Neuroendocrine tumors often produce no symptoms in their early stages. NET symptoms, when they appear can include general cancer symptoms such as fatigue, a loss of appetite or weight loss. They also can produce symptoms according to where they are in the body, as well as the type of hormone they produce.

Depending on the tumor’s location, you may see one or more of the following NET symptoms: Pain that won't go away

Depending on the hormone the tumor releases, you may also experience NET symptoms such as:

Carcinoid syndrome happens when a neuroendocrine tumor produces too much serotonin. The extra hormones go to the bloodstream and cause symptoms such as:

Risk factors increase the chance of developing cancer and other conditions. You may have a higher risk of developing neuroendocrine tumor or cancer if you have certain inherited syndromes, including:

Neuroendocrine tumors get their name from their location, most commonly appearing in the GI tract, lungs, and pancreas. NETs in the intestine are sometimes called carcinoid tumors. NET types include:

Gastrointestinal NETs can form anywhere in the digestive system, from the esophagus to the anus. They most frequently appear in the small intestine and rectum. GI NETs include:

Lung NETs are types of lung cancer and include:

Pancreatic neuroendocrine tumor types include:

NETs that form elsewhere in the body include:

Doctors use a process called staging to determine if cancer has spread and, if so, how far. Staging helps doctors determine a prognosis (probable outcome based on others' experiences) and develop a treatment plan. Stage 0 describes the early signs of disease, and Stage 4 indicates an advanced case.

Your care team uses a T, N, M system to stage neuroendocrine cancer, considering these factors:

• Tumor: Your doctor looks at the tumor's size and location.
• Nodes: Your doctor determines if cancer has spread to nearby lymph nodes.
• Metastasis: Your doctor checks to see if cancer has spread (metastasized) to other body parts.

During the staging process, doctors also consider the grade of the tumor. Grading describes how fast tumor cells grow and divide.

Cancer staging can be complicated, and each type of neuroendocrine cancer has its own staging system. Your doctor will explain the staging process to you and help you understand the extent of the cancer you have.

Imaging tests provide detailed pictures of tissues and bones inside your body. Your doctor may order several imaging studies, such as:

• Computed tomography scan (CT scan): A specialized X-ray beam moves around your body while capturing pictures of bones, muscles, tissues, and organs.
• Magnetic resonance imaging scan (MRI): A large magnet, radio waves, and computer work together to take clear, detailed pictures.
• Positron emission tomography (PET) scan: This type of imaging measures your body's cell activity. You receive a small amount of a tracer (radioactive substance) that travels through your body. The tracer collects in areas of increased cell activity (typically indicating cancer) and appears brighter on the scan.
• PET/CT scan: PET and CT technology combine to show areas of increased cell activity and highly detailed images of nearby organs and tissues.
• PET/MRI scan: This PET and MRI combination shows cell differences and detailed images of the brain, internal organs and soft tissues. It uses less radiation than a CT scan.
• Ultrasound: This test uses sound waves to create images of the body's blood vessels, tissues, and organs.
• X-ray: This test uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.

Your doctor may take small samples of your urine or blood to check for levels of proteins, hormones, or other substances in your body. Lab tests can also help identify if you have genetic conditions that increase your risk of certain NETs.

With an endoscopy, your doctor inserts an endoscope (a thin, lighted tube) through the nose, mouth, or rectum to examine the digestive tract. They may also take tissue samples for a biopsy.

If imaging and lab tests indicate you might have neuroendocrine cancer, your doctor may request a biopsy. Your doctor removes a small tissue sample, and a pathologist analyzes the cells under a microscope.