Mesothelioma Treatment Improvements with Intensity-Modulated Radiotherapy
Mesothelioma researchers out of Denmark recently published a review of their experience with intensity-modulated radiotherapy (IMRT) and the incidence of pulmonary toxicity following this type of radiation.
The article, titled “Pulmonary toxicity following IMRT after extrapleural pneumonectomy for malignant pleural mesothelioma,” was published in the journal Radiotherapy and Oncology and discusses the potential toxic effects of IMRT and offers recommendations on how to reduce and prevent pulmonary toxicity.
“Intensity-modulated radiotherapy (IMRT) has allowed for an increase in dose to the pleural cavity and reduction in radiation doses to organs at risk. The present study reports and analyzes the incidence of fatal pulmonary toxicity in patients treated at Rigshospitalet, Copenhagen,” state the authors of the study. Rigshospitalet is the national hospital of Denmark.
The study included 26 patients with malignant mesothelioma, a cancer caused almost exclusively by asbestos exposure. All participants were treated with trimodal therapy including induction chemotherapy followed by an extrapleural pneumonectomy (EPP) and IMRT. Treatments took place between April 2003 and April 2006.
Patients were administered IMRT four to six weeks after EPP surgery. Application of IMRT was planned on results from CT scans depicting the remaining cancer. An amount of 50 Gy (“Gy” is the amount of absorbed radiation) was applied to the entire pleural surface area as well as thoracotomy scars, which can tend to develop cancerous growths. Organs at risk (OARs), including contralateral lung, spinal cord, esophagus, heart, liver and kidneys were contoured on the planning CT scan to be avoided during therapy.
Acute toxicity symptoms that were reported during radiotherapy included nausea, vomiting, esophaitis, dyspnea and thrombocytopenia. Severe late toxicity was recorded in five patients. One patient developed severe thrombocytopenia and four patients experienced severe lung toxicity (pneumonitis).
The researchers reported that “the incidence of fatal radiation-induced pneumonitis in patients with MPM [malignant pleural mesothelioma] treated with trimodality therapy has been reported to be as high as six of 13 patients (46%) in a study from 2006 by Allen et al. Subsequently, the incidence of fatal pulmonary complications was reported to be 10% in a series of 63 patients treated at The University of Texas M.D. Anderson Cancer Center with EPP and IMRT and 8% in a series of 13 patients treated at Duke University Medical Center.”
Results from these studies have suggested that low-dose radiation to the remaining normal lung tissue after surgery is the main contributor to lung toxicity. The researchers concluded, “Based on the obtained data we suggest a modification of lung dose constraints in order to avoid unacceptable lung toxicity after trimodal therapy for MPM.”
Additional information about mesothelioma and treatment options may be found through the Mesothelioma Center.
