‘Better’ test for asbestos cancer

Scientists claim they have developed a more sensitive test for the asbestos-related cancer mesothelioma.

The cancer develops long after exposure to asbestos but patients usually have a limited life expectancy.

The test developed by a team at Oxford University looks at levels of a protein closely linked to the cancer in fluid around the lungs.

A UK lung expert welcomed the American Journal of Respiratory and Critical Care Medicine study.

Mesothelioma is an invariably fatal tumour found in the surface of the lung. While relatively rare, it is very difficult to treat because of its location and because it does not seem to respond well to chemotherapy.

The disease has been found in people with no history of exposure to asbestos, but inhaling the dust released by the mineral when it is broken up is known to be a key risk factor.

It has particularly affected tradesmen such as joiners, plumbers and electricians.

Because it can take many decades for the disease to develop, experts expect the number of cases in the UK to peak at around 2,200 by 2013.

Laws preventing occupational exposure to asbestos are in place in the developed world. There are no such restrictions in developing countries, however.

High levels

The researchers focused on ways of distinguishing mesothelioma as a cause of pleural effusion, the build-up of fluid in the pleural cavity surrounding the lungs.

There are many causes of this symptom, many of which are benign or linked to other types of cancer but over 90% of people with mesothelioma have the symptom.

At the moment, doctors carry out pleural fluid cytology – a lab test which looks for cancerous cells.

However the Oxford team say this is not a very sensitive test.

Team members used pleural fluid samples from over 200 patients who had been referred to a specialist respiratory clinic.

They then looked at levels of the protein meothelin – which is released in high quantities in the pleural fluid of most patients with mesothelioma.

It was found that levels of the protein were almost six times higher in patients with the cancer than in those with secondary lung cancers, and 10 times greater than those with benign conditions.

Rapid diagnosis

Dr Helen Davies, who worked on the research, said: “This study suggests a way for clinicians to more readily identify cases of mesothelioma from the start.”

She added: “Because mesothelioma has a median survival time of 12 months, minimising the number of invasive procedures and tests patients require is crucial to reduce morbidity and the time they need to spend in hospital.

“An earlier diagnosis also allows speedier interventions to relieve symptoms as well as initiation of other treatments such as chemotherapy or radiotherapy if appropriate.

“Claims for worker’s compensation may also be instigated once the diagnosis is confirmed.”

Dr Paul Beckett of the British Thoracic Society said: “A simple test which can exclude the diagnosis without resort to more invasive methods would be welcomed, allowing a more streamlined diagnostic pathway both for those with and without the disease.

“Such a pathway would be expected to lead to more rapid diagnosis and therefore treatment and perhaps improve the outlook for this disease, as well as avoiding unnecessary tests in those who don’t have mesothelioma.”  –BBC News