Mesothelioma cancer accounts for less than 1 per cent of all cancers diagnosed in the UK and consequently, has previously been mistakenly diagnosed as a lung cancer condition. A further problem can also arise because cancer of the lung tissue itself is also known to be caused by asbestos exposure.
The correct diagnosis of any asbestos-related disease can present a challenge as symptoms develop gradually, are non-specific, and closely resemble other conditions or diseases. Nevertheless, it is crucial to the outcome of a claim for mesothelioma compensation, which is determined by establishing a causal connection between asbestos exposure and the subsequent onset of asbestos-related disease.
Different body tissues
While there is no doubt that exposure to and inhalation of asbestos fibres is the sole cause of malignant mesothelioma cancer, it is because the symptoms are very similar to lung cancer that attributing causal connection can become confused, even though the two conditions occur in different tissues of the body.
Whereas, lung cancer affects the lung tissue itself, mesothelioma cancer attacks the pleura – the thin membrane which lines the inside of the chest cavity and covers both the lungs and other organs.
At a later stage, mesothelioma may also spread to the lung tissue, but always begins in the linings of the chest cavity. Although pleural mesothelioma is the most common form of the cancer, it can also attack the surrounding, protective lining of the stomach ( peritoneal) or heart (pericardial).
Another significant challenge has been the unusually long gestation period of up to 50 years or more between the initial period of exposure when asbestos fibres were first inhaled and the eventual appearance of asbestosis symptoms.
Patients can often confuse the first signs of illness, such as shortness of breath, a chronic cough or chest pain with a number of other common types of respiratory disease, such as flu or bronchitis.
A painstaking process of elimination will be required even when it is known that asbestos exposure originally occurred or the patient has a history of asbestosis, which can lead to the development of asbestos cancer in around 1 out of 7 cases.
Investigations and examinations
The investigation begins with taking a thorough and accurate medical history of the patient, work history, and family medical history, plus any cultural and environmental factors. This is followed by a general examination and possible laboratory tests.
Where a lung condition is suspected, a pulmonary function test is taken for lungs and breathing and a chest x-ray to detect for lung abnormalities, including pleural thickening (scarring) and effusions (excessive liquid). Once the presence of any lung abnormalities is established, further tests may be required to determine the presence of asbestos lung cancer, how far it has progressed, and any possible asbestosis treatments.
Asbestos lung cancer cannot be diagnosed without the information provided by a biopsy, which collects fluid samples and analysis of the tissue affected to conclusively determine if cancer is present, how far it has progressed, and to decide treatment options.
Although patients diagnosed with lung cancer may have large or multiple tumours, they tend to be individually, concentrated masses with clearly defined boundaries in contract to mesothelioma, which is characterised by diffuse malignancies and the “tumour” not contained in a single mass but spread across the surface of the chest linings.
Treatments and life expectancy
For the same reason, lung cancer is more receptive to chemotherapy and radiation, whereas both of these therapies are usually unable to inhibit the growth of the diffuse malignant tissues in mesothelioma.
The treatment and life expectancy for those diagnosed with lung cancer has significantly improved in recent years, and depending on the stage the disease has reached, between 15 and 75 per cent of lung cancer patients can expect to live for a further five years or more. However, fewer than 10 per cent of patients diagnosed with the still incurable mesothelioma cancer are able to live two years or longer past diagnosis.
According to latest available figures published by the Health and Safety Executive, in 2010 the number of mesothelioma fatalities recorded in the UK on the mesothelioma register was 2,347 while the estimated number of asbestos related lung cancer deaths was 2,000.