GI Neuroendocrine Tumors

Every year, health care providers diagnose about 8,000 adults in the United States with gastrointestinal neuroendocrine tumors. These kinds of cancers grow from hormone-producing cells in the digestive system. 

If a health care provider has diagnosed you with one of these conditions, you are not alone. If you think you may have a neuroendocrine tumor, there are plenty of resources for you to turn to.

Neuroendocrine tumors (NETs) are also known as neuroendocrine cancers, and were previously referred to as carcinoid tumors. Neuroendocrine tumors can grow anywhere in your body where there are hormone-producing, or neuroendocrine cells. Most of these tumors form in the digestive (gastrointestinal or GI) tract. This is likely because there are more neuroendocrine cells in your gastrointestinal tract than anywhere else in the body.

Here's where GI neuroendocrine tumors are most often found:

• Small intestine

• Appendix

• Rectum

• Colon

• Stomach

• Esophagus

• Pancreas

• Liver

For example, patients with pancreatic neuroendocrine tumors have tumors on the islet cells of the pancreas. This affects insulin and glucose levels in the body.

You may hear healthcare professionals refer to neuroendocrine tumors as neuroendocrine cancers or carcinoid tumors. All of these terms refer to the same group of conditions.

GI neuroendocrine tumors are ordered into several categories. 

However, there are two categories that you may be the most worried about, and these categories apply to conditions based on how fast the cancer spreads: GI small cell carcinoma and GI large cell carcinoma.

Both of these cancers are aggressive and account for a small proportion of all GI neuroendocrine cancers. Large cell neuroendocrine cancers are the fastest-growing between the two.

There is not a definitive cause for these kinds of tumors.

In general, cancerous cells grow after mutations occur in the DNA. Cancer-causing mutations make cells immortal— in other words, the cells fail to die when they normally would, and they continue growing and dividing.

As these cells accumulate, they form a cancerous tumor, and those cells can invade healthy tissues that lie nearby the original site of cancer growth. Over time, the cancer can spread all over the body.

Physicians and scientists aren't sure about the exact causes of neuroendocrine tumors, but, they do know that these kinds of tumors come from cancer cells that grow in neuroendocrine cells.

In many cases, GI neuroendocrine tumors are nonfunctional and do not cause symptoms, which means the tumors do not make hormones and other chemicals. They might be found during a routine exam, or when an exam or surgery is being performed for another health issue.

In other cases, the symptoms of neuroendocrine tumors in the GI tract are closely related to the functions of the digestive system. Since the cancerous cells can cause a disruption in the body's normal functioning, patients with neuroendocrine cancer may experience the following symptoms:

• Belly (abdominal) pain or pressure.

• Change in bowel habits.

• Diarrhea.

• Bowel obstruction/blockage.

• Bloody bowel movements.

• Rectal pain.

• Rectal bleeding.

• Nausea and vomiting.

• No desire to eat.

• Feeling tired all the time (fatigue).

• Weight loss.

• A lump or tumor you can feel.

• Chest pain.

• Shortness of breath.

• Skin flushing around the face and neck.

If you notice any of these symptoms, you should talk with your primary health care provider as soon as possible. They can help you get the testing you need to determine whether you have a GI neuroendocrine tumor or another condition related to these symptoms.

Like other kinds of cancers, there are a few risk factors for GI neuroendocrine tumors that you should keep in mind. Here are the top five:

1. Older age. Older adults are more likely to develop gastrointestinal tumors. Their DNA is more likely to experience the mutations that lead to neuroendocrine cancer.
2. Gender. Statistically, women are more likely to develop GI neuroendocrine tumors than men. 
3. Family history. Your family history can influence whether you develop a neuroendocrine tumor. Specifically, a family history of multiple endocrine neoplasias can increase the risk of developing neuroendocrine tumors in your GI tract. 
4. Preexisting Conditions. People with diseases that damage the stomach and reduce acid production have a greater risk of developing stomach neuroendocrine tumors. 
5. Pernicious Anemia. People with pernicious anemia have a higher risk of developing stomach neuroendocrine tumors

If you see your primary health care provider about your symptoms, it's likely that they  will run a wide range of diagnostic tests to determine what the cause of your symptoms is.

Tests and Screenings for GI Neuroendocrine Tumors

These tests may be used to help diagnose GI neuroendocrine tumors:

• X-rays and scans. Chest X-ray, CT scan and MRI scans are all useful in diagnosis. These imaging tests can show the location of the tumor, how big the tumor is and if it has spread.

• Octreotide scan or DOTATATE scan. This special scan is commonly used to find neuroendocrine tumors. It uses a medicine called octreotide (and now, a newer medicine called DOTATATE) that's attached to a radioactive tracer. Octreotide/DOTATATE is a hormone-like medicine that binds to neuroendocrine cells. It's put into the blood through a vein in the hand or arm, and over time, it attaches to the tumor cells. Then scans are done over the next few days, and they show where the radioactive tracer has collected.

• Exam and biopsy. A surgical procedure may be needed to take out a tiny sample of tissue from the tumor. This process is called a biopsy, and the sample is sent to a lab and tested for cancer cells.

• Urine test. If you have a tumor that's making too much of the hormone serotonin, it might show up as an acid in your urine called 5-HIAA, or5-hydroxyindoleacetic acid.
• Blood test. A blood test might be done to check for increased levels of hormones or other substances, like serotonin, chromogranin A (CgA) and gastrin, amongst others.. The blood tests may or may not be needed, depending on where the tumor is.

The way that your physician treats your neuroendocrine tumor(s) will depend on the type, location and severity of the tumor. Your physician will also consider your overall health and personal preferences.

There are a variety of treatments for GI neuroendocrine tumors. Here are some treatments that may be used:

• Surgery or Partial surgery. If your physician found the tumor early, they may be able to completely remove it. If a tumor is too big to take it all out, surgery may be used to remove part of it to suppress symptoms so that other treatments may work better.

• Chemotherapy. Medicines that kill or slow the growth of neuroendocrine tumor cells may be administered into your bloodstream or taken by mouth. Many times, several of these medicines are given together. If a tumor has spread into your liver, chemotherapy may be injected right into your liver, or small pellets may be injected into blood vessels in the liver to block blood flow to the tumor cells.

• Targeted therapy. These medicines act on certain genes or proteins that help cancer cells grow while limiting damage to healthy cells. They might be used to treat certain advanced tumors.

• Immunotherapy. This medicine treatment helps your immune system better fight cancer.

• Somatostatin analogs. Octreotide and lanreotide are medicines that are given as a shot. These medications work by blocking the overproduction of hormones caused by the cancer, which reduce the symptoms of a neuroendocrine tumor. They may also slow tumor growth.

• Peptide Receptor Radionuclide Therapy (PPRT). This treatment is with a radioactive medicine that binds to receptors on some kinds of tumors. After binding to the cancer cells, the radiation damages them. This treatment might be used if the somatostatin analogs stop working.

Talk with your healthcare providers about your treatment options. Make a list of questions. Think about the benefits and possible side effects of each option. Discuss your concerns with your healthcare provider before deciding

The five-year survival rate for people with a GI neuroendocrine tumor is 97%. Once the tumor starts spreading to nearby areas, that outlook becomes 95%, and if the tumor spreads to distant sites, the survival rate drops to 67%.

Every person who receives a cancer diagnosis develops their own way of coping, but, there are a few common strategies you can use to manage the emotions that come with your diagnosis.

First, you should conduct your own research about your condition. The best way to do this is by asking your health care team for more information.

Another way to cope with the diagnosis is by talking to others who have cancer. You can join a support group online or in person. There are plenty of options for patients of different ages, locations and conditions. The University of Cincinnati Cancer Center offers supportive services and programs for your cancer journey – explore them here. 

It may help to find control where you can. There are only so many things you can control when it comes to your cancer diagnosis, so you should take steps to maintain your health in other ways, such as through exercise and nutrition.

Your healthcare provider will talk with you about when to call. You may be told to call if you have any of the below:

• New symptoms or symptoms that get worse.

• Signs of an infection, such as a fever.

• Side effects of treatment that affect your daily function or don't get better with treatment.

Ask your healthcare provider what signs to watch for, and when to call. Know how to get help after office hours and on weekends and holidays.

The University of Cincinnati Cancer Center focuses on multidisciplinary care of cancer – meaning various experts involved in the treatment of your cancer will work together, review your case at tumor boards, see you and communicate regularly about your condition, treatment plan and progress. These include oncologists, surgeons, radiation oncologists and gastroenterologists, amongst others . Other specialists such as radiologists and pathologists provide important support to the treating physicians to diagnose and monitor the cancer.

Among our physicians are many others who make our cancer care possible – nurses, pharmacists, nutritionists, dietitians and social workers to name a few.

We also offer minimally invasive and robotic surgeries, advanced endoscopic methods of removing very early tumors, proton radiation therapy and leading-edge clinical trials of new cancer medications

The University of Cincinnati Cancer Center is always working to improve cancer treatments. This is done through clinical trials exploring new medications, methods of doing surgery or radiation and ways of minimizing side-effects from treatment.