Background: Although usually associated with asbestos exposure, a number of case reports have noted the occurrence of malignant pleural mesothelioma in patients who received radiotherapy (RT) to the thorax.
Methods: The authors performed a retrospective cohort study utilizing 251,750 women registered with breast carcinoma in the Surveillance, Epidemiology, and End Results Program of the U.S. National Cancer Institute from 1973-1993, 24.8% of whom received RT as part of their initial management, and 13,743 people with Hodgkin's disease, 50.6% of whom received RT as part of their initial management.
Results: Six cases of malignant pleural mesothelioma were found: two in breast carcinoma patients treated with RT and four found in women not treated with RT. No cases occurred in the patients with Hodgkin's disease. The overall estimated relative risk for malignant pleural mesothelioma after RT was 1.56 (95% confidence interval, 0.18-5.63).
Conclusions: To the authors' knowledge, this is the first controlled study to investigate thoracic radiation exposure and malignant pleural mesothelioma, and no association was found.