Mesothelioma is a cancer affecting the mesothelial cells which cover most internal organs. There are two main types of mesothelioma; pleural and peritoneal.
This is a type of cancer that starts in the membrane that covers the lungs. Although it develops in the chest and involves the lining of the lungs, it is not a lung cancer and it is treated differently to lung cancer.
Pleural mesothelioma is the most common type of mesothelioma, and accounts for about 90% of all mesotheliomas.
Symptoms of pleural mesothelioma
The main symptoms of pleural mesothelioma include:
- shortness of breath – which usually worsens with activity or when lying down
- chest pain or pain in the shoulder and upper arm
- loss of appetite, weight loss
- persistent cough or a change in a person’s usual cough
- heavy sweating, particularly at night.
Early signs of pleural mesothelioma are similar to other conditions and diseases, however, if you think you have been exposed to asbestos, talk to your doctor.
The other main type is peritoneal mesothelioma, accounting for about 10% of cases. It develops in the lining of the abdomen.
Symptoms of peritoneal mesothelioma
The main symptoms of peritoneal mesothelioma include:
- swollen or painful abdomen
- loss of appetite
- bowel or urinary problems.
Less commonly, mesothelioma begins in the membrane around the heart or the reproductive organs. Growths form which gradually grow and spread to surrounding areas. Rarely, a person may develop mesothelioma in more than one place.
Causes of mesothelioma
The only known cause of mesothelioma is exposure to asbestos. It can take many years after being exposed to asbestos for mesothelioma to develop.
Sometimes mesothelioma is linked to previous radiotherapy to the chest.
Screening for mesothelioma
There is currently no screening for mesothelioma available.
Diagnosis for mesothelioma
If you or your doctor suspects you may have mesothelioma you may have some of the following tests:
Blood tests can check your overall health and how your blood cells, liver and kidneys are working.
X-rays can help identify any abnormalities in the lungs, thickening of the pleura or fluid in the space between the lungs and the chest wall. X-rays will also help identify fluid in the abdomen.
CT scans produce three-dimensional pictures of several organs at the same time and can also scan chest lymph nodes. CT scans may also be used to see if the mesothelioma has spread to other locations.
A biopsy is when a sample of pleural or abdominal tissue is removed for examination under a microscope. It is the main procedure used to diagnose pleural mesothelioma, and can be taken in two ways: via VATS (Video-assisted thoracoscopic surgery), a type of keyhole surgery; or via CT-guided core biopsy, which is done under a local anaesthetic using a needle guided by a CT scan.
Draining fluid from the pleura
This can be done to relieve symptoms of breathlessness caused by pleura leaking into the pleural cavity (called pleural effusion), and in some instances, to diagnose pleural mesothelioma. People with peritoneal mesothelioma may have fluid in the abdomen (called peritoneal effusion), causing swelling and pain.
Using an ultrasound scan to guide the doctor, the fluid is drained via a needle inserted through the chest wall into the pleural cavity or into the abdomen. A sample of the fluid is then sent to a pathologist for testing.
Mesothelioma can be difficult to diagnose as the cells can look similar to other types of cancer cells. Combining results from fluid samples with information from an x-ray and CT scan can provide an acceptable level of certainty of a diagnosis.
If mesothelioma is diagnosed, further tests are usually done to find out if the disease has spread to other parts of the body, such as CT scans; FDG-positron emission tomorgraphy (FDG-PET); mediastinoscopy (used to examine and sample lymph nodes at the centre of the chest); or endobronchial ultrasound (EBUS).
Treatment for mesothelioma
Although there is currently no cure for mesothelioma, active treatment is recommended for some people. This can include chemotherapy, radiotherapy or surgery, or a combination of these treatments. It can help some people to achieve a longer period of control over the disease.
Chemotherapy drugs aim to destroy cancer cells while causing the least possible damage to healthy cells. The most commonly used chemotherapy drugs for treating pleural mesothelioma include pemetrexed with cisplatin or carboplatin.
Chemotherapy is given directly into the abdomen for people with peritoneal mesothelioma.
Radiotherapy, the use of x-rays to kill or damage cancer cells, can be used at different stages of pleural mesothelioma and in different ways. For example, it can relieve symptoms such as pain caused by tumours, and it can be given after chemotherapy or surgery, to help kill remaining cancer cells. Radiotherapy is rarely used to treat peritoneal mesothelioma.
There are two main types of operations considered for actively treating pleural mesothelioma: extrapleural pneumonectomy (PPE), which removes the tumour and the pleura, the affected lung, the diaphragm and a portion of the lining of the heart; or a pleurectomy with pulmonary decortication (P/D), which removes the pleura and as much disease as possible.
In contrast, surgery is generally not an option for peritoneal mesothelioma. When it is an option, the lining of the abdomen is removed in a procedure called a peritonectomy.
When mesothelioma is diagnosed at an advanced stage, the main goal of treatment is to manage the symptoms and keep them under control as long as possible.
Treatments can include surgery to improve breathlessness caused by fluid build-up. VATS (video-assisted thoracoscopic surgery) and involves removing some of the lining of the chest wall and lung. During the procedure, sterile talcum powder is injected into the pleural cavity, causing inflammation that closes the pleural cavity and helps prevent fluid from building up again.
More extensive open surgery can also be undertaken to drain fluid build-up in the lungs, or to relieve pain in the chest. For people not suitable for VATS or open surgery, an indwelling pleural drain may be used, which allows fluid to be drained 1-2 times a week, depending on how quickly the fluid builds up again.
The treatment team will discuss with the person, suitable treatment options to assist with other symptoms such as sleeplessness, pain, fatigue, loss of appetite and weight loss.
Although it is most often used by people with advanced cancer, palliative treatment can be used at any stage of cancer treatment. It is intended to improve a person’s quality of life by alleviating the symptoms of cancer, without trying to cure the disease.
Treatment may include radiotherapy, chemotherapy and other medicines. It can include pain relief, and the management of other physical and emotional symptoms.
If you are diagnosed with mesothelioma you will be cared for by a range of health professionals, which may include:
- radiologist, who specialises in reading chest x-rays, CT scans and other scans
- respiratory physician, who investigates symptoms, is involved in diagnosis and determines initial treatment options
- interventional radiologist, who uses CT scans to guide needles and other instruments for draining fluid and removing tissue for diagnosis
- pathologist, who examines cells and tissues under a microscope
- thoracic surgeon, who conducts some biopsy procedures, and performs surgery
- medical oncologist, who prescribes and coordinates chemotherapy treatment
- radiation oncologist, who prescribes and coordinates the course of radiotherapy
- palliative care team, who assist with control of symptoms as well as offering a range of support services
- nurses, who support you through all stages of your treatment
- other allied health professionals, including dietitian, physiotherapist, social worker and occupational therapist.
Prognosis for mesothelioma
It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person’s individual circumstances. However, your doctor may give you a prognosis, the likely outcome of the disease, based on the type of mesothelioma you have, the test results, the rate of tumour growth, as well as your age, fitness and medical history.
In general, the earlier cancer is diagnosed, the better the outcome. However, mesothelioma is often diagnosed once it has advanced, as often the early symptoms can go unnoticed. Although it is more difficult to treat advanced cancer successfully, it may be possible to keep the disease under control for months or years, and quality of life can be improved by relieving the symptoms.
Reducing your exposure to asbestos is the most likely way to lower your risk of mesothelioma, whether at work or in the home.