ASTRO 2015: Patients With Intermediate-Risk Meningiomas Who Receive Postoperative Radiotherapy Have a 96% 3-Year Progression-Free Survival
Patients with intermediate meningiomas treated with radiation therapy after surgery experienced a 96% 3-year progression-free survival rate and had minimal adverse events, according to research presented by Rogers et al October 21, 2015, at the American Society for Radiation Oncology’s (ASTRO’s) 57th Annual Meeting in San Antonio, Texas.
Most meningiomas, approximately 75%, are benign, and may not require immediate treatment. However, many need to be removed because of proximity to or impingement of critical structures, tumor growth, or because they are atypical or anaplastic. Treatment decisions for patients with meningioma depend on many factors, with the more advanced meningiomas often requiring a combination of surgery and radiation therapy.
Study Details
Radiation Therapy Oncology Group (RTOG) 0539, the first successfully completed cooperative group meningioma trial, enrolled 244 patients from sites throughout the United States and Canada. The study’s aim was to estimate patients’ 3-year progression-free survival rates in each of the study’s assigned patient groups. The pathology and imaging reports of patients in the trial were all centrally reviewed, and patients were assigned to three different groups depending on prognosis and management strategies, which were based upon tumor grade, recurrence status of the tumors, and the extent of the surgical removal.
In this first analysis of RTOG 0539, researchers looked at the 3-year progression-free survival and adverse events for the intermediate-risk group of patients (defined as group 2). Patients in group 2 had either a newly diagnosed, atypical, grade II meningioma with gross total resection (Simpson I–III) or a recurrent grade I (benign) meningioma, meaning that it had been previously treated with surgery, but had subsequently progressed. Any degree of surgical resection was permitted for patients with a recurrent grade I tumor. The phase II study compared the patients to a predefined historical control group of intermediate-risk meningiomas.
Of the 56 original patients classified to group 2, 52 patients received protocol treatment (three were ineligible, and one did not receive radiation therapy). Of these 52 patients, 36 (69.2%) were classified as having World Health Organization (WHO) grade II tumors with gross total resection, whereas 16 patients (30.8%) had recurrent grade I tumors.
The patients received radiation therapy of 54 Gy in 30 fractions postsurgically. While three-dimensional conformal radiation therapy was permitted within the study guidelines, the majority of patients (84.6%) received intensity-modulated radiation therapy. This was the first RTOG brain trial with protocol-specific intensity-modulated radiation therapy parameters. Four of the 52 patients withdrew (without recurrence), so 48 patients were evaluable for the primary endpoint of 3-year progression-free survival.
Study Findings
Data indicated that there was no difference in progression-free survival between the subgroups (P = .503), validating the study’s cogrouping of the patients into one prognostic category. The 3-year progression-free survival for group 2 was 96%. One patient with a WHO grade II tumor died from the disease, and one patient with a WHO grade I tumor died from an undetermined cause without disease progression.
Adverse events were scored using National Cancer Institute (NCI) common toxicity criteria, and the study specifically measured grades I or II adverse events. Among the 44 patients who received intensity-modulated radiation therapy, four patients (9%) developed grade II acute adverse events, and 11 patients (25%) had grade II late adverse events.
“Our results have been the impetus for phase III trials and support the use of postoperative radiation for intermediate-risk meningiomas, in addition to documenting positive outcomes of using intensity-modulated radiation therapy,” said Leland Rogers, MD, Professor in the Radiation Oncology Department at Virginia Commonwealth University. “We are gaining knowledge about meningiomas at a more rapid pace. This study has shown we can successfully treat meningioma patients in a large, cooperative group setting and can achieve excellent outcomes with surgery and radiation therapy.”
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