The purpose of this study is to evaluate how well an investigational blood test performs. The study will look at the sensitivity and specificity of a blood-based multitranscriptome assay (NETest).

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.

Participants to be enrolled in the study will be recruited within the Gastrointestinal (GI) Clinic of Moffitt Cancer Center.