Neuroendocrine tumors (NETs) are a type of rare and heterogeneous tumors that arise from the neuroendocrine cells, which are cells that release hormones into the bloodstream in response to nerve impulses. These tumors can occur anywhere in the body, but most commonly occur in the gastrointestinal tract, pancreas, and lungs.

NETs can be categorized based on their location, size, and hormone production. They can be either functional or non-functional, depending on whether they produce hormones or not. Functional NETs produce hormones, which can cause specific symptoms and are used for diagnosis and treatment monitoring. Non-functional NETs do not produce hormones and are usually diagnosed when they have grown large enough to cause symptoms or are detected incidentally.

Symptoms of NETs vary depending on the location and hormone production of the tumor. Common symptoms include abdominal pain, diarrhea, flushing, wheezing, weight loss, and fatigue. Diagnosis of NETs involves a combination of imaging tests, such as CT or MRI scans, and blood tests to measure hormone levels.

Treatment options for NETs depend on the location, size, and stage of the tumor, as well as the presence or absence of symptoms. Treatment options include surgery, chemotherapy, radiation therapy, targeted therapy, and somatostatin analogs. The choice of treatment is individualized and based on the specific characteristics of the tumor and the patient's overall health.

The exact cause of neuroendocrine tumors isn't known. These cancers begin in neuroendocrine cells that have traits similar to those of nerve cells and hormone-producing cells. Neuroendocrine cells are found throughout your body.

Neuroendocrine tumors begin when neuroendocrine cells develop changes (mutations) in their DNA. The DNA inside a cell contains the instructions that tell the cell what to do. The changes tell the neuroendocrine cells to multiply rapidly and form a tumor.

Some neuroendocrine tumors grow very slowly. Others are aggressive cancers that invade and destroy normal body tissue or spread (metastasize) to other parts of the body.

The treatment options for your neuroendocrine tumor will depend on the type of tumor, its location, and whether you're experiencing signs and symptoms of excess hormones produced by the tumor.

In general, neuroendocrine tumor treatment options might include:

• Surgery. Surgery is used to remove the tumor. When possible, surgeons work to remove the entire tumor and some of the healthy tissue that surrounds it. If the tumor can't be removed completely, it might help to remove as much of it as possible.
• Chemotherapy. Chemotherapy uses strong drugs to kill tumor cells. It can be given through a vein in your arm or taken as a pill. Chemotherapy might be recommended if there's a risk that your neuroendocrine tumor might recur after surgery. It might also be used for advanced tumors that can't be removed with surgery.
• Targeted drug therapy. Targeted drug treatments focus on specific abnormalities present within tumor cells. By blocking these abnormalities, targeted drug treatments can cause tumor cells to die. Targeted drug therapy is usually combined with chemotherapy for advanced neuroendocrine tumors.
• Peptide receptor radionuclide therapy (PRRT). PRRT combines a drug that targets cancer cells with a small amount of a radioactive substance. It allows radiation to be delivered directly to the cancer cells. One PRRT drug, lutetium Lu 177 dotatate (Lutathera), is used to treat advanced neuroendocrine tumors.
• Medications to control excess hormones. If your neuroendocrine tumor releases excess hormones, your doctor might recommend medications to control your signs and symptoms.
• Radiation therapy. Radiation therapy uses powerful energy beams, such as X-rays and protons, to kill tumor cells. Some types of neuroendocrine tumors may respond to radiation therapy. It might be recommended if surgery isn't an option.

Other treatments might be available to you depending on your particular situation and your specific type of neuroendocrine tumor.