Carcinoid Syndrome

Carcinoid syndrome is a rare condition caused by certain slow-growing cancers called carcinoid tumors (neuroendocrine tumors). These tumors release excess hormones into your bloodstream, leading to a group of symptoms like skin flushing, diarrhea, and breathing difficulties. It often occurs when tumors have spread or are in locations where hormones bypass the liver's filtering system.

What is Carcinoid Syndrome?

Carcinoid syndrome is a rare set of symptoms that happens when certain slow-growing cancers, called carcinoid tumors (neuroendocrine tumors), release large amounts of hormones into your body. These tumors most commonly start in the digestive tract or lungs. The syndrome develops when these hormones are not filtered by the liver, causing symptoms like flushing and diarrhea.

Carcinoid syndrome is a collection of symptoms. It is not the cancer itself. These symptoms result from hormones produced by carcinoid tumors. These tumors are a type of neuroendocrine tumor. This means they come from cells that act like both nerve cells and hormone-producing cells. They can grow in many body parts. Most often, they are found in the small intestine, appendix, colon, or lungs. The tumors release hormones like serotonin, bradykinin, histamine, and prostaglandins. Normally, your liver filters these hormones from your blood. This happens if the tumor is in your digestive tract. The liver stops them from causing widespread symptoms. But if the tumors spread to the liver, or are in the lungs or ovaries, the hormones bypass the liver. They then circulate throughout your body. This leads to carcinoid syndrome.

Symptoms

The symptoms of carcinoid syndrome can vary but commonly include sudden skin flushing, frequent watery diarrhea, and breathing difficulties like wheezing. Some people may also experience rapid heart rate or, in severe cases, heart valve damage. These symptoms occur because of the excess hormones circulating in the bloodstream.

The most common symptom is flushing. This is a sudden feeling of warmth and redness. It usually appears on your face, neck, and upper chest. Flushing can last for minutes or several hours. Stress, alcohol, exercise, or certain foods like spicy dishes or cheese can trigger it. Over time, your skin in these areas might become permanently reddish or purplish. Another frequent symptom is diarrhea. This often means frequent, watery stools and abdominal cramps. Some people also experience asthma-like symptoms. These include wheezing and shortness of breath. Less common symptoms can be a rapid heart rate (tachycardia) and low blood pressure (hypotension). In some cases, excess hormones can harm your heart. This condition is called carcinoid heart disease. It causes the heart valves, especially on the right side, to thicken and get damaged. This can lead to heart failure symptoms. These include fatigue, shortness of breath, and swelling in your legs and ankles. Rarely, a condition called pellagra can develop. This happens because your body uses up a nutrient called tryptophan to make serotonin. Pellagra causes skin rashes, diarrhea, and confusion.

Causes & risk factors

Carcinoid syndrome is caused by carcinoid tumors (neuroendocrine tumors) that produce and release excessive amounts of hormones into the bloodstream. These tumors are the direct cause of the syndrome, rather than external risk factors. The syndrome typically develops when these tumors have spread to the liver or are located in organs like the lungs, allowing hormones to bypass the liver's filtering action.

The underlying cause of carcinoid syndrome is the presence of carcinoid tumors. These are a type of slow-growing cancer. These tumors come from neuroendocrine cells. These cells are found throughout the body. They can produce and release hormones. When these tumors grow, they can secrete large amounts of hormones. Examples include serotonin, bradykinin, and histamine. Normally, the liver acts as a filter for substances in the blood. If a carcinoid tumor is in the digestive system, the hormones it releases usually pass through the liver. The liver neutralizes them. This happens before they can cause widespread symptoms. However, if the tumors have spread to the liver (metastasized), or if the primary tumor is in a location like the lungs or ovaries, the hormones can enter the general circulation. They do this without being filtered. This allows the hormones to reach various parts of the body. This then triggers the symptoms of carcinoid syndrome. There are no specific lifestyle or environmental risk factors identified for developing carcinoid syndrome itself, beyond the presence of these specific tumors.

How it's diagnosed

Diagnosing carcinoid syndrome involves reviewing your symptoms, conducting physical exams, and performing specific tests to detect excess hormones and locate tumors. A common test is a 24-hour urine collection to measure a serotonin breakdown product. Blood tests and various imaging scans are also used to confirm the presence of carcinoid tumors and their spread.

Your doctor will start by asking about your symptoms and medical history. This is followed by a physical examination. To confirm excess hormones, a key diagnostic test is a 24-hour urine collection. This measures levels of 5-hydroxyindoleacetic acid (5-HIAA). This substance is a breakdown product of serotonin. Serotonin is one of the main hormones released by carcinoid tumors. Before this test, you may need to avoid certain foods. These include bananas, avocados, pineapples, and walnuts. You may also need to avoid some medications. These can interfere with the results. Blood tests may also be done. They check for high levels of chromogranin A (CgA) and serotonin. These markers can show if neuroendocrine tumors are present. Once hormone levels suggest carcinoid syndrome, imaging tests are used. These tests find the primary tumor and check if it has spread. Imaging can include computed tomography (CT) scans and magnetic resonance imaging (MRI). Specialized nuclear medicine scans are also used. Examples are an octreotide scan (somatostatin receptor scintigraphy) or a positron emission tomography (PET) scan. Finally, a definitive diagnosis often needs a biopsy. A small tissue sample from the suspected tumor is removed. It is then examined under a microscope. This helps confirm the type of tumor. It also guides treatment decisions. In some cases, endoscopy or bronchoscopy might be used. These procedures help visualize and biopsy tumors in the digestive tract or lungs.

Treatment options

Treatment for carcinoid syndrome focuses on managing symptoms and treating the underlying carcinoid tumors. Symptom relief often involves medications that block hormone release or production, such as somatostatin analogs. Tumor treatment can include surgery to remove the tumor, chemotherapy, radiation, or targeted therapies, depending on the tumor's location and whether it has spread.

The main goal of treatment is to reduce the symptoms of carcinoid syndrome. It also aims to control the growth and spread of the carcinoid tumors. If the tumor is localized and can be safely removed, surgery is often the best treatment. Removing the tumor can greatly reduce hormone production. This helps ease symptoms. For tumors that have spread, especially to the liver, other procedures may be used. These include radiofrequency ablation, hepatic artery embolization, or cryoablation. These methods destroy or block blood supply to the tumors. Medications are often used to manage symptoms caused by excess hormones. Somatostatin analogs, such as octreotide or lanreotide, are commonly given as injections. These drugs act like a natural hormone. They help block the release of other hormones from the tumor. This effectively reduces flushing and diarrhea. Another medication, telotristat ethyl, is an oral drug. It specifically blocks the production of serotonin. This further helps control severe diarrhea. Other treatments for the tumor itself may include chemotherapy or radiation therapy. Targeted drug therapies like everolimus or sunitinib may also be used. These drugs interfere with specific pathways involved in cancer growth. For patients who develop carcinoid heart disease, surgery to repair or replace damaged heart valves may be needed. Niacin supplements can be prescribed if pellagra develops due to serotonin overproduction. Your doctor will create a treatment plan based on your specific condition, tumor characteristics, and how severe your symptoms are.

Recovery & outlook

The recovery and outlook for people with carcinoid syndrome vary widely, depending on the tumor's location, stage, and how well it responds to treatment. Carcinoid tumors are often slow-growing, which can lead to a longer life expectancy compared to many other cancers. Treatment aims to control symptoms and tumor growth, improving quality of life.

Carcinoid tumors are generally slow-growing cancers. This often leads to a more favorable outlook. This is compared to many faster-growing cancers. However, the prognosis largely depends on whether the tumor has spread (metastasized) and how much it has spread. If the tumor is found early and can be completely removed with surgery, the chances of a good outcome are higher. Even when the tumor has spread, treatments are available. These treatments manage symptoms and slow tumor progression. Many people with carcinoid syndrome can live for many years with effective management. Regular follow-up appointments and ongoing treatment are very important. They help monitor the tumor's behavior and adjust therapies as needed. Carcinoid syndrome can affect daily life. Symptoms like flushing and diarrhea can be challenging. However, modern treatments are often very effective at controlling these issues. This improves a person's quality of life. It is important to work closely with your healthcare team. Together, you can develop a personalized treatment and management plan.

When to see a doctor

You should see a doctor if you experience symptoms that could indicate carcinoid syndrome, especially persistent flushing, chronic diarrhea, or unexplained wheezing. Early diagnosis and treatment are important for managing the condition and improving your outlook. Do not wait if you notice these symptoms developing or worsening.

It is important to contact your doctor if you develop any signs or symptoms that might suggest carcinoid syndrome. These include: * Frequent, unexplained episodes of skin flushing. This is especially true on your face, neck, and upper chest. * Chronic, watery diarrhea along with abdominal cramps. * New or worsening asthma-like symptoms. These include wheezing or shortness of breath, without a clear cause. While these symptoms can be caused by many different conditions, it is crucial to have them evaluated by a healthcare professional. Early diagnosis of carcinoid syndrome and its underlying tumors allows for timely treatment. This can help manage symptoms, slow tumor growth, and prevent complications like carcinoid heart disease. If you experience severe chest pain, sudden severe shortness of breath, or signs of severe dehydration from diarrhea, seek immediate medical attention.

Frequently asked questions

Can diet affect carcinoid syndrome symptoms?

Yes, certain foods and drinks can sometimes trigger or worsen symptoms like flushing and diarrhea in people with carcinoid syndrome. Common triggers include alcohol, spicy foods, and foods high in tyramine (like aged cheeses). Your doctor or a dietitian can help you identify and manage dietary triggers.

Is carcinoid syndrome a type of cancer?

Carcinoid syndrome is a collection of symptoms caused by carcinoid tumors, which are a type of slow-growing cancer (neuroendocrine tumor). So, while the syndrome itself isn't cancer, it is a direct result of the hormones produced by these cancerous tumors.

How rare is carcinoid syndrome?

Carcinoid syndrome is considered rare. The underlying carcinoid tumors are also rare, often growing slowly and sometimes not causing symptoms until they are advanced or have spread.

Can carcinoid syndrome be cured?

A cure for carcinoid syndrome depends on the underlying tumor. If the tumor is localized and can be completely removed surgically, it may be cured. However, if the tumor has spread, treatment focuses on managing symptoms and controlling tumor growth and spread, rather than a complete cure.

What is a "carcinoid crisis"?

A carcinoid crisis is a rare, severe, and potentially life-threatening worsening of carcinoid syndrome symptoms. It involves intense flushing, severe low blood pressure, rapid heart rate, and breathing difficulties. It can be triggered by stress, surgery, or certain medications, and requires immediate medical attention.

Are there any lifestyle changes that can help manage carcinoid syndrome?

While lifestyle changes cannot cure carcinoid syndrome, they can help manage symptoms. Avoiding known triggers for flushing and diarrhea (like alcohol, certain foods, or stress) can be beneficial. Regular, gentle exercise and stress-reduction techniques may also help improve overall well-being. Always discuss any lifestyle changes with your doctor.

Sources

• MedlinePlus — Carcinoid Syndrome
• Mayo Clinic — Carcinoid Syndrome
• Cochrane Library — Carcinoid Syndrome