The genetics of cancer heterogeneity and mesothelioma.

Diffuse mesothelioma is an invasive cancer that originates from the cells in the smooth tissue lining (serosal membrane) that surrounds various body cavities. While most cases originate in the pleural lining of the thoracic cavity, a subset primarily involves the peritoneum or, rarely, the pericardium or the tunica vaginalis. Advances in molecular biology have established that cancer heterogeneity is common across a wide variety of histogenetically diverse neoplasms and that 'mesothelioma' as a disease is the same. It is increasingly evident that age, sex, and anatomic site-specific variations do exist which are often driven by recognized and recurrent mutations although a high degree of inter- and intra-tumor heterogeneity is present, and this is reviewed. Diverse patterns of disease exist with respect to clinical, radiologic, pathologic findings and these are driven by unique molecular events, the mechanisms and origin of which are increasingly determined to be due to stochastic events. Consequently, mesothelioma has not only considerable radiologic, macroscopic, and microscopic heterogeneity, but includes multiple distinct genetic entities. Most mesotheliomas are characterized by recurrent mutations in tumor suppressor genes and epigenetic regulators, including