Japanese pathologists have a new theory that may lead to earlier detection and better outcomes for people with malignant pleural mesothelioma.
Researchers led by the International University of Health and Welfare in Tokyo say exposure to asbestos appears to shorten the telomeres that protect the ends of DNA strands.
The discovery could give doctors another way to diagnose malignant mesothelioma in time to implement more effective treatments.
What are Telomeres?
Telomeres are the caps on the end of each strand of DNA. According to Telomere Activation Sciences, telomeres function like the plastic tips on the ends of shoelaces. Like those tips, telomeres help protect chromosomes from becoming frayed and damaged.
When DNA is damaged, normal cellular processes are disrupted and healthy cells are more likely to become cancerous.
The research team conducted a series of tests on blocks of cells made from pleural effusions (lung fluid) in 35 cases of non-neoplastic lung disease, 12 cases of malignant mesothelioma and 12 cases of lung cancer.
The cell blocks were then analyzed using the fluorescence in situ hybridization method (FISH), a test that looks for genetic changes inside cells.
Mesothelioma Patients Have Shorter Telomeres
When the pleural effusion cells were analyzed, researchers discovered that patients with non-neoplastic lung disease – which can include a range of non-malignant lung problems from interstitial lung disease to asthma – had significantly longer telomeres than patients with malignant mesothelioma or lung cancer.
Fifteen of the patients with non-neoplastic lung disease also had pleural plaques, collagen deposits on the pleural membrane that are common in people who have been exposed to asbestos. In these cases, the telomeres were slightly shorter than those of non-neoplastic patients with no pleural plaques and no (presumed) asbestos exposure.
“These results suggest that telomere shortening and subsequent genetic instability play an important role in the development of malignant mesothelioma,” writes lead investigator Shinsuke Aida.
The report suggests that measuring the length of telomeres in pleural effusion cells “might be helpful for earlier detection of malignant mesothelioma.”
Earlier Detection May Improve Survival
Malignant pleural mesothelioma is a difficult cancer to detect and even harder to treat. Early symptoms of mesothelioma, such as cough, fatigue, and shortness of breath, are often vague and similar to those of other, less dangerous conditions.
Mesothelioma is caused by asbestos exposure, but since the cancer may not develop until decades after exposure, it is not always easy for doctors to make the connection.
A test which could identify the asbestos cancer earlier means that up-and-coming treatments like immunotherapy could be started earlier, potentially improving the odds of mesothelioma survival.
Aida, S, et al, “Measurement of telomere length in cells from pleural effusion: Asbestos exposure causes telomere shortening in pleural mesothelial cells”, August 10, 2018, Pathology International\
“What is a Telomere?”, TA Sciences website