CONFIRM: a double-blind, placebo-controlled phase III clinical trial investigating the effect of nivolumab in patients with relapsed mesothelioma: study protocol for a randomised controlled trial

BACKGROUND

Mesothelioma is an incurable, apoptosis-resistant cancer caused in most cases by previous exposure to asbestos and is increasing in incidence. It represents a growing health burden but remains under-researched, with limited treatment options. Early promising signals of activity relating to both PD-L1- and PD-1-targeted treatment in mesothelioma implicate a dependency of mesothelioma on this immune checkpoint. There is a need to evaluate checkpoint inhibitors in patients with relapsed mesothelioma where treatment options are limited.

METHODS

The addition of 12 months of nivolumab (anti-PD1 antibody) to standard practice will be conducted in the UK using a randomised, placebo-controlled phase III trial (the Cancer Research UK CONFIRM trial). A total of 336 patients with pleural or peritoneal mesothelioma who have received at least two prior lines of therapy will be recruited from UK secondary care sites. Patients will be randomised 2:1 (nivolumab:placebo), stratified according to epithelioid/non-epithelioid, to receive either 240 mg nivolumab monotherapy or saline placebo as a 30-min intravenous infusion. Treatment will be for up to 12 months. We will determine whether the use of nivolumab increases overall survival (the primary efficacy endpoint). Secondary endpoints will include progression-free survival, objective response rate, toxicity, quality of life and cost-effectiveness. Analysis will be performed according to the intention-to-treat principle using a Cox regression analysis for the primary endpoint (and for other time-to-event endpoints).

DISCUSSION

The outcome of this trial will provide evidence of the potential benefit of the use of nivolumab in the treatment of relapsed mesothelioma. If found to be clinically effective, safe and cost-effective it is likely to become the new standard of care in the UK.

TRIAL REGISTRATION

EudraCT Number: 2016-003111-35 (entered on 21 July 2016); ClinicalTrials.gov, ID: NCT03063450 . Registered on 24 February 2017.

Asbestos-worker exposure, family disease

Family members, mostly female, can be at risk of asbestos-related disease as a result of the transfer of asbestos from the workplace to the home on the hair, boots and clothes of the worker. It is argued that in these cases the home should be recognised as an extension of the workplace and that the employer has a duty of care to contain and control the asbestos. Given these circumstances, the family member with the disease should be entitled to cover under the Accidence Compensation Legislation.

MesobanK UK: an international mesothelioma bioresource

Malignant pleural mesothelioma causes the greatest societal burden of all the asbestos-related diseases. Progress in better understanding tumour biology will be facilitated by the availability of quality-assured annotated tissue. MesobanK has been created to establish a bioresource of pleural mesothelioma tissue linked to detailed anonymised clinical data. When complete, the bioresource will comprise a 750-patient tissue microarray and prospectively collected tissue, blood and pleural fluid from 300 patients with mesothelioma. Twenty-six new cell lines have also been developed. MesobanK meets all appropriate ethical and regulatory procedures and has recently opened to requests for tissue and data.

[Health expenditures for cases of pleural mesothelioma]

Through the study of 65 cases of probable pleural mesothelioma currently under discussion in 4 criminal trials in the Lombardy Region, who died between 2002 and 2015, this study aimed to provide economical information regarding the health expenditures sustained by the Regional Health Service (RHS) for providing hospitalization, outpatient services and drugs to such patients. Health information regarding the services provided for the cases under study were electronically retrieved from the RHS information system. For each pleural mesothelioma case the costs (on average) were about 67,000 euros, 37,000 of which were spent after the date of diagnosis. Drugs formed the largest part of health expenditure (about 37,000 euros per person). Per capita expenditures showed a peak near (before and after) the date of diagnosis, rising when approaching the date of death and with increasing age of the patient, and did not vary with survival time. This information, reported for the first time in detail in this paper, will be useful for out-of-court agreements and for setting up reimbursement schemes, and describe per capita expenditures which are higher than estimations proposed in recent criminal trials in Italy and to those reported in the international literature.

Efficacy and cost of video-assisted thoracoscopic partial pleurectomy versus talc pleurodesis in patients with malignant pleural mesothelioma (MesoVATS): an open-label, randomised, controlled trial

BACKGROUND

Malignant pleural mesothelioma incidence continues to rise, with few available evidence-based therapeutic options. Results of previous non-randomised studies suggested that video-assisted thoracoscopic partial pleurectomy (VAT-PP) might improve symptom control and survival. We aimed to compare efficacy in terms of overall survival, and cost, of VAT-PP and talc pleurodesis in patients with malignant pleural mesothelioma.

METHODS

We undertook an open-label, parallel-group, randomised, controlled trial in patients aged 18 years or older with any subtype of confirmed or suspected mesothelioma with pleural effusion, recruited from 12 hospitals in the UK. Eligible patients were randomly assigned (1:1) to either VAT-PP or talc pleurodesis by computer-generated random numbers, stratified by European Organisation for Research and Treatment of Cancer risk category (high vs low). The primary outcome was overall survival at 1 year, analysed by intention to treat (all patients randomly assigned to a treatment group with a final diagnosis of mesothelioma). This trial is registered with ClinicalTrials.gov, number NCT00821860.

FINDINGS

Between Oct 24, 2003, and Jan 24, 2012, we randomly assigned 196 patients, of whom 175 (88 assigned to talc pleurodesis, 87 assigned to VAT-PP) had confirmed mesothelioma. Overall survival at 1 year was 52% (95% CI 41-62) in the VAT-PP group and 57% (46-66) in the talc pleurodesis group (hazard ratio 1·04 [95% CI 0·76-1·42]; p=0·81). Surgical complications were significantly more common after VAT-PP than after talc pleurodesis, occurring in 24 (31%) of 78 patients who completed VAT-PP versus ten (14%) of 73 patients who completed talc pleurodesis (p=0·019), as were respiratory complications (19 [24%] vs 11 [15%]; p=0·22) and air-leak beyond 10 days (five [6%] vs one [1%]; p=0·21), although not significantly so. Median hospital stay was longer at 7 days (IQR 5-11) in patients who received VAT-PP compared with 3 days (2-5) for those who received talc pleurodesis (p<0·0001).

INTERPRETATION

VAT-PP is not recommended to improve overall survival in patients with pleural effusion due to malignant pleural mesothelioma, and talc pleurodesis might be preferable considering the fewer complications and shorter hospital stay associated with this treatment.

FUNDING

BUPA Foundation.

Estimating the social cost of respiratory cancer cases attributable to occupational exposures in France

PURPOSE

The objective of this article was to estimate the social cost of respiratory cancer cases attributable to occupational risk factors in France in 2010.

METHODS

According to the attributable fraction method and based on available epidemiological data from the literature, we estimated the number of respiratory cancer cases due to each identified risk factor. We used the cost-of-illness method with a prevalence-based approach. We took into account the direct and indirect costs. We estimated the cost of production losses due to morbidity (absenteeism and presenteeism) and mortality costs (years of production losses) in the market and nonmarket spheres.

RESULTS

The social cost of lung, larynx, sinonasal and mesothelioma cancer caused by exposure to asbestos, chromium, diesel engine exhaust, paint, crystalline silica, wood and leather dust in France in 2010 were estimated at between 917 and 2,181 million euros. Between 795 and 2,011 million euros (87-92%) of total costs were due to lung cancer alone. Asbestos was by far the risk factor representing the greatest cost to French society in 2010 at between 531 and 1,538 million euros (58-71%), ahead of diesel engine exhaust, representing an estimated social cost of between 233 and 336 million euros, and crystalline silica (119-229 million euros). Indirect costs represented about 66% of total costs.

CONCLUSION

Our assessment shows the magnitude of the economic impact of occupational respiratory cancers. It allows comparisons between countries and provides valuable information for policy-makers responsible for defining public health priorities.

Post-occupational health surveillance of asbestos workers

BACKGROUND

Italian law requires an extensive health surveillance of workers after cessation of their employment status in the case of occupational exposure to carcinogens, including asbestos. Nonetheless, Italian law does not specify the timeframe of these clinical checks, nor who has financial and organizational responsibility for this surveillance. A literature search confirmed a lack of consensus around the objectives and methods to follow up workers with past occupational exposure to asbestos.

OBJECTIVES

To develop an updated evidence-based methodology for an appropriate health surveillance programme.

METHODS

We present an overview of the field experience developed by the Veneto Region from 2000 to 2011, and new studies that could contribute to establishing a national policy for the medical surveillance of workers with past asbestos exposure.

RESULTS

There were three specific topics: (1) definition of a reliable method to identify asbestos workers (through multiple sources and procedures that meet current confidentiality regulations); (2) detection of asbestos fibres in biological media (to support the etiological diagnosis of asbestos-related diseases); (3) creation of a national protocol of health surveillance (through the assessment of policies developed by other Regions in this field, and recruiting from these regions a cohort of past-exposed workers: the epidemiological study should offer relevant suggestions for specific surveillance approaches, based on either estimated cumulative asbestos exposure or detection of x-ray patterns of pleural plaques and/or asbestosis).

CONCLUSIONS

These studies will support the Regions in setting up health care policies directed at workers with past asbestos exposure.

Compensation of pleural mesothelioma in France: data from the French National Mesothelioma Surveillance Programme

BACKGROUND

The aim of this study was to determine the rates of compensation awarded to patients presenting with pleural mesothelioma and factors linked to such compensation in France.

METHODS

The study population consisted of 2,407 patients presenting with pleural mesothelioma, recorded by the National Mesothelioma Surveillance Programme between January 1, 1999 and December 31, 2009. Analysis of claims for recognition as "occupational disease" (OD) and claims for compensation by the Compensation Fund for Asbestos Victims (FIVA) were analyzed.

RESULTS

Approximately 30% of subjects presenting with pleural mesothelioma, affiliated to the General National Health Insurance fund, neither sought recognition as an OD nor claimed for FIVA compensation. Gender, age at diagnosis, type of health insurance, and socio-professional category influence the likelihood of patients presenting with mesothelioma seeking compensation for this disease.

CONCLUSIONS

Results show an under-compensation of pleural mesothelioma as OD and by the FIVA in France.

[The effectiveness of compensation system for mesotheliomas due to occupational exposure to asbestos and determinants for requests and awards: an evaluation based on record-linkage between the Veneto Mesothelioma Register and the claims and compensations recorded by the National Insurance Institute (INAIL)]

AIM

To determine the rate of requests for compensation and of compensations awarded for mesothelioma cases due to occupational exposure to asbestos; to identify factors that may influence the outcome; to provide an appreciation of the amount of compensation.

DESIGN AND MAIN OUTCOME MEASURES

Record-linkage study at individual level between the new cases of mesothelioma occurred among the residents of the Veneto Region (Northern Italy) between 1999- 2007 and the file of the Insurance Institute, with individual data on all claims and compensations. Adjusted logistic regression models were used to estimated the association between submitting claims and obtaining an award and socio-demographic and other characteristics.

RESULTS

349 on 499 mesotheliomas considered to be due to occupational exposure to asbestos submitted a claim (70% of those of occupational origin) and 72%of claims were accepted. The welfare system covers only 35%of mesothelioma occurred. The probability of submitting and obtaining a claim was associated with gender, cancer site, age at diagnosis, vital status, and residence or local office in charge of the evaluation. A strong discrimination against women is observed. If exposure to asbestos at work was due to a direct manipulation of asbestos, claims were more easily accepted.As a consequence,mesothelioma occurred among construction workers, the occupational activity at the origin of the largest number of occurring mesotheliomas, are more frequently rejected.When submitted by a relative, the lag between a request for compensation and the decision is on average of about two years.

CONCLUSION

This is the first study in Italy using a record-linkage method and was made possible thanks to a population based mesothelioma Register and the availability of memorized information of the Insurance Institute.The welfare system shown clear limitations and there is the need for more appropriate strategies.

Asbestos-related occupational cancers compensated under the Industrial Accident Compensation Insurance in Korea

Compensation for asbestos-related cancers occurring in occupationally-exposed workers is a global issue; this is also an issue in Korea. To provide basic information regarding compensation for workers exposed to asbestos, 60 cases of asbestos-related occupational lung cancer and mesothelioma that were compensated during 15 yr; from 1993 (the year the first case was compensated) to 2007 by the Korea Labor Welfare Corporation (KLWC) are described. The characteristics of the cases were analyzed using the KLWC electronic data and the epidemiologic investigation data conducted by the Occupational Safety and Health Research Institute (OSHRI) of the Korea Occupational Safety and Health Agency (KOSHA). The KLWC approved compensation for 41 cases of lung cancer and 19 cases of mesothelioma. Males accounted for 91.7% (55 cases) of the approved cases. The most common age group was 50-59 yr (45.0%). The mean duration of asbestos exposure for lung cancer and mesothelioma cases was 19.2 and 16.0 yr, respectively. The mean latency period for lung cancer and mesothelioma cases was 22.1 and 22.6 yr, respectively. The major industries associated with mesothelioma cases were shipbuilding and maintenance (4 cases) and manufacture of asbestos textiles (3 cases). The major industries associated with lung cancer cases were shipbuilding and maintenance (7 cases), construction (6 cases), and manufacture of basic metals (4 cases). The statistics pertaining to asbestos-related occupational cancers in Korea differ from other developed countries in that more cases of mesothelioma were compensated than lung cancer cases. Also, the mean latency period for disease onset was shorter than reported by existing epidemiologic studies; this discrepancy may be related to the short history of occupational asbestos use in Korea. Considering the current Korean use of asbestos, the number of compensated cases in Korea is expected to increase in the future but not as much as developed countries.

Cost-effectiveness of pemetrexed plus cisplatin: malignant pleural mesothelioma treatment in UK clinical practice

OBJECTIVES

Findings from the largest randomized phase III trial in patients with unresectable malignant pleural mesothelioma (EMPHACIS study; n = 448) were used to examine the cost-effectiveness of pemetrexed plus cisplatin therapy versus cisplatin monotherapy in patients with the disease. The cost-effectiveness of pemetrexed/cisplatin versus alternative treatments was also examined.

METHODS

Two cost-effectiveness analyses were designed to model best survival outcome over time for a number of patient cohorts. First, trial-based patient-level data were utilized and resource use was costed for the study arm and comparator. A second cost-effectiveness analysis then compared the mean costs and outcomes associated with pemetrexed/cisplatin with the most commonly used (unlicensed) regimens in the United Kingdom-mitomycin-C, vinblastine, and cisplatin (MVP); vinorelbine; and active symptom control-using trial-based data and data extrapolated from a review of the literature.

RESULTS

The total pemetrexed/cisplatin cost per patient varied between pound8779 and pound9020 for all cohorts studied in model 1. Average life-years gained per patient were between 0.20 and 0.28. Quality-adjusted life-years, based on mean and median survival, ranged from 0.13 to 0.31. Incremental cost per life-year gained and quality-adjusted life-year ratios, using both mean and median survival, ranged from pound20,475 to pound68,598. The second cost-effectiveness analysis resulted in ratios ranging from pound14,595 to pound32,066.

CONCLUSIONS

Pemetrexed/cisplatin demonstrated acceptable cost-effectiveness when compared with cisplatin monotherapy and alternative treatments commonly used in UK clinical practice.

Management options for malignant pleural mesothelioma: clinical and cost considerations

Malignant pleural mesothelioma (MPM) is a resistant form of lung cancer that is often related to prior asbestos exposure. While surgical resection and radiotherapy techniques have been refined in recent years, neither has been proven to significantly extend patient survival compared with untreated controls. Until the release of pemetrexed in 2004, even combination chemotherapy regimens often resulted in a response rate of <20%. A recent phase III trial documented a 41.3% response rate for cisplatin plus pemetrexed. In the future, new multimodality regimens featuring novel targeted therapies directed against molecular targets, such as the vascular endothelial growth factor, hold the greatest promise for improved outcomes in MPM. The standard radiographic assessment of response to MPM therapy remains a poor surrogate for clinically relevant endpoints such as median survival. Furthermore, it is not currently known whether aggressive multimodality treatment for MPM will improve survival or quality of life above and beyond symptomatic care. Ongoing clinical trials are comparing chemotherapy and surgery with supportive care in an effort to define the role of different therapies in MPM. MPM treatment is a costly public health issue; after efficacy is proven, additional studies are needed to measure the cost effectiveness of MPM treatment regimens.

[Compensation of malignant mesothelioma as an occupational disease in Lower Normandy, from 1995 to 2002]

BACKGROUND

Despite the close relation between occupational exposure to asbestos and malignant mesothelioma, the compensation of this disease is still far from being the rule. The objective of this study is to assess the compensation process of all the cases of occupational mesothelioma recorded by the regional mesothelioma registry between September 1995 and August 2002, and to make suggestions for improvement of the compensation of future cases.

METHODS

Lifetime exposure to asbestos was assessed for each of the 141 mesothelioma cases observed in Lower Normandy during this time period, and 105 cases could be related to a possible, probable, or very probable occupational exposure to this mineral. Data about notification and compensation of these occupational diseases were gathered with the help of all health insurance organisms concerned.

RESULTS

Except for five cases in which insurance conditions did not allow any compensation, compensation of occupational mesothelioma occurred in 85% of the cases. This high rate was probably the result of the existence of an early asbestos industry in this region, and of the particular awareness of the Norman population about asbestos-related diseases, as well as of the epidemiological follow-up of mesothelioma in Lower Normandy. When notified for compensation, all cases but one were actually compensated, and the lag-time between notification and compensation proved to decrease since 1995, with an average delay reaching 91,1 days in 2002. Patients who did not report their disease were older than those who did, and the lack of knowledge of medical practitioners about compensation procedures seems to be an important matter in this issue.

CONCLUSION

In order to improve the rate of compensation of occupational malignant mesothelioma cases, information about the usual occupational origin of the disease should be delivered systematically to the general practitioner of each patient. This could be done by pathologists, when they diagnose malignant mesothelioma, and/or by medical examiners when sickness benefits are sought, or even by the epidemiological center of death causes (INSERM, CépiDc), for the beneficiaries of patients who died from malignant mesothelioma.

Mesothelioma

Mesothelioma is one of the most aggressive human malignancies. In this article the research team of Dr. Michele Carbone reviewed the most significant scientific and medical advances in understanding the pathogenesis of mesothelioma and some novel preventive and therapeutic approaches that are being developed. The public health and litigation issues, together with the economics surrounding mesothelioma research and therapy are also discussed.

Mesothelioma research as a social issue

From a social perspective, a number of factors may explain why mesothelioma research has tended to be an "orphan." The disease has a relatively low incidence compared to other cancers, the average age of mesothelioma patients is relatively high, the disease is expected to decline "on its own," and the disease has long been considered intractable to therapy. However, there are persuasive counterpoints to these factors. Additionally, other aspects of the mesothelioma tragedy persuasively justify societal investment in mesothelioma research. Social justice is among the strongest of these reasons, but paradoxically, it also significantly impedes progress. Mesothelioma patients' contribution to society is another strong justification, although also not without problems. Finally, optimal utilization of resources provides a very pragmatic, and potentially very forceful, justification for increased societal investment in mesothelioma research.

The Economic Costs of Health Service Treatments for Asbestos-Related Mesothelioma Deaths

This article explores the complex and neglected picture of occupational and environmental disease healthcare costs specifically relating to asbestos. Diagnosed mesothelioma cases in Scotland in one calendar year were used to investigate the subject in greater depth. Data from UK sources on asbestos disease types recorded in 2000 and their disease treatment costs were obtained. Acute care economic costs of these diseases are estimated. One hundred and twenty diagnosed, recorded, and treated cases of asbestos-related diseases occurred in 2000 in Scotland. Mesothelioma accounted for 100 cases and directly cost Scottish National Health Service hospitals an estimated 942,038 pounds. The estimated UK figure in 2000 was at least 16,014,646 pounds because official figures for diagnosed and recorded deaths from mesothelioma are running at over 1700 a year with rises predicted for 2010 of 2000 deaths. By 2003, 50,000 people in the UK had died from diagnosed and recorded mesothelioma since records began. Earlier disease treatment costs would have been significantly lower than those in 2000 but, at 2000 prices, cost to the UK was roughly 471,019,000 pounds in acute hospital expenditure. Figures for primary care costs, including caregiver costs, are incomplete or unknown. These disease costs are substantial and have some international generalizability. Treatment patterns and costs vary greatly. Many lung cancer cases due to asbestos exposure occur globally for each mesothelioma case. Hence figures provided in this article are certain to be gross underestimates of the total health service and personal economic costs of asbestos illness and treatment in Scotland.

Compensation of asbestos victims in France

The alarming development of pathologies linked to asbestos led to the creation in France of two funds to indemnify the victims of asbestos-related illnesses: the FCAATA (Fund for asbestos workers who take early retirement), which compensates for their reduced life expectancy, and the FIVA (Indemnification fund for asbestos victims) which ensures full compensation for harm suffered by asbestos victims.

Mesothelioma: risk apportionment among asbestos exposure sources

The mesothelioma epidemic in the United States, which peaked during the 2000-2004 period, can be traced to high-level asbestos exposures experienced by males in occupational settings prior to the full recognition of the disease-causing potential of asbestos and the establishment of enforceable asbestos exposure limits by the Occupational Safety and Health Administration (OSHA) in 1971. Many individuals diagnosed with mesothelioma where asbestos has been identified as a contributing cause of the disease have filed claims seeking compensation from asbestos settlement trusts or through the court system. An individual with mesothelioma typically has been exposed to asbestos in more than one setting and from more than one asbestos product. Apportioning risk for mesothelioma among contributing factors is an ongoing problem faced by occupational disease compensation boards, juries, parties responsible for paying damages, and currently by the U.S. Senate in its efforts to formulate a bill establishing an asbestos settlement trust. In this article we address the following question: If an individual with mesothelioma where asbestos has been identified as a contributing cause were to be compensated for his or her disease, how should that compensation be apportioned among those responsible for the asbestos exposures? For the purposes of apportionment, we assume that asbestos is the only cause of mesothelioma and that every asbestos exposure contributes, albeit differentially, to the risk. We use an extension of the mesothelioma risk model initially proposed in the early 1980s to quantify the contribution to risk of each exposure as a percentage of the total risk. The percentage for each specific discrete asbestos exposure depends on the start and end dates, the intensity, and the asbestos fiber type for the exposure. We provide justification for the use of the mesothelioma risk model for apportioning risk and discuss how to assess uncertainty associated with its application.

Justice for asbestos victims and the politics of compensation: the French experience

This paper presents the history of asbestos mining and manufacture in France, the strategies of the multinational asbestos firms to become major international participants, the failures of occupational health and safety that allowed an epidemic of asbestos-related diseases to occur, and the important social movement of the victims of asbestos exposure. The asbestos industry thrived in France until the health effects of asbestos exposure were made public. At that time, the industry had already moved its mining and manufacture to developing countries, where they were able to take advantage of limited regulation and enforcement of occupational and environmental laws. The author analyzes the compensation systems that were approached with varying degrees of success by the victims of asbestos exposure. France banned all manufacture and use of asbestos in 1997, and in the years that have followed, it has enjoyed many successes in achieving compensation for asbestos victims.

Asbestos in Belgium: use and abuse

It took 50 years for Belgium to recognize asbestosis; mesothelioma and lung cancer were recognized as occupational diseases caused by asbestos in 1982 and 1999, much later than in neighboring countries. Only salaried workers can claim compensation from the Occupational Diseases Fund. The right to reparation is thus denied to most victims because many have been self-employed: mechanics, electricians, painters, roofers, carpenters, plumbers, etc. Compensation was also denied to people who became ill through exposures to the workclothes of family members or pollution from asbestos factories near their homes. The main obstacles facing asbestos victims are legal and judicial. For instance, an employer is not liable, even for gross negligence. Victims are not allowed to claim if 20 years have passed since their exposures to asbestos. Changes in Belgian legislation are sorely needed.

Apportionment in asbestos-related disease for purposes of compensation

Workers' compensation systems attempt to evaluate claims for occupational disease on an individual basis using the best guidelines available to them. This may be difficult when there is more than one risk factor associated with the outcome, such as asbestos and cigarette smoking, and the occupational exposures is not clearly responsible for the disease. Apportionment is an approach that involves an assessment of the relative contribution of work-related exposures to the risk of the disease or to the final impairment that arises for the disease. This article discusses the concept of apportionment and applies it to asbestos-associated disease. Lung cancer is not subject to a simple tradeoff between asbestos exposure and smoking because of the powerful biological interaction between the two exposures. Among nonsmokers, lung cancer is sufficiently rare that an association with asbestos can be assumed if exposure has occurred. Available data suggest that asbestos exposure almost invariably contributes to risk among smokers to the extent that a relationship to work can be presumed. Thus, comparisons of magnitude of risk between smokers and nonsmokers are irrelevant for this purpose. Indicators of sufficient exposure to cause lung cancer are useful for purposes of establishing eligibility and screening claims. These may include a chest film classified by the ILO system as 1/0 or greater (although 0/1 does not rule out an association) or a history of exposure roughly equal to or greater than 40 fibres/cm3 x y. (In Germany, 25 fibres/cm3 x y is used.) The mere presence of pleural plaques is not sufficient. Mesothelioma is almost always associated with asbestos exposure and the association should be considered presumed until proven otherwise in the individual case. These are situations in which only risk of a disease is apportioned because the impairment would be the same given the disease whatever the cause. Asbestosis, if the diagnosis is correct, is by definition an occupational disease unless there is some source of massive environmental exposure; it is always presumed to be work-related unless proven otherwise. Chronic obstructive airways disease (COAD) accompanies asbestosis but may also occur in the context of minimal parenchymal fibrosis and may contribute to accelerated loss of pulmonary function. In some patients, particularly those with smoking-induced emphysema, this may contribute significantly to functional impairment. An exposure history of 10 fibre x years is suggested as the minimum associated with a demonstrable effect on impairment, given available data. Equity issues associated with apportionment include the different criteria that must be applied to different disorders for apportionment to work, the management of future risk (eg. risk of lung cancer for those who have asbestosis), and the narrow range in which apportionment is really useful in asbestos-associated disorders. Apportionment, attractive as it may be as an approach to the adjudication of asbestos-related disease, is difficult to apply in practice. Even so, these models may serve as a general guide to the assessment of asbestos-related disease outcomes for purposes of compensation.

[Diagnosis of malignant pleural mesothelioma and asbestosis]

The incidence of malignant mesothelioma, the main consequence of exposure to asbestos, will increase considerably in the Netherlands in the coming decades. In the next 35 year, some 20,000 people will die from malignant mesothelioma. The diagnosis of malignant pleural mesothelioma in practice is based on histological examination in about 80%, on cytological examination in 15% and on other forms of examination, e.g., high resolution computer tomography (HRCT), in 6% of the cases. Using a combination of various noninvasive methods, such as anamnesis, physical and röntgenologic examination, HRCT and spirometry, the diagnosis of asbestosis is made erroneously in 5% of the patients examined. With regard to allowance of financial compensation to patients with pleural mesothelioma and asbestosis, a part is played by the fact that views differ internationally concerning the criteria on which the diagnosis should be based. For mesothelioma cytologic and histologic examination are the most important. For asbestosis, the Health Council considers HRCT as crucial, if necessary supplemented by histological examination, plus a history of exposure to asbestos and pulmonary dysfunction. In mesothelioma cytological and histological examination are the most important.

[Use of occupational disease benefits]

Persons with pleuramesothelioma were studied to find out the share receiving occupational injury benefit from the National Insurance Scheme. This disease, caused by inhaling asbestos, was chosen because it has been estimated that between 70 and 80 per cent of persons with pleuramesothelioma fulfil the criteria for compensation. During the period 1970-93, 662 men and 104 women were recorded as having this disease. Up to June 1996, the National Insurance Administration had considered the cases of only 163 men, and no women. A further 25-30 patients may have filed claims with the local national insurance office. This implies that, overall, maximum one third of those entitled to occupational injury benefit have received it. The fraction would probably be even lower in the case of diseases where the association with occupation is less certain. It is recommended that national disease registries, such as the Cancer Registry, should report possible cases of occupational disease to the National Insurance Administration.