Patients with non-metastatic malignant pleural mesothelioma may benefit from definitive radiation therapy, according to a large retrospective study recently presented at the American Society for Radiation 2016 Annual Meeting, held Sept. 25–28 in Boston.
Although the use of definitive radiation therapy was found to be very low compared to surgery or chemotherapy, the study, “Definitive Radiation Therapy Is Associated With Improved Survival in Non-Metastatic Malignant Pleural Mesothelioma,” found that radiation therapy can improve patient survival by about 23 percent.
Radiation therapy is one of the main types of treatment options for mesothelioma, after surgical resection of the tumor and chemotherapy. Currently, there are two types of radiation used to treat pleural mesothelioma: external beam radiation, which is non-invasive, and intraoperative radiation, which requires the application of radioactive beams directly into the tumor site during surgery.
In this observational, retrospective study, published in the journal Radiation Oncology, the researchers analyzed cancer registry data to assess the usage rates of definitive radiation therapy in malignant pleural mesothelioma, and whether the therapy influenced patients’ survival. Definitive radiation therapy was defined as the receipt of 40-65 Gy of external beam radiation therapy to the chest wall, lungs, or pleura.
Among the 23,414 patients with mesothelioma included in the National Cancer Data Base, 14,019 matched the inclusion criteria and were analyzed further. The researchers report a median age of 74 years in their cohort, which was mostly composed of white people (93.2%).
Nearly half of the patients in this cohort received chemotherapy, 20 percent underwent surgery to remove their tumors, and 3.6 percent received definitive radiation therapy.
But the researchers found that those who received radiation therapy had better overall survival rates than those who did not, both at two-year (33.2% vs 19.4%) and five-year follow-up (12.4% vs 5.2%). After adjusting for demographic, pathologic, and treatment factors, those who received definitive radiation therapy had a 27 percent improved survival, compared to those who did not.
They also found that surgical resection, chemotherapy, treatment at an academic facility, and higher income were all independently associated with improved survival. In addition, their results revealed that those who received both surgery and radiation had better survival rates (40% increase) than those who underwent surgery alone (25% increase), or who received radiation therapy alone (26% increase).
The study also reports decreased survival in patients who have higher co-morbidity scores (have several diseases or disorders in addition to malignant mesothelioma), Medicaid/Medicare insurance (compared to private insurance), and a non-epithelial subtype of the disease.
Researchers believe that, in the advent of improved radiation delivery techniques, their findings support the increased utilization of radiation therapy to treat patients with malignant pleural mesothelioma.