Overview of an Occupational Exposure and an Associated Lung Cancer
The substance called asbestos and the disease called mesothelioma are frequently heard in the same conversation. Even so, this environmental exposure and its resulting conditions are relatively uncommon. When they do occur, the consequences can be a real challenge.
Asbestos
Asbestos is a group of long, thin glass fibres produced for various purposes, including but not limited to home-building materials like pipes and shingles, spray cans, textile materials like rope and tape, and brake linings. Once researchers discovered a clear association between asbestos and lung cancer, specifically bronchogenic carcinoma and malignant mesothelioma, production of asbestos stopped in the latter half of the 20th century, and if work is to be carried out on buildings constructed before the year 2000, a professional Asbestos Refurbishment and Demolition Survey should be conducted before work begins.
The lungs become inflamed by inhaling the fine silicate asbestos fibres and develop permanent damage. Eventually, the person may experience difficulty with breathing (dyspnea), cough, and sometimes chest pain. Asbestos-related lung disease, called asbestosis, often has a long delay from exposure to the onset of symptoms, often after at least 20 years. In addition, individuals exposed to asbestos without concurrent smoking are already six times more likely to develop lung cancer than nonexposed individuals.
Mesothelioma
Mesothelioma is a rare cancer originating from mesothelial cells, which line the pleura surrounding the lungs, the pericardium surrounding the heart, and the peritoneum covering the abdominal organs. Most mesothelioma cases occur in the pleura, with pericardial and peritoneal mesothelioma each seen in less than 10% of cases. Given the timeframe of its natural course, mesothelioma is generally found in older adults.
Mesothelioma classically presents with chest pain and dyspnea. Although these symptoms are not specific to this condition, an occupational history mentioning industries with potential asbestos exposure, including shipyard work, mining, construction work, and manufacturing, raises clinical suspicion for mesothelioma.
Methods to evaluate include thoracentesis to drain a pleural effusion, if present, and imaging studies like x-ray, computed tomography, and magnetic resonance imaging (MRI) of the chest. However, to confirm mesothelioma, a physician must take a biopsy of the tumour and analyse it microscopically by a pathologist.
Options to treat mesothelioma include chemotherapy with cisplatin and other agents, radiation to relieve chest pain, and surgical removal of the affected pleura (pleurectomy) with or without the removal of other lung tissue (pneumonectomy). Unfortunately, mesothelioma is associated with poor survival rates, even with intense treatment using all three modalities. In the best-case scenario, only 14% of patients survive for five years or more.
Possible Medical Breakthrough
Potential breakthroughs may be on the horizon. It has recently been unveiled how asbestos induces cancer. Scientists have now discerned that upon encountering the mesothelium, asbestos provokes the discharge of an enzyme known as TNF-alpha. This enzyme then initiates biochemical alterations within the cells, which prompts the formation of a protein that protects cancer cells from death. As these cancerous cells proliferate, they create more damaged cells, ultimately resulting in cancer.
Based on this newfound knowledge, Biospace has developed a new drug, Onconase, which is currently undergoing clinical trials. The medication functions by impeding the replication of damaged cells, curtailing cancerous growth and reducing tumour size. Encouragingly, the preliminary tests have been quite promising.
The drug is anticipated to help individuals in the advanced stages of mesothelioma to prolong their survival and could even reverse cancer in patients at Stage 1.
With this knowledge, it is hoped that more drugs will be created and tested, ultimately leading to a cure for this debilitating disease.
