A new study of pleural mesothelioma in Nordic countries highlights the critical role of asbestos in mesothelioma development.
Asbestos is the primary cause of mesothelioma around the world. There are many statistics on the incidence of mesothelioma in countries that use asbestos. But there is not much information on mesothelioma incidence, mortality, and survival prior to the popularity of asbestos. This makes it difficult to quantify the influence of asbestos in mesothelioma development.
Researchers from the Czech Republic, Germany, Finland and China compiled the new information using the NORDCAN cancer database. The database includes statistics on mesothelioma in Denmark, Finland, Norway, and Sweden dating back as far as the 1940s.
Their analysis, published in BMC Cancer, is a sobering reminder of the deadly legacy of asbestos. But it also contains some hopeful news that limiting asbestos exposure can reduce mesothelioma deaths.
Mesothelioma Mystery Solved
As early as the 1930s and 40s, some workers started to get sick with a deadly lung disease. It was a disease doctors had never seen before. Many of the sick workers worked around asbestos in mines or factories. But it was many years before scientists made the connection to asbestos in mesothelioma development.
Asbestos is a naturally-occurring mineral that is plentiful, inexpensive, and strong. These qualities made it a popular component in insulation, construction products, and all kinds of fire-proofing materials. Thousands of homes, buildings, and ships were filled with asbestos-containing products.
By the time the link between the mineral and the cancer was clear, many companies were already using asbestos heavily. Some of these companies went to great lengths to try to cover up the role of asbestos in mesothelioma development among their workers.
Even today, some negligent companies still deny that they failed to protect or warn their employees about the risk of asbestos exposure.
Studying Asbestos in Mesothelioma Development
The lowest incidence of mesothelioma in Nordic countries was among Norwegian women and Finnish men in the mid-1950s. At that time, mesothelioma occurred in 0.02 out of 100,000 women in Norway. Among men in Finland, the rate of mesothelioma was 0.05 in 100,000. The researchers note that these rates were “before the influence of asbestos”.
Forty years later, the influence of asbestos in mesothelioma development was apparent. The highest rate of pleural mesothelioma occurred in Denmark in 1997 when 1.9 out of 100,000 people developed mesothelioma.
“The regional incidence trends matched with earlier asbestos-related industrial activity, shipbuilding in Finland and Sweden, cement manufacturing and shipbuilding in Denmark and seafaring in Norway,” reports Kari Hemminki of Charles University in Prague.
About 30 percent more mesothelioma patients now survive for a year in these countries. The five-year survival rate has not changed. Fewer than 10 percent of people diagnosed with mesothelioma in a Nordic country live for at least five years.
But there is an up-side to the role of asbestos in mesothelioma development: When asbestos exposure is reduced, mesothelioma rates go down. The study bore this out. All the Nordic countries banned asbestos in the 1980s. Their rates of mesothelioma are now declining.
Hemminki, K, et al, “Incidence, mortality and survival in malignant pleural mesothelioma before and after asbestos in Denmark, Finland, Norway and Sweden”, November 8, 2021, BMC Cancer, Open access online report, https://bmccancer.biomedcentral.com/articles/10.1186/s12885-021-08913-2