NETs are new growths that can be found in any of the organs mentioned above, but most commonly in the digestive tract. Occasionally these tumors are also found as liver metastases without a clear primary organ of origin.
NETs are rare, since they are found in less than 2 percent of malignancies found in the digestive tract. The most common type of these is the carcinoid tumor, which grow slowly compared to the two other types, the pancreatic endocrine tumor and the gastropancreatic NET.
Signs and symptoms of NET may vary depending on the organ involved. However, most of these tumors are not symptomatic till late in the course of the disease, and signs and symptoms may be vague and non-specific, such as weight loss, loss of appetite, diarrhea, unusual bleeding or discharge, abdominal discomfort, night sweats, etc.
Diagnosis is likewise difficult because of the late manifestations. Detection usually follows when the cancer cells have spread to other organs (metastasis) and symptoms have occurred. Laboratory studies used to arrive at a diagnosis are usually multiple, including blood tests, x-ray, CT scan, MRI and biopsy.
Staging of the disease depends on tumor size, extent of spread and involvement of lymph nodes.