CUHK
News Centre

Mesothelioma has a very poor survival rate compared to other cancers: only 8% over five years on average. Medical researchers are always seeking new treatments and knowledge of this disease. The Chinese University of Hong Kong (CUHK)’s Faculty of Medicine (CU Medicine) has conducted a study with the Association of Pacific Rim Universities (APRU) to investigate the global distribution, risk factors and epidemiological trends of mesothelioma. The results showed that the incidence of mesothelioma was higher in high-income jurisdictions and was closely related to per capita gross domestic product (GDP), human development index (HDI) and the prevalence of occupational exposure to asbestos at the country level.

The global incidence of mesothelioma has shown an overall declining trend in recent years due to restrictions on asbestos use. However, an increasing trend was observed in females in some countries. The researchers recommended that risk factor control and early cancer detection should be implemented among high-risk populations. Details of the study were published recently in the renowned international medical journal Journal of Thoracic Oncology.

Mesothelioma is related to asbestos exposure, with a higher incidence in high-income countries

Mesothelioma is a rare cancer that starts in the thin layer of tissue (mesothelial cells) covering the surface of internal organs. About three-quarters of mesothelioma first appears in the chest, where it is known as pleural mesothelioma. Most patients develop the disease at between 40 and 70 years old, and it is more frequently found in males than females. The formation of malignant pleural mesothelioma is strongly associated with exposure to asbestos in specific occupations, in the general environment or through contact with construction materials. Common symptoms include coughing, tiredness, weight loss, difficulty breathing, abdominal swelling and chest wall pain due to fluid retention in the lungs.

According to the Hospital Authority of Hong Kong, there were 455 new cases of and 349 deaths from mesothelioma over the past two decades (2001-20). In 2008, the Hong Kong government amended the Pneumoconiosis and Mesothelioma (Compensation) Ordinance to provide mesothelioma patients with the same level of compensation as those suffering from pneumoconiosis. Although the import, transhipment, supply and use of all types of asbestos and asbestos-containing materials are currently forbidden, asbestos residues and exposure risks may still exist in some buildings over 30 years old in Hong Kong.

To understand the most updated geographical distribution and identify population groups at high risk of mesothelioma, the research team retrieved data from international databases such as the Global Cancer Observatory, International Cancer Incidence Database and WHO Global Health Observatory Data Repository for the age-adjusted incidence and prevalence of different risk factors. The researchers found that the disease burden of mesothelioma varied across regions, with Northern Europe having the highest incidence (see details in Table 1). In addition, the disease burden of mesothelioma was proportional to GDP, HDI and the prevalence of occupational asbestos exposure. This implies that a country or region with a higher level of those risk factors will have increased morbidity from mesothelioma.

Global mesothelioma incidence is declining, yet the rate in females is on the rise

Mesothelioma incidence has been declining globally over the past decade, yet an increasing trend was found in females in some economies. Using the “Average Annual Percentage Change (AAPC¹)” for comparison, the largest increase in incidence rate among females was found in Thailand, followed by Bulgaria and South Korea (see details in Table 2).

Dr Jason Huang Junjie, the first author of the study and Research Assistant Professor from The Jockey Club School of Public Health and Primary Care at CU Medicine, said, “The incidence of mesothelioma varies by region, which may be related to detection and diagnosis ability, environmental and lifestyle risk factors, and policies restricting asbestos use. Our study provides the most up-to-date evidence on the global distribution, risk factors and trends of mesothelioma. Policymakers should implement evidence-based, targeted prevention strategies to control relevant risk factors, especially exposure to asbestos.”

Professor Martin Wong Chi-sang, the senior corresponding author of the study, from The Jockey Club School of Public Health and Primary Care at CU Medicine, added, “The overall incidence of mesothelioma has been declining in recent years, but it is alarming that it is increasing among females in some regions. The causes of this trend remain unknown and could be related to non-occupational exposure to asbestos, such as in the general environment. Future studies should explore the reasons behind these epidemiological transitions, so that they can provide insights into the cause and prognosis.”

Study details can be found at: https://doi.org/10.1016/j.jtho.2023.01.095

¹ AAPC is a measure of the overall changes in cancer incidence during a specific period. For example, if the incidence AAPC of a certain cancer in a country is five for the past 10 years, it means that the incidence in that country increased 5% on average each year over the 10-year period.