Chemoprevention of asbestos-linked cancers: a systematic review

Asbestos has been used extensively and, in spite of many countries having banned most of its uses, professional, domestic and environmental exposure has not ceased worldwide. Inhaled asbestos fibers can lead to malignant mesothelioma, lung cancer and non-cancerous conditions, while the substance persists indefinitely in the lung and pleural tissue, resulting in continuous damage. Exposed individuals may be offered medical surveillance or compensation, but nothing is currently being done to lower their specific cancer risk: chemoprevention seems a promising approach. A web search and a PubMed review of the literature on chemoprevention trials in individuals exposed to asbestos have been conducted. Forty-six articles on five projects were found and newly reviewed but, surprisingly, no novel trials have been set up for twenty years, although considerable advances have been gained in cancer chemoprevention. A re-consideration of possibilities offered by chemoprevention should be encouraged. New trials based on the most recently characterized molecules should be planned, taking into account specific issues such as the need for a very large number of participants and a long follow up or, alternatively, the use of biomarkers as surrogate endpoints. The long latency of asbestos related diseases may offer delayed intervention opportunities. The lack of chemoprevention trials for asbestos exposure highlights the urgent need for research in this field.