What are carcinoid tumours?
Carcinoid tumours constitute a group of tumours originating from neuroendocrine hormoneproducing 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 midtransverse colon), and hindgut (descending colon and rectum) tumours. Bronchial carcinoid tumours constitute 20-25% of all carcinoid tumours, this brochure mainly concerns bronchial carcinoid. Bronchial carcinoid affects 2 persons per million population per year. The disease is slightly more common in females than in males, and the median age at diagnosis is around 50 years but all ages can be affected. Bronchial carcinoid is normally not hereditary, however, sometimes it is a part of the hereditary syndrome MEN I (multiple endocrine neoplasia type I).
What kind of symptoms may bronchial carcinoid cause? How is the diagnosis made, and how is the disease treated?
Symptoms
Bronchial carcinoid tumours are usually slow-growing and in early stages of the disease there is seldom any clinical symptom. In about 20% of the patients the tumour convey metastases to lymph nodes, liver or bone. There is a variation in the presentation of the disease. Many of the patients present with long-standing cough, however, in some patients the tumour is diagnosed incidentally on routine chest radiography. Other presenting symptoms include recurrent pulmonary infections, haemoptysis, wheezing, dyspnoea and chest pain. Some patients suffer from hormone related symptoms. Bronchial carcinoid tumours produces a variety of hormones, of which some cause symptoms and some do not. Some tumours produces histamine and this may cause the atypical carcinoid syndrome with light red flushing, swelling in the face and increased tear and saliva secretion. One other hormone that can be produced by the tumour is serotonin (5-hydroxytryptmine). This hormone are believed to cause the classical carcinoid syndrome: diarrhoea, flush, right-sided heart failure and bronchial constriction. Ectopic Cushing´s syndrome, resulting from secretion of ACTH occurs in some patients. It has typical symptomatology, including hypertension, trunk obesity, moonshaped face and gain of weight.
Diagnosis
When the tumour is surgically removed, the diagnosis is made through histopathological analysis of the removed tumour-mass. If surgery can not be performed a needle biopsy is usually obtained for pathological examination. The initial diagnosis is also 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 undergoing development. The method has shown a high sensitivity in detecting lesions even in small bronchial carcinoids.
Treatment
The aims of treatment are to reduce hormone levels, control hormone induced symptoms, prevent further tumour growth and possibly also achieve tumour reduction. Whenever possible systematic surgical removal of all resectable tumour is performed. If the operation is not radical or the patient has metastases at the time of diagnosis surgery is not curative and medical treatment has to be added. The causal medical treatment includes mainly chemotherapy, interferon, or somatostatin analogues. Chemotheraputic drugs are cytotoxic agents that have a checking or stopping effect on cell division. Chemotherapy has effect on all cells in the body but mostly on those that are rapidly growing, such as cancer cells. There is a lot of different kinds of chemotherapeutic agents that are used alone or in combinations. Chemotherapy treatment is always given at the hospital.. Interferon is one part of the immune system in the body. Interferons are produced by white blood cells as a response against viral infections. α-interferon has showed to be effective in midgut carcinoid, 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 carcinoid tumours. The drug is taken as subcutaneous or intramuscularly injections.
Other treatment options are embolization and radiotherapy. During embolization arterial blood supply to one of the liver lobs is blocked and thereby the tumour cells in the liver become depraved of blood supply and die. External radiotherapy is used for palliation of bone metastases but may also be considered as adjuvant treatment postoperatively against the area of the primary bronchial tumour. Radiotherapy can also be used as a tumour-targeted radioactive treatment, which means that radioactive labelled substances is 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 bronchial carcinoid and their relatives perceive their situation, and how disease and treatment affect the quality of life of these patients, is in progress.