Brenda K. Edwards, PhD

Mesotheliomas are uncommon in the United States, with an incidenceof about 3,000 new cases per year (or a risk of about 11 per million Americansper year). Incidence and mortality, however, are probably underestimated.Most are associated with asbestos, although some have arisen inports of prior radiation, and a reported association with simian virus (SV)40remains controversial. About 85% of mesotheliomas arise in the pleura,about 9% in the peritoneum, and a small percentage in the pericardiumor tunica vaginalis testis. The histology of about half of mesotheliomas isepithelial (tubular papillary), with the remainder sarcomatous or mixed.Multicystic mesotheliomas and well-differentiated papillary mesotheliomasare associated with long survival in the absence of treatmentand should be excluded from clinical trials intended for the usual rapidlylethal histologic variants of the disease. The median survival isunder a year, although longer median survivals for selected patients,particularly those with epithelial histology, have been reported in somecombined-modality studies. Recent randomized trials have shown significantimprovement in time to progression and survival for the additionof new antifolates to platinum-based chemotherapy.