Neuroendocrine Cancer

Neuroendocrine cancer is an uncommon cancer that starts in neuroendocrine cells. Neuroendocrine cells are found throughout your body. They help your body respond to stress, control hormones, digest food, and keep many organs working. These cells have 2 roles:

1. They act like nerve cells
2. They make hormones (chemical messengers that travel through the body to tell organs what to do)

Neuroendocrine cancer can cause very different symptoms from person to person or none at all. Some people are diagnosed quickly. Others are not diagnosed for years because symptoms can be mild or look like other health problems. Neuroendocrine cancer may be found incidentally during other tests or procedures for other reasons.

Neuroendocrine cancer can grow in many parts of the body. This includes the digestive system, lungs, pancreas, and other organs. Some grow slowly over many years. Others grow more quickly.

The most common locations are:

• Digestive system (stomach, small intestine, colon, rectum, appendix)
• Lungs
• Endocrine organs (thyroid and adrenal glands – these make hormones that help control how the body works)

Types of Neuroendocrine Cancer

Understanding a few key terms about neuroendocrine cancer can help you and your care team talk more clearly about your specific diagnosis. These cancer cells are described based on whether they make hormones, how they look under a microscope, and how fast they grow. Together, these features help explain what symptoms may happen and what treatment options are available.

Functioning - Whether cancer cells produce hormones

• Functional – produce hormones; symptoms related to increased hormone activity
• Non-functional –don’t produce hormones; either no symptoms, or symptoms are related to the cancer cell location and effect on nearby organs

Differentiation - How abnormal the cancer cells look under a microscope 

• Well-differentiated –cancer cells look well-organized
• Poorly differentiated –cancer cells look disorganized and messy, with dead cells mixed in

Grade - How quickly the cancer cells are growing and dividing 

• Low grade – cancer cells grow slowly
• High grade – cancer cells grow quickly

NETs vs. NECs

• Slower growing (low-grade), well-differentiated NENs are called neuroendocrine tumors (NETs)
• Faster growing (high-grade), poorly differentiated NENs are called neuroendocrine carcinomas (NECs)

Symptoms at diagnosis and treatment options will depend on four factors:

1. Location of the cancer
2. Whether the cancer cell is functional or non-functional
3. Whether the cancer cell is growing slowly or quickly (the grade)
4. Differentiation type of the cancer

Risk Factors

For most cases, there is no known cause of neuroendocrine cancer. A small number of diagnoses happen because of rare, inherited conditions. If you have a family history of endocrine tumors or are diagnosed at a young age, ask your care team about genetic testing. Most people with neuroendocrine cancer do not have an inherited condition. Environmental risks that can cause neuroendocrine cancer are currently unknown, but researchers are exploring this.

Signs & Symptoms

Symptoms are caused by the location of the NEN and if it secretes any hormones. As mentioned previously, NENs are either functional or non-functional.

For functional NENs, symptoms are more likely related to increased hormone activity. Some examples are fast heartbeat, flushing of the skin and face, blood pressure

changes, and abdominal pain. Some NENs can produce higher levels of hormones, which can lead to hormone-related syndromes:

• Carcinoid syndrome (often from small intestine or lung NENs making serotonin): flushing, diarrhea, wheezing, belly cramping, feeling anxious
• Insulinoma syndrome: low blood sugar (shakiness, sweating, confusion)
• VIPoma syndrome: watery diarrhea
• Zollinger‑Ellison syndrome: frequent or hard‑to‑treat stomach ulcers, belly pain

With non-functional NENs, symptoms may be linked to the nearby organs, or there may be no symptoms at all. Based on the location of the NEN, symptoms may include:

• Insulinoma syndrome (low blood sugar)
• VIPoma syndrome (diarrhea)
• Zollinger-Ellison syndrome (stomach ulcers)

With non-functional NENs, symptoms may be linked to the nearby organs, or there may be no symptoms at all. Based on the location of the NEN, symptoms may include:

• Nausea and vomiting
• Unexplained weight loss or feeling full quickly
• Belly pain or cramps
• Rashes
• Rectal bleeding or blood in your stool

You know your body best. It is important to speak with your care team if you experience symptoms that feel unusual to you.

Diagnosis

Sometimes neuroendocrine cancer may go undiagnosed for many years before it is found. It may also be found by accident when completing imaging or testing for another reason. Because neuroendocrine cancer is rare and challenging to diagnose, it is important to see a NEN specialist. They have the most experience diagnosing and treating neuroendocrine cancer. Your care team may use multiple types of tests to check for neuroendocrine cancer:

• Blood and urine tests: Blood and urine tests check for abnormal levels of hormones, tumor markers, or genetic traits based on medical history and physical exam.
• Imaging tests: Imaging tests look for tumors and measure their size. Some are used to monitor how well treatment works.
  • Computed tomography (CT or CAT) and magnetic resonance imaging (MRI) (with contrast dye): detailed pictures to find and measure tumors
  • Positron emission tomography (PET) or PET-CT scan: Show the location of a tumor, how active it is, and if it has spread. Note: Most NENs only appear on a special PET, called a DOTATATE PET.
• Biopsy: A small sample of tissue is removed so a pathologist can see if and what cancer cells are present. Molecular testing may be done to find specific genes, proteins, and other factors.

Staging & Grading 

Staging defines the extent to which a tumor has spread. It takes into account the tumor’s size, location, and whether or not it has spread to a lymph node or other organ.  

Neuroendocrine cancer may be: 

• Local: In one spot
• Regional: Spread to nearby tissue or lymph nodes
• Metastatic: Spread through the body to other organs (commonly to the liver, bone, or lungs) 

A tumor grade tells your care team how fast the tumor cells are dividing. A higher-grade tumor grows more quickly and might require more aggressive treatment. Both stage and grade guide your treatment options.  

Treatments & Side Effects

Many patients with neuroendocrine cancer live well for a long time with the proper treatment and side effect management. Your treatment plan will be based on: 

• Your diagnosis (NEN type, stage, grade, location of primary tumor)
• Your general health
• Your symptoms
• Your personal and treatment goals 

Speak with your care team about the best treatment options for you. With neuroendocrine cancer, there is not one right or wrong sequence for treatment. It will depend on your personal health, diagnosis, and goals. Below are the treatment options for neuroendocrine cancer.  

Managing Treatment Side Effects 

Ask your care team up front about side effects. Knowing what to expect will help you feel better prepared. It will be important for you to speak up and ask questions along the way.

Below are some common side effects from neuroendocrine cancer treatment: 

• Fever/infection  
• Fatigue
• Upset stomach/nausea, bloating
• Low blood counts
• High blood sugar levels
• Diarrhea
• Hair loss
• Skin reactions
• Pain
• Swelling
• Flushing of the face
• Appetite changes
• Anxiety or distress 

There are many ways, including medications, that your care team can recommend to help with these side effects. Receiving a cancer diagnosis and undergoing cancer treatment can be challenging for both you and your loved ones. Unwanted side effects can intensify the disruption in your life even further. 

Learn more about managing treatment side effects

Coping With Neuroendocrine Cancer

In addition to the physical side effects of treatment, it is normal to experience emotional side effects. This could include feeling anxious, worried, or overwhelmed. If you or your loved one is experiencing any of these feelings, speak with your care team. No side effect or emotion is too small to mention to your care team. They can refer you to a mental health professional who can help with navigating concerns and share ways to cope. Your care team can refer you to a social worker or patient navigator who can recommend resources and support groups. 

Keep in mind the following:

• Be open to asking your care team questions. Keep asking questions if there is something you do not understand. If you are a visual learner, ask if they can provide an image or drawing to help explain.  
• Know what signs or symptoms you should tell your care team about right away. Consider keeping a journal that lists the symptoms and side effects you experience. Be specific and note the time of day and severity.
• Focus on what you can control. Take things one small step at a time. Do not try to make changes right away.
• Be gentle with yourself when you are feeling stressed. You may feel more anxious when it gets close to a doctor’s appointment. It may help to take someone with you to be an extra set of eyes or ears during the visit.  
• Share your feelings with trusted friends, family members, a case manager or counselor, or a clergy person or spiritual advisor.
• Ask for help from friends and your community through CSC’s MyLifeLine — a free service offered by the Cancer Support Community. 

Learn more about coping with mental health concerns

Importance of Nutrition

If you experience challenges with your diet and nutrition throughout or after treatment, let your care team know. They can refer you to an oncology registered dietitian (RD). The RD can help with concerns such as:

• Managing side effects like nausea, taste changes, or weight loss
• Creating personalized meal plans based on your treatment and health needs
• Advising on safe use of supplements and vitamins 

Learn more about diet & nutrition

Managing the Cost of Cancer Treatment 

Worries about the costs of care are common when you are facing a cancer diagnosis. Learn how to talk about the financial side of cancer and where to go for help. 

Learn more about managing the costs of cancer treatment

Support for Caregivers 

The ripples of a cancer diagnosis extend to spouses, partners, siblings, children, and friends. Many family members may need to become caregivers for the first time. It is important for caregivers to also seek and receive the support they need. 

Learn more about support for caregivers

Living with neuroendocrine cancer can feel overwhelming, but you do not have to face it alone. Asking for help, sharing your concerns, and leaning on support from loved ones and patient groups can make a real difference. Speak up about your side effects and what matters most to you — your voice matters in every care decision. By asking questions and advocating for yourself, you can feel more confident and empowered as you move forward in your care.