Asbestos Exposure Screening

David M. Quillen, MD

Disclosures

October 08, 2004

Question

Which screening tests would you recommend for a patient exposed to asbestos? Does the approach to screening change if there are abnormalities on chest x-ray?

Response from David M. Quillen, MD

"Asbestos" is a general term for fibrous materials that are mined and then used for their thermal and acoustic properties. There are a number of different mineral types of asbestos, but all can cause asbestosis, the progressive fibrotic disease of the lungs. Asbestos minerals had been manufactured into more than 3000 products and represent one of the most common environmental hazards.[1] Asbestos products have finally been banned, but millions of workers have been exposed. Many of these exposed individuals may develop asbestosis or related cancers, mesothelioma being the most notorious.

All clinicians should consider the following basic facts about asbestos exposure. The rate of lung cancer among asbestos-exposed workers is no higher than that of nonexposed populations. What is different is the rate of mesothelioma, which is much higher in the asbestos-exposed group. Also, the larger the asbestos exposure, the greater the risk. Finally, asbestos-related cancers generally do not develop without the presence of tobacco use.

A screening test needs to have 2 important qualities. The first is the ability to provide benefit for those being screened; this generally means an increased life expectancy, but also encompasses the ability to identify the disease (in this instance, lung cancer) in a stage at which it can be treated, with the progression changed and mortality reduced. The second quality is that the test should not be so dangerous or painful that the risks of the test exceed any benefit.

Screening for lung cancer in general has been disappointing. Recently Bach and colleagues[2] conducted a very nice review of 13 clinical trials that studied low-dose CT scan or chest x-ray and sputum cytology. Their conclusion was that chest x-ray and sputum cytology were not good screening tests. Low-dose CT scan has demonstrated promise, but needs further evaluation before it can be generally recommended.

At this point in time, given the controversy, there really is not a recommended and strongly supported screening protocol for asbestos-exposed workers. However, if I had a patient with an asbestos exposure history and a smoking history with an abnormal chest x-ray, I would order a CT scan and refer the patient to a pulmonary specialist for evaluation and probably for bronchoscopy. For more information on asbestos exposure, the National Institutes of Health has a good online resource (http://www.nlm.nih.gov/medlineplus/asbestos.html).

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