Cytogenetic and molecular genetic changes in malignant mesothelioma

Malignant mesothelioma (MM) results from the accumulation of a number of acquired genetic events, especially deletions, which lead to the inactivation of multiple onco-suppressor genes in a multistep cascade mechanism. Past asbestos exposure represents the major risk factor for MM, and the link between asbestos fibers and MM has been largely proved by several epidemiologic and experimental studies. Asbestos fibers induce DNA and chromosomal damage. Most MM cases have shown multiple chromosomal abnormalities. Chromosomal losses are more common than gains. The most common cytogenetic abnormality in MM is a deletion in 9p21, the locus of CDKN2A, a tumor suppressor gene (TSG). The deletion of CDKN2A is a negative prognostic factor in MM. Loss of TSG CDKN2A/p14(ARF) is also common in MM and mutations in NF2 occur in approximately half of the cases. Despite the ban on asbestos use in Western countries, the incidence of MM is increasing, and asbestos is still used in developing countries. This epidemiologic situation calls for further research. Ongoing studies are already applying high-throughput genomic profiling methods in MM. Genetic alterations observed in MM may be useful in differential diagnosis between lung cancer and MM, as diagnostic markers or therapeutic targets, and as indicators of premalignancy for primary prevention and health surveillance.