CARCINOID SYNDROME

OVERVIEW

Carcinoid syndrome is the constellation of systemic signs and symptoms associated with malignant neoplasms of enterochromaffin cells. Cutaneous flushing, diarrhea, and cardiac valvular lesions are the most common endocrine consequences of these tumors.

Carcinoid tumors can occur almost anywhere in the gastrointestinal tract but primarily in the stomach, small intestine, appendix, colon, and rectum.

Carcinoid tumors have a proclivity to metastasize to the liver and may involve this organ extensively and predominantly.

Extrahepatic metastases occur in bone, where they are often osteoblastic, and in the lung, pancreas, spleen, ovaries, adrenals, and other organs.

The carcinoid syndrome may include manifestations such as abdominal pain, wheezing, facial flushing, diarrhea, heart disease, and "carcinoid crisis."

CLINICAL MANIFESTATIONS

Symptoms will depend on where in the body the tumour develops.

A lung carcinoid tumour may cause:

• a cough which may make you cough up blood
• wheezing
• breathlessness
• chest pain
• tiredness

A stomach carcinoid tumour may cause:

• pain
• weight loss
• tiredness and feeling weak

A bowel carcinoid tumour may cause:

• belly pain
• a blocked bowel (diarrhoea, constipation, feeling or being sick)
• bleeding from the bottom

An appendix carcinoid tumour doesn't tend to cause any symptoms; it's usually only discovered when the appendix is being removed for another reason. 

Symptoms caused by the hormones (carcinoid syndrome)

Typical symptoms of carcinoid syndrome are:

• diarrhea, belly pain and loss of appetite
• flushing of the skin
• fast heart rate
• shortness of breath and wheezing

These symptoms may come on unexpectedly as the hormones can be produced by the tumour at any time

CAUSES

It is not currently understood why carcinoid tumours develop, but it's thought that most cases happen by chance.

However, some cases may run in families. According to Cancer Research UK, carcinoid tumours are likely to be more common in:

• people with a rare family syndrome called multiple endocrine neoplasia type 1 (MEN1)
• children of parents with a carcinoid tumour, or those with an affected sibling
• children of parents with squamous cell skin cancer, non-Hodgkin's lymphoma, or cancer of the brain, breast, liver, womb, bladder or kidney
• people with a condition called neurofibromatosis
• overproduction of serotonin and tachykinins

DIAGNOSIS

When all of its clinical features are present, carcinoid syndrome is easily recognized. The diagnosis also must be considered when any one of its clinical manifestations is present.

·         The diagnostic hallmark consists of overproduction of 5-hydroxyindoles accompanied by increased excretion of urinary 5-HIAA Normally, excretion of 5-HIAA does not exceed 9 mg daily. Ingestion of foods containing serotonin (ie bananas and walnuts)  may complicate the biochemical diagnosis of carcinoid syndrome

·         Plasma chromogranin A levels may be elevated by neuroendocrine tumors, including carcinoids, and may serve as a marker of tumor mass, such as during cytoreductive therapy. The diagnosis value of plasma chromogranin A, however, is relatively low. Assessment of the extent and localization of both primary and metastatic tumor is aided by computed tomographic scans of the abdomen and chest and by imaging with radionuclide-labeled somatostatin receptor ligands.

·         Carrying out a series of scans and tests endoscopy helps to determine this condition

TREATMENT

Treatment of the carcinoid syndrome is directed toward pharmacologic therapy for humorally mediated symptoms and the reduction of tumor mass.

·         Somatostatin can prevent the flushing and other endocrine manifestations of the carcinoid syndrome through reduction in urinary 5-HIAA excretion and in tachykinin levels in blood. Octreotide is analogues of somatostatin , with longer biologic half-lives than the native hormone, has made subcutaneous administration a feasible route of therapy

·         iotherapy to kill some of the cancer cells, Cancer Research UK has more information on targeted radiotherapy and external beam radiotherapy, the two options

·         a procedure to block the blood supply to the carcinoid tumour (only for tumours in the liver), known as hepatic artery embolisation

·         a procedure that uses a heated probe to kill cancer cells (only for tumours in the liver), called radiofrequency ablation

·         Surgical removal of non-metastasized tumor

REFERENCES

WB Saunders

http://www.nhs.uk/conditions/carcinoid-syndrome/Pages/Introduction.aspx

 http://www.medicinenet.com/carcinoid_syndrome/article.htm

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