nonfunctional, and their diagnosis remains challenging given the often subtle and variable clinical manifes-tations of these tumors. As a consequence, GEP-NENs are often recognized at an advanced stage; indeed, most patients with nonfunctional GEP-NENs exhibit metastatic disease at diagnosis. Lack of treatment op-tions as well as limitations in currently available imaging modalities and biomarkers make it challenging to manage NENs. Thus, novel biomarkers are needed to provide high sensitivity and specificity for minimum disease detection and to predict treatment efficacy and prognosis. Although tissue-based biomarker data can provide such information, circulating biomarkers such as NETests, circulating tumor cells, and microR-NAs, are superior owing to their easy accessibility and the ability for repeated real-time sampling.115-19