[Prognosis, staging and therapy of malignant pleural mesothelioma]

Prognosis of pleural mesothelioma remains dismal. Regardless of the modality employed median survival ranges between 6 and 12 months, only 20% of patients survive 1 year. In 1996 the International Mesothelioma Interest Group (IMIG) published a widely accepted staging system. So far there is no effective standard therapy. Even very aggressive therapies do not basically influence the course of the disease.

Despite numerous single-agent and combination chemotherapy trials no standard regimen could be found. Few agents yield reproducible response rates above 20%. The majority of the trials are inconclusive according to statistical criteria, as subject numbers are insufficient to prove or deny effectiveness. It also remains obscure in which stage of the disease patients may benefit from chemotherapy because of a lack of analysis of response rates within different stages. Striking is the lack of sufficient studies analyzing patients' quality of life treated with often very toxic regimens.

Systemic administration of interferons alone or in combination with chemotherapeutic agents did not result in higher response rates or prolonged median survival. In very early stages of the disease patients may have limited benefit from intracavitary, local administration of gamma-interferon.

Mere surgical procedures as extrapleural pneumonectomy or pleurectomy/decortication have been left in favor of multimodality approaches. Due to careful patient selection and improved operation techniques mortality could be reduced. Neither chemotherapy, radiotherapy nor photodynamic therapy can prevent local relapse which occurs in the majority of patients.

The effectiveness of primary radiation therapy remains controversial. Even very high doses of radiation cannot control tumor growth. It remains unclear whether radiation therapy may palliate tumor associated symptoms. Prophylactic radiation of puncture channels and thoracotomy scars is effective to prevent tumor growth caused by seeding of mesothelioma cells.

Research of the biological behavior of mesothelioma resulted in first phase I gene therapy trials. The results of the few promising approaches tested in phase II and III trials with sufficient patient numbers have to be awaited until we have learned whether and in which stage of the disease patients may benefit from therapy.