Malignant mesothelioma is a tumour originating from mesothelial cells. 85 95% of mesotheliomas are caused by asbestos exposure. It occurs much more commonly in the chest (malignant pleural mesothelioma) than in the abdomen (peritoneal mesothelioma). Malignant CAA: March 2015
Malignant Malignant mesothelioma is a tumour originating from mesothelial cells. 85 95% of mesotheliomas are caused by asbestos exposure. It occurs much more commonly in the chest (malignant pleural mesothelioma) than in the abdomen (peritoneal mesothelioma). Rarely mesothelioma arises in the pericardium or tunica vaginalis testis, the membrane surrounding the testicles. Crocidolite (blue asbestos) carries the highest risk, amosite (brown asbestos) is almost as dangerous, and chrysotile (white asbestos) the least dangerous. Some of the cases which arise in patients who cannot recall any asbestos exposure probably result from unidentified occupational or domestic exposure. Many cases have occurred in families of workers exposed to asbestos who carried the dust home on their clothes and hair. Other cases probably arise as a result of contamination of the air by asbestos fibres released from asbestos in the environment. A few cases probably occur spontaneously unrelated to any asbestos exposure. Any type of cancer can arise spontaneously as a result of accidental genetic mutations The malignant mesothelioma is indicated by yellow arrows, the central pleural effusion is marked with a yellow star. (1) right lung, (2) spine, (3) left lung, (4) ribs, (5) aorta, (6) spleen, (7) left kidney, (8) right kidney, (9) liver. It is accepted by all expert bodies, including the World Health Organisation, that all types of asbestos cause mesothelioma. In the UK, there are more than 2000 deaths from mesothelioma each year. Mortality is beginning to decline in younger men but overall is expected to increase by 10-20% over the next 5-10 years, then to fall gradually. may occur after a small exposure to asbestos but the risk increases with the amount of asbestos exposure. The Number: SCO17874 Registered Office: 245 High Street, Glasgow, G4 0QR. Tel 0141 552 8852. Page 1
usual interval between first exposure to asbestos and death from mesothelioma is around 40 (30-50) years but may be as little as 10 years or as much as 60 years or more. The risk of mesothelioma is not affected by smoking. Presentation and Diagnosis Patients with pleural mesothelioma usually present to their doctor with chest pain and/or breathlessness. Usually there is a pleural effusion (i.e. fluid in the chest cavity) accounting for the breathlessness. They may have a cough, feel tired and generally unwell. Chest X-rays and CT scans often lead to a strong suspicion of mesothelioma. It is necessary to take samples of tissue (a biopsy) from the tumour or fluid from the pleural cavity for examination under the microscope in order to confirm the diagnosis. The samples can often be obtained by passing a special needle through the skin of the chest. This is often done with help from an ultrasound scan or CT scan to make sure the most appropriate area is sampled. These procedures are done under local anaesthesia. Sometimes these methods do not give the diagnosis. It is then necessary to perform a small operation known as a thoracoscopy or pleuroscopy. This is done under general anaesthesia or sometimes under local anaesthesia. It involves small incisions in the chest between the ribs to allow a viewing telescope and forceps to be passed into the chest. The surgeon can see the tumour and take samples from it. When the samples have been obtained the pathologist looks at them under the microscope and performs special stains to identify the tumour as a mesothelioma and to determine the type of mesothelioma. This often takes a week or more. The principal histological varieties are epithelioid, sarcomatoid and mixed. Patients with the epithelioid type tend to survive a little longer. The median survival from presentation is 12 18 months; a few patients with epithelioid tumours survive for more than 5 years. It is important to Number: SCO17874 Registered Office: 245 High Street, Glasgow, G4 0QR. Tel 0141 552 8852. Page 2
appreciate that these are average figures and should not be taken as predictions of life expectancy for an individual patient without consideration of the particular circumstances of that patient. Treatment of The standard treatment for mesothelioma is often referred to as best supportive care (BSC) or active symptom control (ASC), to highlight the fact that the doctors and nurses will be seeking actively to identify and relieve symptoms of the disease. Increasingly chemotherapy is regarded as part of standard treatment for patients fit enough to receive it. In the earlier stages of pleural mesothelioma there is often a recurrent pleural effusion which causes breathlessness. This is dealt with by pleurodesis which means inducing adhesions between the lung and chest wall. This closes off the pleural space so the effusion cannot reform. It is usually performed by putting sterile talc into the chest through the tube used to drain the fluid. Chest pain is another common problem. Painkilling drugs are usually effective. If pain remains severe despite drugs a minor surgical procedure called cordotomy can be effective. This is done under local anaesthesia and the aim is to disable the pain carrying nerves in the spinal cord. Various other symptoms including sweating, loss of appetite and weight may also be helped by medication. Surgery for In some cases it is helpful to remove the pleura from around the lung to help the lung to expand better, a procedure known as pleurectomy (sometimes referred to as decortication). This procedure cannot eliminate the mesothelioma completely and it grows back again. In highly selected cases with early stage disease more radical surgery called extra-pleural pneumonectomy can be considered. The surgeon attempts to remove the mesothelioma completely, which involves taking out the whole lung and parts of neighbouring Number: SCO17874 Registered Office: 245 High Street, Glasgow, G4 0QR. Tel 0141 552 8852. Page 3
structures i.e. the diaphragm which separates the lung from the abdomen and the pericardium, the covering of the heart. Some experienced clinicians report that a few patients enjoy long term survival after this procedure. However, the average survival is no better for patients subjected to radical surgery than for patients treated with chemotherapy. Radiotherapy for Some doctors recommend radiotherapy to the chest wall at the sites of chest drain insertion or a biopsy in order to prevent the mesothelioma growing through the skin. There is some uncertainty as to the effectiveness of this treatment and some doctors do not believe it is worthwhile. There are two main uses of radiotherapy to treat symptoms. One is to treat a chest wall tumour which is forming a lump beneath the skin and which is causing discomfort or pain. Radiotherapy can shrink the lump and alleviate pain. The other is to relieve deeper seated pain which is not responding well to pain relieving drug therapy. Chemotherapy for Chemotherapy can prolong survival in patients with mesothelioma. The average gain is around 2 to 3 months. This may not sound very much but the average represents some patients whose mesotheliomas do not respond to therapy who may not live any longer than they would have done without chemotherapy and others whose mesotheliomas respond well and whose survival gain is more than the average of three months. As yet there is no way to predict before treatment starts which mesotheliomas will respond well and which will not. The chemotherapy of first choice is pemetrexed (trade name Alimta) in combination with either cisplatin or carboplatin. The drugs are given through a drip in an arm vein. The treatment is given on an out-patient basis and does not require hospitalization. Usually 4 to 6 cycles are administered at 3 week intervals. A CT scan is performed after every 2 or 3 cycles to assess Number: SCO17874 Registered Office: 245 High Street, Glasgow, G4 0QR. Tel 0141 552 8852. Page 4
progress. If the mesothelioma has stayed the same size or shrunk treatment is continued but if the tumour has grown treatment is discontinued. The treatment is generally well tolerated and can help symptoms of the illness as well as prolong survival. However, some patients do not tolerate it well in which case it is discontinued. Side effects are usually not severe but can include sore mouth and eyes, tiredness and sickness. There is usually little, if any, hair loss. Another type of chemotherapy used is vinorelbine (trade name Navelbine). This can also relieve symptoms of mesothelioma and it can probably prolong life by an average of 2 months, although the evidence for prolongation of life is less strong than for pemetrexed. This drug has the advantage of being available in tablet form so the treatment can be given without the need for hospital admission. It is usually well tolerated without serious side effects. Vinorelbine can be used as second line therapy in patients who have previously received pemetrexed. Source: Dr. Robin Rudd, MA MD FRCP Consultant Oncologist St. Bartholomew s Hospital London www.clydesideactiononasbestos.org.uk/asbestosrelated-disease/mesothelioma CAA. 2015. All rights reserved. Number: SCO17874 Registered Office: 245 High Street, Glasgow, G4 0QR. Tel 0141 552 8852. Page 5