Worldwide, mesothelioma is usually found to be caused by past occupational exposure to asbestos. Family members too are vulnerable because of indirect exposure to asbestos through clothing of the occupationally exposed. In an overwhelming majority of cases, mesothelioma affects men and the Netherlands is no exception.
Mesothelioma is a cancer of protective tissues over the lungs (in which case the condition is termed ‘pleural mesothelioma’). A fewer cases affect the tissues covering the heart (‘pericardial mesothelioma’) and the gastro-intestinal tract (‘peritoneal mesothelioma’).
All types of mesothelioma are almost always malignant. The mean latency period of this cancer as seen in the Netherlands is 40 years, lower than the upper limit of 50-60 years seen in other countries. As a result, most cases of mesothelioma anywhere in the world are aggravated beyond cure by the time it is detected. Time between diagnosis and death varies from less-than-a-year to two years. The Netherlands however is in the forefront of medical research in coordination with other countries, notably Australia and the United States.
Epidemiology of mesothelioma in the Netherlands
A study of asbestos-related diseases mesothelioma in the Netherlands is hamstrung by the following factors:
- A mesothelioma register did not exist in the country until recently.
- Asbestos-related diseases have traditionally been underreported even in the Dutch national register for occupational diseases.
- Hospital record and death certificates provide little or no data about occupational background.
- Some authoritative studies have used rather unconventional sources of information, such as lawyers’ records.
In view of the above, only a few cases of mesothelioma officially came to light until 2000. Despite the limited availability of official data pertaining to the previous century, it is possible to make certain significant inferences from more recent studies. The inferences are:
- The mean latency period is 40 years (nine years less than in Italy).
- The mean age at death is 62.9 years. This is four years lower than in Australia and slightly higher than in Germany.
- The mean age at death is significantly lower in cases of mesothelioma caused by household or environmental exposure to asbestos as compared to occupational exposure. As an extreme case was the death of a 34-year-old son of an asbestos cement worker.
The population segments most vulnerable to mesothelioma in the Netherlands are people who have worked in the following sectors:
- Shipbuilding
- Construction and maintenance
- Insulation
- Navy and army
- Coal mining
- Asbestos-cement
- Metal production
A significant feature of mesothelioma in the Netherlands is that patients who contracted the disease from non-occupational exposure to asbestos have had lower survival period than those who got the disease from occupational exposure.
Mesothelioma research in the Netherlands
Mesothelioma research in the Netherlands has received a boost from the Mesothelioma Applied Research Foundation (MARF), which has announced awards of almost US$1 million in additional research funding aimed at curing mesothelioma. Under this project, the Netherlands is part of a three-nation cross-disciplinary set of projects to accelerate research success against mesothelioma. The other nations involved are Australia and the United States.
Phase 1 of this project is currently underway and is focused on clinical trial of immunotherapy. The Erasmus Medical Center in the Netherlands is evaluating dendritic cells as a therapeutic adjuvant for treating mesothelioma in humans. This follows past successes with immunotherapy studies in mice that were very effective and also funded by MARF.
Future outlook
To predict future deaths from mesothelioma in the Netherlands, one has to take into account the following argument:
- Import of asbestos in the country increased from 1945 to 1974, and decreased noticeably only post-1978.
- Given the mean latency period of 40 years, the mesothelioma cases reported so far pertain to exposure in the 1960s.
- For several years after that, use of asbestos, hence exposure, first increased (up to 1974) and then decreased yet continued until 1993..
- So, future patients will mostly be workers whose first asbestos exposure happened in the 1970s, 1980s, and 1990s.
- The government of Netherlands banned asbestos as late as in 1993 when it became a political issue.
- Considering the mean latency period of 40 years, mesothelioma cases in the Netherlands can be expected to peak in the years to 2030.
- The number of cases (which was 325 in 2002) can be expected to reach 500 in 2017 and total mortalities close to 12,500 cases during 2000–2028.
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Summary
The Netherlands woke up to the tragedy of mesothelioma rather late. Its asbestos ban came in as late as in 1993 when it had become a political issue. No wonder, the country is experiencing one of the highest mesothelioma incidence rates in the world. Mesothelioma cases are believed to have been traditionally underreported. Reliable studies of the history of the disease until circa 2000 are therefore not possible. Yet, cohort modeling techniques of study indicate that the mean age at death is 62.9 years and the mean latency period is 40 years. This suggests that the mesothelioma death toll will touch about 12,500 cases in the 2000-2028 period.
On a more positive side, the Netherlands is part of a three-nation cross-disciplinary set of nine new projects researching mesothelioma. Dutch medical scientists are combining their efforts will scientists in Australia and the United States to advance prospects of early detection and better management, possibly cure, of the now hopelessly fatal disease. |
