From magic mineral to deadly dust
Most people probably don’t know what it looks like or what it is used for, but the word ‘asbestos’ can strike fear into the most sanguine of hearts. Once considered a ‘magic mineral’ due to its fire resistance and general indestructibility, asbestos is now banned in banned in at least 60 countries with other nations moving in the same direction.
So what’s the big problem? The problem is that exposure to asbestos causes mesothelioma, and several other diseases. And although the UK fully banned asbestos in 1999, rates of mesothelioma haven’t declined because the gap between asbestos exposure and disease symptoms can be decades. Mesothelioma is still a rare disease, with around 2,700 diagnoses in the UK each year, but its impact will likely be felt for years to come. The incidence rate in the UK has remained pretty steady in recent years, as has the death rate of around 2,500 each year, but people will still be at risk of developing the disease for years to come because of the presence of existing asbestos in thousands of older buildings, schools, and homes.
Asbestos was a favourite mineral around the world for construction products like roofing and insulation because of its durability, as well as heat and chemical resistance. When asbestos becomes damaged, whether from a construction project or simple ageing, the fibres can become airborne. These fibres are thinner than a human hair and invisible to the naked eye. Once they’re in the air they can easily be inhaled or ingested, which can cause severe damage to the body over time. The fibres can lodge themselves into the linings of the lungs, abdominal cavity, or even heart, but the body is unable to break down these foreign particles. Most commonly, the fibres impact the membrane around the lungs, known as the pleura. This type, called pleural mesothelioma, accounts for about 80% or more of all mesothelioma diagnoses.
After initial exposure, the fibres can cause irritation and scarring, which can eventually lead to tumours. This process can be very slow, perhaps 10-50 years before asbestos victims may begin to see symptoms. Once symptoms finally begin to show, diagnosis is difficult. The symptoms are generally very nonspecific, ranging from shortness of breath to chest pain, so misdiagnosis is very common. These factors often mean patients don’t receive a correct diagnosis until the cancer has progressed to a later stage, with fewer treatment options available. Most patients are expected to live just 12-21 months, though survival rates are improving.
Improvements in survival rates are partially due to advancements in diagnostic methods, and also emerging treatments showing promise in clinical trials. Since mesothelioma is so aggressive, early detection is vital in improving a patient’s prognosis. A number of recent studies have identified biomarkers, specific proteins in the blood, that can help identify mesothelioma cells. One of these studies found the HMGB1 protein could help researchers distinguish between those exposed to asbestos and those who weren’t, as well as identifying mesothelioma versus other diseases. Other biomarkers have also shown similar promise and are still being trialled.
The standard treatment for mesothelioma has been the same for decades, focusing on surgery, chemotherapy and radiation. In recent years, researchers have started testing immunotherapy alongside these more common approaches. Keytruda (pembrolizumab), in particular, has seen promising results in a variety of studies. This immunotherapy drug targets a particular protein to interfere with the growth and spreading of cancerous cells, and has been approved for the treatment of several other cancers including non-small cell lung cancer.
These advancements and ongoing clinical trials give hope to patients facing a rather dire prognosis. The promise of these treatments aids patients today and in the future, providing hope that the field will continue to see improvements in survival rates. Mesothelioma is preventable, but as long as asbestos remains in use around the globe, more lives will be at risk. Education about the disease and its cause are vital for the public’s safety. Until a cure is hopefully found one day, continued research efforts are vital in helping patients beat the statistics and see long-term survival.
To find out more about the work of the Mesothelioma Cancer Alliance visit their website