Definition and Overview

Carcinoid cancer is an abnormal neuroendocrine growth that most commonly develops in the gastrointestinal tract. However, it can also occur in other parts of the body such as the lungs, ovaries, or testicles. Those found in the GI tract are further classified based on their specific location. These include:

  • Foregut carcinoid tumour - Grows on the lungs, stomach, and pancreas

  • Midgut carcinoid tumour - Found on the second part of the duodenum as well as in the jejunum, ileum, and right colon

  • Hindgut carcinoid tumour - Found on transverse and descending colon as well as the rectum

A carcinoid tumour is malignant but slow-growing. In its early stages, it does not cause symptoms, which unfortunately results in delayed detection and diagnosis.

Causes of Condition

Just like other types of cancers (e.g., melanoma and sarcoma), carcinoid tumour is also caused by genetic mutations in the cells' DNA. Such mutations cause the cell to grow and divide abnormally, preventing them from dying at the end of their life span. This results in the formation of abnormal growths in various locations in the body. Unless detected and treated during the early stages of the condition, these tumours can invade healthy tissues and even distant organs.

In the case of carcinoid tumours, the genetic mutations affect the neuroendocrine cells. These cells are found in various organs in the body and perform nerve cell functions as well as some endocrine cell functions. Some of the hormones they produce include cortisol, insulin, serotonin, and histamine, among others.

The risk of neuroendocrine tumours is higher among:

  1. Older individuals

  2. Those with a family history of multiple endocrine neoplasia type 1 (MEN 1)

  3. Females

  4. Those with a history of neurofibromatosis type 1

  5. Those with an existing condition, such as:

  • Pernicious anemia

  • Zollinger-Ellison syndrome

Key Symptoms

Carcinoid tumour cancer symptoms are mostly the effects of the hormones released by the tumour. These include:

  • Cutaneous flushing, or flushed skin especially in the head and neck accompanied by a warm sensation, itching, and palpitation

  • Oedema

  • Salivation

  • Upper body erythema

  • Chronic diarrhea

  • Malabsorption

  • Breathing difficulties

However, these symptoms often do not present in the early stages of the disease. When they do appear, they are often misdiagnosed as relating to other conditions. The symptoms may also vary depending on the tumour's location. For example, a carcinoid tumour in the GI tract can cause the following symptoms:

  • Nausea

  • Vomiting

  • Rectal pain and bleeding

  • Abdominal pain

  • Bowel obstruction

On the other hand, carcinoid cancer of the lungs can cause the following symptoms:

  • Chest pain

  • Cough

  • Asthma-like syndrome

  • Wheezing

  • Shortness of breath

  • Weight gain

  • Pink or purple skin marks that resemble stretch marks

Carcinoid tumours in the lungs can also cause the body to produce too much cortisol, which then leads to the development of Cushing’s syndrome.

Carcinoid tumours can also produce hormones that cause the valves, blood vessels, and the heart chamber linings to thicken. This can result in various cardiovascular problems, such as:

  • Leaky heart valves

  • Valvular heart lesions

  • Fibrosis of endocardium

These problems, collectively known as carcinoid heart disease, can result in heart failure and may necessitate valve-replacement surgery as well as other cardiovascular treatments.

Due to these factors, diagnosing as well as treating carcinoid tumours can be very challenging. Doctors usually need to perform a series of tests listed below to arrive at a definitive diagnosis.

  • Biopsy

  • Computerised tomography (CT) scan

  • Endoscopy

  • Magnetic resonance imaging (MRI)

  • Octreotide scan

  • Positron emission tomography (PET) scan

  • Upper endoscopy, colonoscopy, or capsule endoscopy. A capsule endoscopy is a modified version of an endoscopy. During the test, the patient swallows a pill with a tiny camera, allowing the doctor to see the inside of the body without having to insert a tube or an endoscope.

Who to See and Types of Treatments Available

There are a number of therapies that can be performed for the treatment of carcinoid tumours. Doctors choose the most appropriate for individual patients based on the following factors:

  • The tumour's location

  • Symptoms being experienced by the patient

  • Types of hormones being secreted by the carcinoid tumour

  • Whether the tumour has spread to other body parts

  • The patient’s preferences

Carcinoid tumours are commonly treated with a combination of surgery and systemic therapy. Whenever possible, the primary course of treatment is the surgical removal of the tumour. Some tumours, especially those detected in the early stages of the condition, are usually removed in their entirety. Some, however, like those that have already spread to other parts of the body prior to diagnosis, can be difficult to remove completely. In such cases, the surgeon will remove as much of the tumour as possible.

After surgery, patients diagnosed with carcinoid cancer have to take medications to control the symptoms of carcinoid syndrome. These include:

  • Hormone-blocking medications – Drugs that keep cancer cells from producing hormones including octreotide and lanreotide.

  • Immune-boosting medications – Drugs that stimulate the immune system so it can attack the tumour; these are very effective in further slowing down the growth of tumours.

Both types of medications can significantly reduce patients’ symptoms and are usually sufficient for patients with small, localised carcinoid tumours.

However, for patients whose tumours have spread to the liver, treatment may also involve:

  • Hepatic artery embolisation – Aims to block the blood supply to the tumours

  • Radiofrequency ablation - Aims to kill cancer cells using extreme heat

  • Cryoablation - Kills cancer cells by freezing them

  • Liver surgery - The surgical removal of the part of the liver where the tumour is located

Cancer patients generally also undergo chemotherapy or radiation therapy to make sure all cancer cells in the body are destroyed.

The various treatments required by patients with carcinoid tumours are carried out by and under the supervision of a multidisciplinary team of doctors composed of:

  • Endocrinologists

  • Gastroenterologists (for carcinoid tumours in the abdominal organs)

  • Hepatologists (for carcinoid tumours that have metastasised to the liver)

  • Medical oncologists

  • General surgeons

  • Pulmonary specialists (for carcinoid tumours in the lungs)

  • Critical care specialists

  • Radiologists (for patients who will undergo radiotherapy)

References:

  • Kulke MH, Mayer RJ. “Carcinoid tumours.” N Engl J Med 1999; 340:858-868. http://www.nejm.org/doi/full/10.1056/NEJM199903183401107

  • Van Sickle DG. “Carcinoid tumours.” Cleveland Clinic Journal of Medicine. 1972 April; 39(2): 79-86. http://www.mdedge.com/ccjm/article/90804/carcinoid-tumours

  • Modlin IM, Moss SF, Oberg K, et al. “Gastrointestinal neuroendocrine (carcinoid) tumours: current diagnosis and management.” Med J Aust. 2010; 193(1): 46-52. https://www.mja.com.au/journal/2010/193/1/gastrointestinal-neuroendocrine-carcinoid-tumours-current-diagnosis-and

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