Definition

Neuroendocrine Tumors are cancers that begin in neuroendocrine cells—special cells found throughout the body that share features of both nerve cells (which help send signals) and endocrine cells (which help make hormones).

Neuroendocrine Tumors are uncommon and can develop in many places. They’re most often found in the lungs and in parts of the digestive system (such as the appendix, small intestine, rectum, and pancreas).

Some Neuroendocrine Tumors are slow-growing, while others grow more quickly. They’re also commonly described as:

• Functional (they make extra hormones and can cause hormone-related symptoms)
• Nonfunctional (they don’t make enough excess hormones to cause noticeable symptoms)

People sometimes ask whether Neuroendocrine Tumors are “the same as” adenocarcinoma. They’re not the same. Adenocarcinoma starts in gland-forming cells and often behaves differently. For example, pancreatic neuroendocrine tumors often grow more slowly than pancreatic adenocarcinoma.

Educational note: This page is for general information only and does not replace medical advice. If you have concerning symptoms, seek evaluation from a licensed clinician.

Why they happen and who is at higher risk

Causes

For many people, the exact cause isn’t known. What’s understood is that Neuroendocrine Tumors begin when neuroendocrine cells develop DNA changes that disrupt normal growth control, allowing abnormal cells to multiply and form a tumor.

Symptoms

Neuroendocrine Tumors don’t always cause symptoms early on. When symptoms happen, they often depend on where the tumor is located and whether it produces excess hormones.

General symptoms may include:

• Pain from a growing tumor
• A lump you can feel under the skin
• Feeling very tired
• Losing weight without trying

If the tumor makes excess hormones (functional tumors), symptoms may include:

• Skin flushing
• Diarrhea
• Increased thirst
• Dizziness
• Shakiness
• Skin rash

When to seek medical care

• Make an appointment with a licensed clinician if you have symptoms that worry you or persist.
• Seek urgent care if symptoms are severe, rapidly worsening, or include dehydration, severe weakness, confusion, or fainting.

How Neuroendocrine Tumors are found and confirmed

Diagnosis

Diagnosis and staging can vary by tumor type and location, but common steps include a clinical evaluation plus testing to confirm what the tumor is and how it behaves.

Common diagnostic steps may include:

• History and physical exam
• Blood tests (including blood chemistry testing in many evaluations)
• Imaging tests to locate and assess tumors, such as:
  • CT scan
  • MRI
  • PET scan
  • Ultrasound
• Biopsy, where a tissue sample is examined to confirm the diagnosis and tumor features

Because Neuroendocrine Tumors can behave very differently depending on grade, location, and spread, clinicians often use these results to plan next steps.

Medications and treatment approaches

Medications

Medication options depend on tumor type, location, grade, and whether the tumor is functional.

Common medication categories used in care plans can include:

• Hormone-targeting medicines for symptom control in some functional tumors (for example, somatostatin analogs such as octreotide or lanreotide)
• Chemotherapy medicines in selected situations (more common in higher-grade or fast-growing disease patterns)
• Other systemic medicines may be used depending on the subtype and clinical scenario (your oncology team determines what fits your case).

Treatments

Treatment plans are individualized. A person may receive one approach or a combination.

Common treatment pathways can include:

• Surgery (when the tumor can be removed safely)
• Radiation therapy (in selected cases)
• Chemotherapy (in selected cases)
• Hormone therapy for symptom control in some functional tumors (including somatostatin analog approaches)
• Other targeted procedures may be used depending on the situation (for example, therapies that treat liver tumors if spread occurs there)

Only a licensed medical team can recommend the right plan for your specific diagnosis.

FAQs people actually ask

FAQs

How do I know if I might have a Neuroendocrine Tumor?

Many people have no symptoms early. Others notice ongoing issues like unexplained fatigue, weight loss, persistent pain, or hormone-type symptoms (flushing or diarrhea). The only way to know is to get evaluated and, when appropriate, have imaging and/or a biopsy.

Are Neuroendocrine Tumors always aggressive?

No. Some Neuroendocrine Tumors grow slowly, while others grow faster. “How aggressive” depends on the tumor’s grade, location, and whether it has spread.

What’s the difference between functional and nonfunctional Neuroendocrine Tumors?

Functional Neuroendocrine Tumors can make excess hormones and cause symptoms like flushing or diarrhea. Nonfunctional tumors usually don’t release enough hormones to cause noticeable hormone symptoms, so they may be found later or incidentally.

What tests are commonly used to diagnose Neuroendocrine Tumors?

Often a combination of imaging (CT/MRI/PET/ultrasound), blood testing, and biopsy to confirm the diagnosis and guide treatment planning.

If I already have prescriptions, what should I keep in mind when planning for affordability?

If you already have a clinician-guided plan and valid prescriptions, focus on safety-first verification and continuity of care. Start with our Certified Medical Tourism Professional guide and our overview of Pharmacies in Tijuana (2025).

References and further reading

References

NCBI Bookshelf (StatPearls) — Multiple Endocrine Neoplasia Type 1 (MEN1): Clinical summary

National Cancer Institute (NCI) — Gastrointestinal Neuroendocrine Tumors Treatment (PDQ)

NCI / NCBI Bookshelf (Genetics) — Multiple Endocrine Neoplasia Type 1 (MEN1): Tumor types overview