Gastrointestinal Neuroendocrine Tumors (GI NET): Symptoms, Causes, Treatment

What are the symptoms of gastrointestinal neuroendocrine tumors?

Gastrointestinal neuroendocrine tumors (NETs) can present with various symptoms, depending on their location, size, and whether they produce hormones. Common symptoms may include:

Abdominal pain or discomfort
Changes in bowel habits, such as diarrhea, constipation, or bowel obstruction
Rectal bleeding or blood in the stool
Unexplained weight loss
Fatigue
Nausea and vomiting
Jaundice (yellowing of the skin and eyes) if the tumor affects the liver or bile ducts
Symptoms related to hormone production, such as flushing, wheezing, rapid heartbeat, low blood sugar (hypoglycemia), or changes in blood pressure

Since these symptoms can be nonspecific and overlap with other gastrointestinal conditions, it’s essential to consult a healthcare professional for proper evaluation and diagnosis if you’re experiencing any concerning symptoms.

What are the causes of gastrointestinal neuroendocrine tumors?

The exact causes of gastrointestinal neuroendocrine tumors (NETs) are not fully understood, but several factors may contribute to their development:

Genetic mutations: Inherited genetic syndromes such as multiple endocrine neoplasia type 1 (MEN1), neurofibromatosis type 1 (NF1), and von Hippel-Lindau disease (VHL) are associated with an increased risk of developing NETs.
Sporadic mutations: Acquired mutations in certain genes, such as those involved in cell growth regulation and tumor suppression (e.g., MEN1, DAXX, ATRX), can lead to the development of gastrointestinal NETs.
Exposure to certain substances: Prolonged exposure to certain substances or environmental factors, such as tobacco smoke, alcohol, or certain chemicals, may increase the risk of developing gastrointestinal NETs.
Chronic inflammation: Conditions associated with chronic inflammation of the gastrointestinal tract, such as inflammatory bowel disease (IBD), may predispose individuals to the development of NETs.
Unknown factors: In many cases, the exact cause of gastrointestinal NETs remains unknown, and they may develop sporadically without a clear predisposing factor.

It’s important to note that while these factors may increase the risk of developing gastrointestinal NETs, not everyone with these risk factors will develop the condition, and some individuals may develop NETs without any identifiable risk factors. Regular screening and early detection can help in managing and treating gastrointestinal NETs effectively.

How is the diagnosis of a gastrointestinal neuroendocrine tumor made?

The diagnosis of a gastrointestinal neuroendocrine tumor (GEP-NET) typically involves a combination of clinical evaluation, imaging studies, and laboratory tests. Here are the steps involved in diagnosing a GEP-NET:

Symptom evaluation: Patients with suspected GEP-NET typically present with symptoms such as abdominal pain, diarrhea, constipation, weight loss, or flushing due to hormone production.
Physical examination: A thorough physical examination is performed to assess for any abdominal masses or other signs of disease.
Imaging studies: The following imaging studies are commonly used to diagnose GEP-NETs:
- Computed tomography (CT) scan: A CT scan uses X-rays and computer technology to produce detailed images of the internal organs and tissues.
- Magnetic resonance imaging (MRI): An MRI uses a strong magnetic field and radio waves to produce detailed images of the internal organs and tissues.
- Endoscopic ultrasound (EUS): EUS is a minimally invasive procedure that uses an endoscope with a built-in ultrasound probe to visualize the internal organs and tissues.
- Octreoscan (In-111 octreotide scan): This is a nuclear medicine imaging test that uses a small amount of radioactive material to visualize the pancreas and other organs.
Blood tests: Blood tests are used to measure hormone levels, such as:
- Chromogranin A (CgA): Elevated levels of CgA can indicate the presence of a GEP-NET.
- Gastrin: Elevated levels of gastrin can indicate the presence of a gastrinoma (gastrin-producing pancreatic neuroendocrine tumor).
- Insulin: Elevated levels of insulin can indicate the presence of an insulinoma (insulin-producing pancreatic neuroendocrine tumor).
- Glucagon: Elevated levels of glucagon can indicate the presence of a glucagonoma (glucagon-producing pancreatic neuroendocrine tumor).
Biopsy: A biopsy may be performed to confirm the diagnosis and obtain tissue for histopathological examination. This is usually done using endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) or surgical resection.
Pathological examination: The biopsy specimen is examined under a microscope by a pathologist to determine the type of tumor and its grade (low-grade or high-grade).
Molecular testing: Genetic testing may be performed to identify genetic mutations associated with GEP-NETs, such as MEN1, VHL, and PRKAR1A.

In summary, the diagnosis of GEP-NETs involves a combination of clinical evaluation, imaging studies, blood tests, biopsy, pathological examination, and molecular testing. The specific diagnostic approach may vary depending on the patient’s symptoms and clinical presentation.

What is the treatment for a gastrointestinal neuroendocrine tumor?

The treatment for gastrointestinal neuroendocrine tumors (GEP-NETs) depends on the type and stage of the tumor, as well as the patient’s overall health. The primary treatment options for GEP-NETs include:

Surgery: Surgery is often the primary treatment for GEP-NETs, particularly for patients with localized tumors. The goal of surgery is to remove the tumor and any affected lymph nodes.
Peptide receptor radionuclide therapy (PRRT): PRRT is a type of targeted radiation therapy that uses small amounts of radioactive material to target and destroy cancer cells. It is often used in combination with surgery or chemotherapy.
Chemotherapy: Chemotherapy may be used to treat advanced or metastatic GEP-NETs that cannot be surgically removed. The most commonly used chemotherapy regimens for GEP-NETs include streptozotocin, doxorubicin, and 5-fluorouracil.
Somatostatin analogues: Somatostatin analogues, such as octreotide and lanreotide, are medications that can help reduce symptoms caused by excess hormone production from the tumor. They can also help slow down tumor growth.
Everolimus: Everolimus is a medication that inhibits mTOR, a protein that promotes tumor growth. It is often used in combination with somatostatin analogues to treat advanced GEP-NETs.
Sunitinib: Sunitinib is a tyrosine kinase inhibitor that targets the VEGF receptor and can be used to treat advanced GEP-NETs.
Liver-directed therapies: For GEP-NETs that have metastasized to the liver, liver-directed therapies such as radiofrequency ablation, chemoembolization, or cryotherapy may be used.
Targeted therapy: Targeted therapy, such as telotristat ethyl, can be used to treat carcinoid syndrome symptoms caused by excessive serotonin production from the tumor.

The choice of treatment depends on various factors, including the size and location of the tumor, the patient’s age and overall health, and the presence of any symptoms.

In addition to these treatments, patients with GEP-NETs may also receive supportive care to manage symptoms such as diarrhea, flushing, and abdominal pain. This may include medications to control nausea and vomiting, antibiotics to prevent infections, and pain management medications.

It’s important to note that GEP-NETs are often slow-growing tumors, and treatment may not always be necessary. Patients with small tumors that are not causing symptoms may be monitored closely with imaging tests and blood tests to monitor for any changes.

Patients should discuss their treatment options with their healthcare provider to determine the best course of treatment for their individual situation.

What is the survival rate for gastrointestinal neuroendocrine tumors?

The survival rate for gastrointestinal neuroendocrine tumors (GEP-NETs) varies depending on the type of tumor, its stage, and the patient’s overall health.

According to the National Cancer Institute, the 5-year survival rate for patients with GEP-NETs is as follows:

For patients with localized GEP-NETs (tumors that are confined to the primary site), the 5-year survival rate is around 70-90%.
For patients with regional GEP-NETs (tumors that have spread to nearby lymph nodes or tissues), the 5-year survival rate is around 50-70%.
For patients with distant metastatic GEP-NETs (tumors that have spread to distant parts of the body), the 5-year survival rate is around 20-40%.

It’s important to note that these survival rates are based on data from large groups of patients and should not be taken as a guarantee of outcome for an individual patient.

In general, the prognosis for GEP-NETs is better if:

The tumor is diagnosed at an early stage, when it is still localized and has not spread.
The tumor is small and has not grown aggressively.
The patient’s overall health is good.
The patient receives effective treatment, including surgery, chemotherapy, and targeted therapy.

On the other hand, the prognosis may be worse if:

The tumor is diagnosed at a late stage, when it has spread to other parts of the body.
The tumor is large and has grown aggressively.
The patient has comorbidities or other health conditions that affect their ability to tolerate treatment.
The patient does not receive timely and effective treatment.

It’s important for patients with GEP-NETs to work closely with their healthcare provider to determine the best course of treatment and to monitor their response to treatment.