There are no randomized clinical trials available to prove the efficiency of radiation therapy in malignant mesothelioma and the role of radiation therapy in the curative treatment of the disease remains unclear. However several studies have suggested beneficial effect with use of radiation therapy in malignant mesothelioma. Mesothelioma cell lines demonstrate a high level of sensitivity to radiation in the laboratory, however cell lines from different patients may show varying levels of sensitivity to radiation.
Since pleural mesothelioma is an extensive disease along the pleura, large areas of pleura are to be covered with the radiation treatment. This would often result in use of high doses of radiation to cover all the areas involved with mesothelioma. High doses of radiation may result in damage to the underlying lung, heart, spinal cord and liver with associated increased risk of complications. Occasionally radiation therapy may show regression of tumor and very good responses may be seen in mesothelioma, but this modality of treatment has not shown to improve survival. Radiation therapy is often used to prevent seeding of the biopsy tracts and surgical wounds.
Instillation of radioactive colloids in to the pleural cavity may be effective in controlling the pleural effusion. Radioactive gold or chromic phosphate is often used for this purpose. The exact response rates and duration of response to this approach is not clear. Some reports suggest that the response may last as long as one year or more. Treatment of the pleural surface by radio active materials mentioned will not have any significant effect on the mesothelioma as a whole and any therapeutic effect on the gross tumor would be limited.