Carcinoid
What are gastrointestinal carcinoid tumours?
Carcinoid is a group of tumours in which cancer cells are found in certain hormone-producing cells. Although they share many features, they seem to have different molecular backgrounds.
According to the site of origin, carcinoid tumours have been divided into foregut (bronchus, stomach, proximal duodenum and pancreas), midgut (distal duodenum to mid-transverse colon), and hindgut (descending colon and rectum) tumours. Since midgut carcinoid is the most common of these tumours and constitute approximately 50% of all carcinoid tumours, this brochure mainly concerns midgut carcinoid. Midgut carcinoid affects 5-7 persons per million population per year. There is no difference in incidence between men and women, and the median age at diagnosis is around 60 years. Midgut carcinoid is normally not hereditary.
What kind of symptoms may midgut carcinoid cause? How is the diagnosis made, and how is the disease treated?
Symptoms
Midgut carcinoid is usually slow-growing and in early stages of the disease there is seldom any clinical symptoms. Eventually the tumour convey metastase to lymph nodes or the liver.
There is a variation in the presentation of the disease and this is often related to the tumourspread.
Some patients go to the doctor because of abdominal pain, caused by the tumourmass, metastases or fibrosis in the mesentery. Another group of patients suffer from hormone related symptoms. Midgut carcinoid produces a variety of endocrine substances, the most frequent of which is serotonin (5-hydroxytryptmine) and tachykinines. These hormones are believed to cause the carcinoid syndrome: diarrhoea, flush, right-sided heart failure and
bronchial constriction. Diarrhoea is typically described as watery stools with a frequency from 2 to 30 per day. Diarrhoea is present in about 80% of the patients. The typical flush is the sudden appearance of a deep red or violet erythema of the upper part of the body, primarily the face and the neck. Flushing attacks may be brief, lasting 2 to 5 minutes or may be prolonged for hours, in some patients the flush becomes permanent.
Flushing attacks occur in about 75% of the patients. Cardiac manifestations involving primarily the right side of the heart is present in about 30% of the patients, and bronchial constriction in approximately 15%.
Diagnosis
If the tumour is surgically removed, the diagnosis is made through analysis of the removed tumour-mass. Otherwise the initial diagnosis is based primarily on the patient´s medical
history, physical examination, and biochemical tumour markers in blood as well as in urine.
To localize the tumour a series of imaging techniques may be employed, computed tomogaraphy (CT), ultrasonogaraphy, magnetic resonance imaging (MRI), somatostatin
receptor scintigraphy (octreoscan) and positron emission tomogaraphy (PET). PET is a relatively new method and is still developing, the method has showed a high rate of lesion
detection even with small midgut carcinoid.
Treatment
The aims of treatment are to reduce hormone levels, control hormonal symptoms, prevent further tumour growth and possibly also achieve tumour reduction. Whenever possible systematic surgical removal of all respectable tumour is performed. Since the majority of patients have metastases at the time of diagnosis surgery is not curative and medical treatment has to be added. The causal medical treatment includes mainly interferon and somatostatin analogues. Interferon is one of the defence mechanisms of the body. Production of interferon is a cellular response to substances such as microbes, tumours and antigens. α-interferon has been showen to be effective in midgut carcinoids, and is taken as subcutaneous injections 3-5 times a week. Somatostatin analogues inhibit the release of various peptide hormones, and have proven to be effective in controlling the symptoms of midgut carcinoid tumours. The drug is taken as subcutaneous or intramuscular injections.
Other treatment options are embolization, radio-frequency ablation and radiotherapy. Embolization means that the hepatic artery is blocked and thereby the tumour cells in the liver deprived of blood supply and die. Radio-frequency ablation comprises heating and
coagulation of tumour cells in the liver, and this leads to cell death. Radiotherapy is a tumourtargeted radioactive treatment, which means that radioactive labelled substances are used.
Research and future outlook
The research at the department is ongoing, to improve existing techniques for diagnosis and treatment as well as developing new techniques and treatment strategies.
New treatment options are tested in clinical trials. A special interests is directed towards new isotopes for use as tumour-targeted radioactive treatment, substances that affect the
angiogenesis in the tumour, and substances that affect receptors at the surface of the tumour cells.
It is important to consider the psychosocial situation for these patients. Research aiming at increasing the knowledge about how patients with midgut carcinoid and their relatives
perceive their situation, and how disease and treatment affect the quality of life of these patients, is in progress.