Clinical Utility Assay as a Biomarker for Gastroenteropancreatic and Lung Neuroendocrine Tumors

Inclusion Criteria: NET Cohort- * Patients with histologically or cytologically proven diagnosis of any grade, any stage NET of GEP or lung origin; In the first stage of the study (initial 50 patients) only patients with stage IV, well-differentiated tumors (G1/G2) will be enrolled. * Patients with stable or progressive disease, as documented on a scan (CT, MRI); Progression status will be documented on case report form (CRF). * Allowed prior therapies include: a.) Surgery (tumor surgery at least four weeks prior to study entry); b.) Locoregional therapy such as: chemoembolization, radio-embolization, radiofrequency ablation, radiotherapy at least six weeks prior to study entry; c.) Any number of previous lines of systemic therapy, providing that cytotoxic therapies (chemotherapy, PRRT) have been discontinued at least 4 weeks prior to study entry. Non-NET Cohort - * Healthy participants * Patients with histologically or cytologically proven diagnosis of any grade, any stage GI malignancies. Exclusion Criteria: NET Cohort - * Patients on treatment with cytotoxic agents (chemotherapy, PRRT). * Patients with renal insufficiency or congestive heart failure. * No other active malignancy within 3 years of enrolment except adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated stage I or II cancer from which the patient is currently in complete remission. Non-NET Cohort * Patients with GI malignancies with neuroendocrine differentiation.