Facts, rumours and speculations about the mesothelioma epidemic

The paper by Giang et al.1 demonstrates that information on mesothelioma and other asbestos-related diseases is hard to find, and not only for Asia. If one visits the CancerMondial website (http://www-dep.iarc.fr/), several international databases can be consulted but none of them feels obliged to include a separate entity for mesothelioma. The apparent absence of reliable data comes with a tendency to ignore or exaggerate the asbestos problem. Several studies predicted an epidemic of mesothelioma patients, with an annual peak for Western Europe of 20 000 cases around the year 2020.2 Among the countries with the highest incidence rates are Australia, the Netherlands and the UK. For Australia, an annual peak of 700 cases was predicted for the year 2010.3 For the Netherlands, an annual peak was forecasted for the year 2025 but that estimate was later amended to 2017.4 Recent data suggest that these predictions were overrated and that the peak has already been crossed (Fig. 1). For Australia, a maximum number of 649 was observed in 2003, and for the Netherlands, a peak number of 501 was recorded in 2005. Statistics from France (http://www.invs.sante.fr) and Belgium (http://www.kankerregister.be) demonstrate similar patterns. For the UK, an annual peak of 2200 patients was predicted for the year 2013.5 That prediction was recently substantiated with enhanced statistical methods and the latest data.6 Incidence* of mesothelioma in Australia and the Netherlands. *Data sources: Netherlands Cancer Registry (http://www.ikcnet.nl), Safe Work Australia (http://www.safeworkaustralia.gov.au); y axis are actual numbers. () Netherlands; () Australia. Incidence and mortality figures show similar results because malignant mesothelioma is still a fatal disease with a median overall survival of 8–12 months. One of the main reasons to develop a screening programme for mesothelioma would be to initiate therapy at an earlier stage than is currently the case and improving hereby the outcome.7 This assumes that therapy is more effective if given early. The early detection of mesothelioma (while still asymptomatic) is consequently desirable, but also troublesome because of the lack of accurate screening tools, the low prevalence of mesothelioma and its long latency period. In the past, several programmes have been conducted to screen asbestos-exposed individuals for lung disease with annual CXR. Besides demonstrating the presence of benign asbestos-related diseases, these modalities have not proven to be effective at detecting early malignancies.8 CT has a superior sensitivity, and its use in screening has been examined in several large-scale studies (Table 1).9-13 Results predominantly illustrate the low prevalence of mesothelioma, and the high background noise (non-calcified nodules) in asbestos-exposed populations. In addition, the standardization of reading both CXR and CT has proven to be difficult, while the cost and radiation doses represent other problematic issues. PET and MRI are currently not applied in screening, and their cost is likely to be prohibitive. Altogether, it is now generally accepted that the use of imaging has not made any impact on the early detection of mesothelioma, and their use is not recommended by the different (inter)national guidelines. The biomarker serum mesothelin has been evaluated by several authors.14, 15 Altogether, their disappointing results are neither in favour of incorporating serum mesothelin in screening for mesothelioma. Traditional treatment options were little effective and it took until recently before the first randomized controlled trials for mesothelioma were published, showing a survival benefit with a median of 2 months for patients treated with a palliative antifolate-cisplatin combination.16, 17 One year later, a plea was made to include more patients in clinical trials, anxious that incidence rates would fall as a result of preventive measures.18 The value of multimodality treatment including surgery and radiotherapy is still unknown and there is an urgent need for new treatment options to be tested in clinical trials, but time may be getting short. As the incidence appears to be on its return in western countries, the patient population is ageing and many elderly patients are not fit enough to stand toxic treatment because of comorbidities or poor performance status. It will take another 50 years before mesothelioma becomes a rare disease. Apart from the situation in Asia, people working in demolition or maintenance industry are still getting exposed to asbestos fibres and to help those future mesothelioma patients, we assent that inclusion in clinical trials should be seriously considered. Financial support should be secured, for example through charities, scientific boards, health and social security organizations, to assure that academic research can independently test real innovations and valuable time and resources are not wasted on systemic therapy trials in biomarker-unselected patients, with dubious end-points and me-too drugs. Whether we actually need data about ARD in Asia, or other parts of the world, is up to discussion. With the vast amount of evidence about the carcinogenic nature of asbestos, regulatory authorities should not wait for confirmations concerning their own region or country. As soon as the incidence rates start to rise, the mesothelioma epidemic is already beyond control. For the sane minded, no further research or data is needed to conclude that asbestos use should be banned and protective measures need to be taken when dealing with asbestos containing products. However, to influence regulatory authorities international data should be readily available to demonstrate the results of former negligence.