Mesothelioma IMRT More Effective Than Conventional Radiation

Intensity Modulated Radiotherapy (IMRT) appears to be the most effective and safest type of radiotherapy for treating mesothelioma patients after surgery. A new study published in the Journal of Thoracic Oncology says IMRT has advantages over conventional radiotherapy when used as part of a multi-modality approach to combat mesothelioma. Malignant mesothelioma, the asbestos-linked cancer, can take 20 to 40 years to develop but once it does, it often grows quickly. No single therapy has been shown to be universally effective at combating mesothelioma. A growing body of scientific evidence suggests that the most effective approach involves removing as many cancer cells as possible through a radical surgery called extrapleural pneumonectomy, and following the surgery with a combination of chemotherapy and radiotherapy. But, as the study’s authors point out, even this approach has its drawbacks.

“Local control remains poor despite the inclusion of conventional adjuvant radiation therapy in trimodality therapy,” they write. “This can be improved by the delivery of adjuvant IMRT.”

Using a systematic review of relevant studies from around the world, the team of University of Arizona researchers evaluated the outcomes of mesothelioma cases that used radiotherapy as part of the treatment. One of the problems with conventional radiotherapy for mesothelioma is that mesothelioma tumors tend to be irregular in shape, span a large area, and are located adjacent to sensitive structures like the lungs or heart. The researchers found that IMRT, a form of radiotherapy which modulates or changes the intensity of the radiation to match the tumor’s shape, tends to achieve better ‘local control’ of the tumor than conventional radiotherapy.

But IMRT is not without its drawbacks for mesothelioma patients. Unless it is administered very carefully by an experienced team skilled at keeping radiation dose levels low, IMRT can cause serious damage to the remaining lung. The authors note that this is especially true for patients who are receiving chemotherapy. They point out that new, lower-dose IMRT technology allows for decreased delivery time and safer coverage of the target area when used by an experienced team.

The article concludes, “Excellent local control can be achieved through adjuvant IMRT after EPP for malignant pleural mesothelioma. Severe pulmonary toxicity may be avoided by setting stringent dose constraints for the contralateral lung. This can be aided by the advances in technology.”

They suggest that PET scanning be used for reliable post-treatment evaluation.

Sources:

Chi, A et al, “Intensity-Modulated Radiotherapy after Extrapleural Pneumonectomy in the Combine-Modality Treatment of Malignant Pleural Mesothelioma”, April 28, 2011, The Journal of Thoracic Oncology, Epub ahead of print. Baldin, EH, “Radiation Therapy Options for Malignant Pleural Mesothelioma”, Summer, 2009, Seminars in Thoracic and cardiovascular Surgery, pp. 159-63.