New radiotherapy technique may help post-op mesothelioma patients
A new radiation technique may improve outcomes for pleural mesothelioma patients who have undergone surgery.
Intensity-modulated radiation therapy, or IMRT, is a standard post-operative treatment for patients who have undergone extrapleural pneumonectomy, a surgery that removes the mesothelioma tumor and lining of the lung where the tumor is located. While higher radiation doses can improve outcomes, they also increase the risk of pneumonitis, a potentially fatal inflammation of the lungs. Higher doses can also prove more toxic to patients receiving chemotherapy.
Physicians have found it difficult to give adequate radiation doses to pleural mesothelioma patients because of the irregular shape of the post-operative area targeted for treatment. IMRT also poses a risk of damaging the tissue of critical organs such as the spinal cord, kidneys, liver and heart.
But a limited study by Japanese doctors suggests that helical tomotherapy, in which radiation is aimed at a tumor from different directions, could help mesothelioma patients.
Helical tomotherapy is a type of IMRT in which the radiation source rotates around a patient moving through a donut-shaped machine. A 3-D image of the tumor is taken before radiation, helping doctors determine the highest dose of radiation needed to kill tumor cells while limiting damage to nearby tissue.
The Japanese study involved three male patients prescribed escalating doses of radiation to cover an estimated 95 percent of the target area. All of the patients had received chemotherapy with cisplatin before surgery; one patient had suffered a reoccurrence of disease. Physicians followed up at 9, 14 and 26 months. All three patients were still alive, and none had developed pneumonitis. In all three cases, the radiation’s “dose-volume” on nearby organs was considered normal.
The researchers acknowledged the limitations of a study involving only three cases and urged further investigations with a larger number of patients and longer follow-up. However, they said the findings suggest using IMRT with helical tomotherapy has relatively minor adverse effects compared to conventional radiotherapy. Overall, they said, the technique “has the potential to conform radiation doses tightly to irregularly shaped targets and might be better able to spare adjacent normal tissue compared with conventional approaches.”
The study, the first to report on post-operative mesothelioma patients treated by IMRT using helical tomotherapy, will be published in an upcoming issue of the Journal of Radiation Research.