Diagnosis
Neuroendocrine tumor diagnosis often starts with an exam. A healthcare professional might check your body for signs of cancer. Other tests and procedures might include blood and urine tests, imaging tests and a biopsy procedure.
Physical exam
A healthcare professional may examine your body to better understand your condition. The healthcare professional may feel for swollen lymph nodes or look for signs that a neuroendocrine tumor is producing excess hormones. The health professional may ask about your symptoms.
Tests to look for excess hormones
Neuroendocrine tumors sometimes make excess hormones. Your healthcare professional may recommend testing your blood or your urine for signs of extra hormones.
Imaging tests
Imaging tests make pictures of the inside of the body. For neuroendocrine tumors, imaging tests can make pictures that show the cancer's location and size. If there's a risk that the cancer may have spread, imaging tests can look for that too. Imaging tests might include:
Biopsy
A biopsy is a procedure to remove a sample of tissue for testing in a lab. In the lab, tests can show whether cancer cells are present. How a biopsy is done for a neuroendocrine tumor depends on where the cancer is in the body.
To collect the cells, a healthcare professional might use a long, thin tube with a light and a camera on the end. The tube can go down the throat to collect tissue from a lung tumor. This procedure is called bronchoscopy. The tube can go through the anus to get tissue from a tumor in the colon or rectum. This procedure is called colonoscopy. Sometimes, collecting a tissue sample requires surgery.
Examining the cancer cells
Healthcare professionals in the lab look at the neuroendocrine tumor cells with a microscope to decide if they are well differentiated or poorly differentiated. These terms describe how much the cancer cells look like healthy cells.
- Well-differentiated neuroendocrine tumors have cells that look similar to healthy cells. This usually means the cancer grows more slowly and is less aggressive. Well-differentiated cancers can still grow large and spread to other parts of the body, but they are less likely to do so. Healthcare professionals sometimes call these cancers carcinoid tumors.
- Poorly differentiated neuroendocrine tumors have cells that look different from healthy cells. This usually means the cancer grows quickly and is more aggressive. Healthcare professionals also call these cancers neuroendocrine carcinomas (NECs).
The differentiation tells the healthcare team about how the cancer is likely to act. It helps the healthcare team understand the prognosis and choose a treatment.
Measuring how fast the cancer cells are growing
Lab tests also can show how fast the cancer cells are growing and dividing. This is called the cancer's grade. The grade tells the healthcare team how the cancer is likely to behave.
To find the grade, healthcare professionals in the lab look at the cancer cells with a microscope. They count how many of the cells are dividing, called the mitotic rate. They also measure how many cells are actively growing, called the Ki-67 score.
Neuroendocrine tumor grades go from 1 to 3.
- Grade 1. These cancers are considered low grade. They tend to grow slowly.
- Grade 2. These cancers are considered intermediate grade. They usually grow and spread faster than grade 1 but slower than grade 3.
- Grade 3. These cancers are considered high grade. They tend to grow quickly.
The grade helps the healthcare team understand the prognosis and choose a treatment.
Treatment
Neuroendocrine tumor treatments include surgery, radiation therapy and medicines, such as chemotherapy, targeted therapy and immunotherapy. If the cancer is making excess hormones, medicines can help control the symptoms the hormones cause.
Your healthcare team considers many factors when creating your treatment plan. They might consider the type of tumor, its location and whether you're experiencing symptoms.
Surgery
Surgery is used to remove the neuroendocrine tumor. When possible, surgeons work to remove all of the cancer and some of the healthy tissue that surrounds it, called the margin. Removing the margin helps ensure that all the cancer cells are removed. If the cancer can't be removed completely, it might help to remove as much of it as possible.
Chemotherapy
Chemotherapy treats cancer with strong medicines. Many chemotherapy medicines exist. Most chemotherapy medicines are given through a vein. Some come in pill form.
For neuroendocrine tumors, chemotherapy might be the first treatment if surgery isn't possible. It can help treat cancer that spreads.
Chemotherapy is sometimes used before surgery to shrink the neuroendocrine tumor. This can make it easier to remove. Chemotherapy may be used after surgery to kill any cancer cells that may remain.
Targeted therapy
Targeted therapy for cancer is a treatment that uses medicines that attack specific chemicals in the cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die. Your cancer cells may be tested to see if targeted therapy is likely to be effective. One medicine that works in this way is everolimus (Afinitor).
For neuroendocrine tumors, targeted therapy might be used for cancers that can't be removed with surgery and cancers that spread.
Medicines to control excess hormones
If your neuroendocrine tumor releases excess hormones, your healthcare professional might recommend medicines to control the hormones. Medicines that work in this way are called somatostatin analog medicines. Examples include octreotide (Bynfezia Pen, Sandostatin) and lanreotide (Somatuline Depot). They can help with symptoms.
Immunotherapy
Immunotherapy for cancer is a treatment with medicine that helps the body's immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells. One medicine that works in this way is pembrolizumab (Keytruda).
For neuroendocrine tumors, immunotherapy might be an option for treating advanced cancers.
Radiation therapy
Radiation therapy treats cancer with powerful energy. Radiation treatments used for neuroendocrine tumors include:
- External beam radiation therapy. This treatment uses beams of energy that can come from X-rays, protons or other sources. During external beam radiation therapy, you lie on a table while a machine moves around you. The machine directs radiation to precise points on your body. Some types of neuroendocrine tumors may respond to this treatment. It might be recommended if surgery isn't an option.
- Peptide receptor radionuclide therapy. Peptide receptor radionuclide therapy uses a radiopharmaceutical to treat cancer. A radiopharmaceutical is a medicine that combines a medicine that targets cancer cells with a small amount of a radioactive substance. It allows radiation to be delivered directly to the cancer cells. One medicine that works in this way is lutetium Lu 177 dotatate (Lutathera). It is used to treat advanced neuroendocrine tumors.
More Information
Clinical trials
Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.
Coping and support
Coping with a neuroendocrine tumor diagnosis can be challenging. Some people say they felt shocked or worried when they found out they had a neuroendocrine tumor. A cancer diagnosis can bring up many emotions. With time, you'll find ways to cope with these feelings. Until then, here are some ideas for what to do next.
Learn enough about neuroendocrine tumors to make treatment decisions
Make a list of questions to ask at your next appointment. Bring a trusted person to help you take notes. Ask your healthcare team about reliable places to turn to for accurate information. The more you know about your cancer and your treatment options, the more confident you may feel as you make treatment decisions.
Connect with others with neuroendocrine tumors
Consider joining a support group, either in your community or online. A support group of people with the same diagnosis can be a source of useful information, practical tips and encouragement.
Ask your healthcare team about support groups in your area or contact the American Cancer Society. Find support online through Mayo Clinic Connect, which is a community where you can connect with others for support, practical information and answers to everyday questions.
Take time for yourself
Set aside time for yourself each day. Use this time to take your mind off your cancer and do what makes you happy. Even a short break for some relaxation in the middle of a day full of tests and scans may help you cope.
Find a good listener
Finding someone who is willing to listen to you talk about your hopes and fears can be helpful as you manage a cancer diagnosis. This could be a friend or family member. A counselor, medical social worker or clergy member also may offer helpful guidance and care.
Preparing for your appointment
Start by making an appointment with a doctor or other healthcare professional if you have any symptoms that worry you. If your healthcare professional thinks you might have a neuroendocrine tumor, that person will likely refer you to a specialist. The kind of specialist you see might depend on the part of the body that is affected. You might see a doctor who specializes in treating cancer, called an oncologist.
Because appointments can be brief, it's a good idea to be prepared. Here's some information to help you get ready and know what to expect from your doctor.
What you can do
- Be aware of any restrictions before your appointment. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as change your diet.
- Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down key personal information, including any major stresses or recent life changes.
- Make a list of all medicines, vitamins or supplements you're taking and the doses.
- Consider taking a family member or friend along. Sometimes it can be hard to remember all the information provided during an appointment. Someone who comes with you may remember something that you missed or forgot.
- Write down questions to ask your healthcare team.
Write down questions to ask your doctor
Your time with your healthcare team is limited, so prepare a list of questions to help you make the most of your time together. List your questions from most important to least important in case time runs out. For neuroendocrine tumors, some basic questions to ask include:
- What may be causing my symptoms or condition?
- What kinds of tests do I need?
- What do you recommend for next steps in determining my diagnosis and treatment?
- What are the alternatives to the approach that you're suggesting?
- Do I need to start treatment right away?
- What are the possible side effects of treatment?
- I have these other health conditions. How can I best treat them together?
- Are there any restrictions that I need to follow?
- Should I see a specialist?
- Where can I find more information?
In addition to the questions that you've prepared, don't hesitate to ask other questions during your appointment.
What to expect from your doctor
Your healthcare team is likely to ask you questions, such as:
- When did you first begin experiencing symptoms?
- How have your symptoms changed over time?
- How severe are your symptoms?
- What, if anything, seems to improve your symptoms?
- What, if anything, appears to worsen your symptoms?
Oct. 18, 2025