Malignant pleural mesothelioma: an update on biomarkers and treatment

Although the insulating properties of asbestos have been known for millennia, the link between asbestos exposure and mesothelioma was not recognized until 1960, when it was first described in South African asbestos miners. The incidence of mesothelioma parallels asbestos usage with a latency of 20 to 40+ years; thus, patient numbers are declining in the United States but rising in the developing world. Radiation, genetics, and possibly simian virus 40 are less common causes. Diagnosis can be challenging, since the results of pleural fluid cytology testing are often negative despite repeated sampling. No staging system adequately predicts prognosis in the unresected patient. Newly described biomarkers, including soluble mesothelin-related peptide, megakaryocyte potentiation factor, and osteopontin, may predict which asbestos-exposed individuals will develop mesothelioma, and may prove useful in assessing response to treatment. Since surgery cannot eradicate all residual microscopic disease, a multimodality approach is encouraged. Metaanalysis suggests that pleurectomy/decortication may achieve outcomes similar to those of extrapleural penumonectomy. The standard first-line chemotherapy for unresectable disease is pemetrexed plus cisplatin. This combination improves response, survival, time to progression, pulmonary function, and disease-related symptoms. Carboplatin is often substituted, with similar results. Other active agents include raltitrexed, gemcitabine, and vinorelbine. Novel agents in clinical trials include inhibitors of the epidermal growth factor receptor, vascular endothelial growth factor, mesothelin, and histone deacetylases. Although disappointing results of early trials did not confirm promising preclinical data, recent studies have suggested that some novel agents may be effective. As we learn more about mesothelioma biology, molecularly targeted agents may become treatment options.