The targeted radiotherapy technique known as intensity-modulated radiotherapy (IMRT) may offer a safer way to treat pleural mesothelioma tumors with fewer side effects.
Researchers at Gazi University in Ankara, Turkey recently compared the outcomes of twenty-four radiation therapy plannings in patients with malignant pleural mesothelioma and found that IMRT was both less dangerous and more effective.
Radiotherapy for Mesothelioma
Radiotherapy is often used in pleural mesothelioma treatment as part of a multi-modal approach that typically also includes surgery and chemotherapy. In many cases, patients will receive radiotherapy after surgery in an effort to destroy residual mesothelioma cells that could potentially seed new mesothelioma tumors.
But radiotherapy for mesothelioma is a complex proposition, largely because of the shape and location of most mesothelioma tumors.
Pleural mesothelioma grows on the membrane that surrounds the lungs and lies in close contact with other vital organs. Irradiating the mesothelioma tumor while protecting both the lungs and other nearby organs is especially challenging and relies on detailed planning beforehand.
Testing IMRT for Mesothelioma
In the new Turkish study, twelve mesothelioma patients received radiation to one side of their chest in doses ranging from 1.8 Gy to 50.4 Gy. All organs at risk were figured into the treatment plan to avoid absorbing radiation unnecessarily.
Some of the mesothelioma patients were slated to have standard conformal radiotherapy which uses combined photon-electron fields.
For other patients, IMRT was planned to target the mesothelioma tumor with 7 to 9 beams of radiation pointed at it from different carefully-selected angles. In both cases, strict limits were placed on how high a dose any one area could absorb.
Results Favor IMRT
In an article in the journal Technology in Cancer Research and Treatment, the Turkish team concludes that IMRT was the better choice for their mesothelioma study subjects.
“Intensity-modulated radiation therapy was statistically superior in target coverage and dose homogeneity,” says Sukran Ulger, MD, a radiation oncologist and part of the medical faculty at Gazi University.
The study found that, with IMRT, mesothelioma tumors received a higher dose of cancer-killing radiation while the surrounding healthy lung tissue received less.
“With a complex and large target volume of malignant pleural mesothelioma, intensity-modulated radiation therapy has the ability to deliver efficient tumoricidal radiation dose within the safe dose limits of the remaining lung tissue,” concludes the report.
Recent studies conducted by researchers in Texas and New York found that mesothelioma patients who had IMRT after either EPP or P/D surgery lived longer than most people with the asbestos cancer.
IMRT is a specialized type of radiation therapy that is typically available at larger cancer centers.
Ulger, S, et al, “Intensity-Modulated Radiation Therapy Improves the Target Coverage Over 3-D Planning While Meeting Lung Tolerance Doses for All Patients With Malignant Pleural Mesothelioma”, June 2017, Technology in Cancer Research & Treatment, pp. 332-338
Jhavar, S, “Intensity modulated radiation therapy after extrapleural pneumonectomy for malignant pleural mesothelioma is feasible without fatal pulmonary toxicity and provides good survival”, Asia-Pacific Journal of Clinical Oncology, March 29, 2017, Epub ahead of print