Neuroendocrine tumors

Neuroendocrine tumors

Overview

Neuroendocrine tumors are cancers that begin in specialized cells called neuroendocrine cells. Neuroendocrine cells have traits similar to those of nerve cells and hormone-producing cells.

Neuroendocrine tumors are rare and can occur anywhere in the body. Most neuroendocrine tumors occur in the lungs, appendix, small intestine, rectum and pancreas.

There are many types of neuroendocrine tumors. Some grow slowly and some grow very quickly. Some neuroendocrine tumors produce excess hormones (functional neuroendocrine tumors). Others don't release hormones or don't release enough to cause symptoms (nonfunctional neuroendocrine tumors).

Diagnosis and treatment of neuroendocrine tumors depend on the type of tumor, its location, whether it produces excess hormones, how aggressive it is and whether it has spread to other parts of the body.

Types of neuroendocrine tumors

Researchers classify NETs based on whether they release hormones:

Functional NETs release hormones and can cause hormone-related symptoms.

Non-functional NETs don’t release hormones. They can still cause symptoms if they impact an organ.

Researchers also classify neuroendocrine tumors based on where the tumor starts in your body. The most common types include:

Gastrointestinal neuroendocrine tumors (GI-NETs): NETs most commonly start in your gastrointestinal (GI) tract. Most start in your intestines, rectum or appendix. GI-NETs used to be called carcinoid tumors.

Lung neuroendocrine tumors: These tumors start in your lungs or bronchi, the tubes that carry air from your windpipe to your lungs. They’re the second most common type of NET and were also once called carcinoid tumors.

Pancreatic neuroendocrine tumors (P-NETs): These tumors start in your pancreas and are a type of pancreatic cancer. P-NETs are the third most common type of NET.

Less often, NETs may start in your:

Thyroid gland.

Parathyroid glands.

Pituitary gland.

Adrenal glands.

Thymus.

Symptoms

Neuroendocrine tumors don't always cause signs and symptoms at first. The symptoms you might experience depend on the location of your tumor and whether it produces excess hormones.

In general, neuroendocrine tumor signs and symptoms might include:

Pain from a growing tumor

A growing lump you can feel under the skin

Feeling unusually tired

Losing weight without trying

Neuroendocrine tumors that produce excess hormones (functional tumors) might cause:

Skin flushing

Diarrhea

Frequent urination

Increased thirst

Dizziness

Shakiness

Skin rash

Causes

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.

Risk factors

Researchers have linked NETs to rare inherited syndromes that involve mutations (changes) in certain genes. Your risk of developing a neuroendocrine tumor increases if you have one of these conditions: 

Multiple endocrine neoplasia (MEN): This condition causes overactive tumors to form in various organs and endocrine system glands. Type 1 (MEN1) is the most common cancer syndrome associated with NETs. It’s especially common in people with pancreatic NETs (P-NETs).

Von Hippel-Lindau syndrome: This condition increases your risk of benign and cancerous tumor growth in various parts of your body.

Neurofibromatosis type 1: This condition causes tumors to grow on your skin and nerves, affecting your eyes and other parts of your body.

Tuberous sclerosis complex: This condition causes benign tumors that can form anywhere on your body but most commonly in your brain.

Cowden syndrome: This condition causes benign tumor-like growths and increases your risk of some cancers.

Diagnosis

The tests and procedures you might undergo to diagnose a neuroendocrine tumor will depend on where your tumor is located in your body. In general, tests might include:

Physical exam. Your doctor may examine your body to better understand your signs and symptoms. He or she may feel for swollen lymph nodes or look for signs that a tumor is producing excess hormones.

Tests to look for excess hormones. Your doctor may recommend testing your blood or your urine for signs of excess hormones that are sometimes produced by neuroendocrine tumors.

Imaging tests. You might undergo imaging tests, such as ultrasound, CT and MRI, to create pictures of your tumor. For neuroendocrine tumors, pictures are sometimes created using positron emission tomography (PET) with a radioactive tracer that's injected into a vein.

Procedures to remove a sample of cells for testing (biopsy). To collect the cells, the doctor might insert a long, thin tube with a light and a camera on the end into your lungs (bronchoscopy), your esophagus (endoscopy) or your rectum (colonoscopy), depending on your situation. Sometimes, collecting a tissue sample requires surgery.

If there's a risk that your neuroendocrine tumor may have spread to other parts of your body, you might have additional tests to determine the extent of the cancer.

Treatment

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.

Type of Doctor Department : Oncologist, surgeon, endocrinologist, and gastroenterologist