- Disease name: Carcinoid syndrome (Carcinoid syndrome)
1) Disease description (causes and symptoms)
- Definition and causes
- Carcinoid syndrome is a syndrome caused by substances actively secreted by tumors originating from the neuroendocrine system (carcinoid tumors), such as serotonin, histamine, and calcitonin-like peptides. The primary lesions commonly occur in the gastrointestinal tract, particularly the small intestine (especially the ileum), appendix, and rectum, but can also occur in the lungs, pancreas, ovaries, and other organs. The exact cause is unknown, and it may be associated with certain genetic predispositions.
- Pathophysiology (summary)
- When serotonin and other substances secreted by the tumor enter the systemic circulation, they can cause peripheral vasodilation (flushing), increased intestinal motility (diarrhea and abdominal pain), and bronchoconstriction (asthma-like symptoms). Substances that pass through the portal vein are normally metabolized in the liver, but systemic symptoms may develop depending on liver metastasis or the tumor location. Long-term tryptophan depletion can lead to niacin deficiency (pellagra).
- Main symptoms
- Acute flushing of the face and neck
- Recurrent diarrhea and abdominal pain
- Asthma-like symptoms caused by bronchoconstriction (shortness of breath and wheezing)
- Carcinoid heart disease (mainly right-sided valvular abnormalities, including valvular disease such as tricuspid regurgitation)
- Fever, weight loss and malnutrition, skin rashes, sexual dysfunction (erectile dysfunction and decreased libido), cyanosis, and acromegaly-like features (rare)
2) Treatment methods and precautions
- Standard treatment (summary)
- When local curative treatment is possible: Surgical resection (removal of the primary lesion and any removable metastatic sites) — the extent is determined according to tumor size and the presence or absence of metastasis
- When metastatic lesions are present or complete resection is not possible: Drug therapy and systemic treatment for symptom relief
- Somatostatin analogues (Octreotide, Lanreotide): First-line drugs for relieving symptoms (flushing and diarrhea) and inhibiting tumor growth
- PRRT (peptide receptor radionuclide therapy, e.g., 177Lu-DOTATATE): Effective for tumor control when somatostatin receptors are positive
- Telotristat ethyl: Used for segmental diarrhea that is not controlled with somatostatin (a tryptophan hydroxylase inhibitor)
- Chemotherapy: Mainly used in high-grade (poorly differentiated) or rapidly progressive cases
- Targeted therapy (e.g., everolimus): Considered for certain neuroendocrine tumors
- Liver metastasis: Liver resection (when possible), hepatic arterial embolization (vascular embolization), and local liver treatments may be considered
- Carcinoid heart disease: Valve surgery (replacement or repair) may be considered when there is impaired cardiac function or symptoms
- Emergency and special management
- Carcinoid crisis (sudden worsening of acute symptoms): May be triggered by surgery, anesthesia, biopsy, chemotherapy, and other procedures — intravenous octreotide bolus and continuous infusion before surgery and during emergencies, along with supportive treatment (fluids, vasoconstrictors, etc.), are necessary
- Lifestyle management and medication-related precautions
- Avoid or be cautious of triggers that may worsen symptoms (alcohol, stress, strenuous exercise, and certain foods — including some foods such as cheese, wine, bananas, and nuts, as well as histamine-triggering foods)
- Certain medications (e.g., drugs that significantly alter cardiac contractility or vascular activity, opioids, and antidepressants) may worsen symptoms or cause interactions — consult the attending physician
- Before surgery or procedures, octreotide pretreatment may be necessary to prevent carcinoid crisis
- Risk of complications
- Carcinoid heart disease (right-sided valvular insufficiency or stenosis), dehydration, electrolyte abnormalities, and malnutrition caused by severe chronic diarrhea, niacin deficiency (pellagra), and carcinoid crisis (which may cause shock)
3) Checkpoints before an outpatient visit (items to prepare and points for medical history)
- Items to prepare
- A list of all medications currently being taken (including prescription and nonprescription medications, herbal medicines, and supplements) or medication packages
- Copies of records of previous surgeries and hospitalizations and test results (CT, MRI, blood tests, urine tests, etc.), if possible
- Symptom records: frequency, duration, and triggers of flushing, diarrhea, and shortness of breath; weight changes; and eating patterns
- Allergies and any history of abnormal reactions during previous anesthesia or surgery
- Key information to tell the doctor during the outpatient visit
- When the symptoms most recently occurred and aggravating factors (foods, medications, stress, etc.)
- Whether a neuroendocrine tumor has previously been diagnosed and treatments already received (surgery, anticancer treatment, radiation, somatostatin analogues, etc.)
- Cardiovascular symptoms (arrhythmia, shortness of breath, breathlessness during exercise, etc.)
- Example questions (questions the patient can prepare)
- "How will this medication (or injection) help my symptoms?"
- "Is surgery possible in my condition, and what are the expected benefits and risks of surgery?"
4) Examples of general questions to ask the doctor
- What is the purpose of this medication (or injection), and what effects and side effects can be expected?
- Based on my case (stage and presence or absence of metastasis), what is the standard treatment pathway? What is the expected prognosis?
- What special precautions should I take before and after surgery or a procedure?
- What lifestyle changes should I make to better manage my symptoms (flushing and diarrhea)?
- Do I need a cardiac (valvular) evaluation? Are regular echocardiograms recommended?
5) Examples of disease-specific questions
- Has my (or the patient’s) tumor been tested for somatostatin receptor positivity? Can we confirm whether PRRT (177Lu-DOTATATE) is indicated?
- I have liver metastases. Is liver resection or embolization possible, or what is the optimal approach for symptom control apart from surgery?
Reference (summary of diagnostic tests): Measurement of urinary 5-HIAA (a serotonin metabolite), plasma chromogranin A, computed tomography (CT)/MRI, somatostatin receptor imaging (68Ga-DOTATATE PET/CT or octreotide scan), endoscopic ultrasonography (to identify gastrointestinal lesions), and cardiac function evaluation (echocardiography) are used for diagnosis and staging.
(Because treatment and testing vary depending on the clinical situation, please consult the attending specialist regarding an individualized treatment plan.)