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"Pleurale plaques" voorspelt asbestgerelateerde longkanker

15-03-2005 00:00

Bij mannen die geen asbestose ("stoflongen" door asbest) hebben komt asbestgerelateerde longkanker vaker voor dan was verwacht. "Pleurale plaques" (een goedaardige verdikking van het borstvlies) is een belangrijke voorspeller van asbestgerelateerde longkanker. Deze nieuwe inzichten komen uit een onderzoek van meer dan 10 jaar onder 4000 Amerikaanse mannen die aan asbest blootgesteld zijn geweest.
Increased lung cancer among asbestos workers with no evidence of asbestosis

Below, details of a new paper on asbestos and lung cancer, forwarded by Frank Mirer, director of health and safety at the US autoworkers' union UAW.

The paper looks important for two reasons - firstly because of the lung cancer without asbestosis finding - in some jurisdictions official workers' compensation schemes only pay benefits to lung cancer sufferers who also have asbestosis.

Secondly, the paper is valuable because it establishes the importance of pleural plaques as a predicator of lung cancer. Insurers and employers in the UK, USA and elsewhere are at this moment trying to play down the significance of the association between pleural plaques and asbestos.

Their motive is to reduce their compensation liabilities. One consequence of this might be a lower likelihood of diagnosis of pleural plaques (many of the health checks are the result of compensation inquiries), so we could lose our early warning system or "sentinel health event" for an enormous lung cancer risk. In the UK at the moment there are several thousand asbestos related lung cancers ever year - the combined annual death toll for asbestos related lung cancers and mesothelioma is expect to reach 10,000 within 20 years.

Yours, Rory

Rory O'Neill

International Federation of Journalists



Increased lung cancer among asbestos workers with no evidence of asbestosis

A very important study giving quantitative measures of risks of asbestos exposure was just published. The study is an important data source for evaluating medical criteria for compensation of asbestos exposed workers, now being discussed in Congress.

The project was a chemoprevention test whether Vitamin A - an antioxidant - protected against future effects of past asbestos exposure. The investigators had enrolled over 4,000 asbestos workers and followed them for over a decade. Recruitment must have been a huge task The chemoprevention study was terminated because Vitamin A increased the risk of lung cancer.

The study confirmed excessive rates of lung cancer among men with radiographic asbestosis, but also among workers with no evidence of asbestosis. Among workers with no evidence of asbestosis at baseline, men with more than 40 years' exposure in high-risk trades had a risk approximately fivefold higher than men with 5-10 years. Pleural plaques on the baseline x-ray and abnormal baseline flow rate were strong independent predictors of subsequent lung cancer.

Hopefully, people with access to the full text of this study will comment further.

American Journal of Epidemiology 2005 161(3):260-270.

Predictors of Lung Cancer among Asbestos-exposed Men in the µ-Carotene and

Retinol Efficacy Trial

Mark R. Cullen1 , Matt J. Barnett2, John R. Balmes3, Brenda Cartmel1, Carrie

A. Redlich1, Carl A. Brodkin4, Scott Barnhart4, Linda Rosenstock5, Gary E.

Goodman2,6, Sam P. Hammar7, Mark D. Thornquist2 and Gilbert S. Omenn8,9



Despite numerous published studies, debate continues regarding the risk of developing lung cancer among men exposed occupationally to asbestos, particularly those without radiographic or functional evidence of asbestosis. The µ-Carotene and Retinol Efficacy Trial (CARET), a study of vitamin supplementation for chemoprevention of lung cancer, has followed 4,060 heavily exposed US men for 9-17 years. Lung cancer incidence for 1989-2002 was analyzed using a stratified proportional hazards model. The study confirmed excessive rates of lung cancer among men with radiographic asbestosis. Comparison of study arms revealed a strong, unanticipated synergy between radiographic profusion category and the active intervention. In the large subgroup of men with normal lung parenchyma on chest radiograph at baseline, there was evidence of exposure-related lung cancer risk: Men with more than 40 years' exposure in high-risk trades had a risk approximately fivefold higher than men with 5-10 years, after adjustment for covariates. The effect in these men was independent of study intervention arm, but pleural plaques on the baseline radiograph and abnormal baseline flow rate were strong independent predictors of subsequent lung cancer. Residual confounding by subclinical asbestosis, exposure to unmeasured lung carcinogens, or differences in smoking are unlikely to explain these observations better than a carcinogenic effect of asbestos per se.