Determining the Role of Adjuvant Radiotherapy in the Management of Meningioma

A Surveillance, Epidemiology, and End Results Analysis

Abhinav K. Reddy, MS; James S. Ryoo, BS; Steven Denyer, MS; Laura S. McGuire; Ankit I. Mehta, MD

Disclosures

Neurosurg Focus. 2019;46(6):e3 

In This Article

Abstract and Introduction

Abstract

Objective: The aim of this study was to illustrate the demographic characteristics of meningioma patients and observe the effect of adjuvant radiation therapy on survival by using the Surveillance, Epidemiology, and End Results (SEER) database. More specifically, the authors aimed to answer the question of whether adjuvant radiotherapy following resection of atypical meningioma confers a cause-specific survival benefit. Additionally, they attempted to add to previous characterizations of the epidemiology of primary meningiomas and assess the effectiveness of the standard of care for benign and anaplastic meningiomas. They also sought to characterize the efficacy of various treatment options in atypical and anaplastic meningiomas separately since nearly all other analyses have grouped these two together despite varying treatment regimens for these behavior categories.

Methods: SEER data from 1973 to 2015 were queried using appropriate ICD-O-3 codes for benign, atypical, and anaplastic meningiomas. Patient demographics, tumor characteristics, and treatment choices were analyzed. The effects of treatment were examined using a multivariate Cox proportional hazards model and Kaplan-Meier survival analysis.

Results: A total of 57,998 patients were included in the analysis of demographic, meningioma, and treatment characteristics. Among this population, cases of unspecified WHO tumor grade were excluded in the multivariate analysis, leaving a total of 12,931 patients to examine outcomes among treatment paradigms. In benign meningiomas, gross-total resection (HR 0.289, p = 0.013) imparted a significant cause-specific survival benefit over no treatment. In anaplastic meningioma cases, adjuvant radiotherapy imparted a significant survival benefit following both subtotal (HR 0.089, p = 0.018) and gross-total (HR 0.162, p = 0.002) resection as compared to gross-total resection alone. In atypical tumors, gross-total resection plus radiotherapy did not significantly change the hazard risk (HR 1.353, p = 0.628) compared to gross-total resection alone. Similarly, it was found that adjuvant radiation did not significantly benefit survival after a subtotal resection (HR 1.440, p = 0.644).

Conclusions: The results of this study demonstrate that the role of adjuvant radiotherapy, especially after the resection of atypical meningioma, remains somewhat unclear. Thus, given these results, prospective randomized clinical studies are warranted to provide clear information on the effects of adjuvant radiation in meningioma treatment.

Introduction

MENINGIOMAS are one of the most prevalent forms of tumor seen in the central nervous system (CNS), accounting for about a third of all primary brain and CNS tumors.[15] They typically arise from arachnoid cap cells in the meninges surrounding the brain and spine, can be readily diagnosed with imaging, and are often found incidentally during imaging for other medical purposes.[21] An increase in cranial imaging for a variety of medical indications has led to a greater reported incidence of primary meningioma in patients who were not originally being assessed for meningioma.[18] The majority of meningiomas are benign, slow-growing tumors (ICD-O-3 behavior 0); however, some forms are more aggressive and are categorized as either atypical (ICD-O-3 behavior 1) or anaplastic (ICD-O-3 behavior 3) meningiomas.[1]

Previous epidemiological studies have shown that benign meningiomas represent approximately 94% of all meningioma cases, whereas atypical and anaplastic meningiomas account for about 4% and 1%, respectively.[1] These tumors are most common in older individuals, with an average age of approximately 64 years at onset and an increasing incidence with age.[1] There is also a well-documented increased incidence of these tumors in women (73% in women overall[8] and 80% of spinal cord meningiomas in women[23]). Some evidence suggests that this trend is not seen in pediatric patients,[8] in whom these tumor types are rare and likely associated with neurofibromatosis type 2 (NF2) or therapeutic radiation for other malignancies.[11] Overall, death from benign meningiomas is very low with exceptions for tumors in locations such as the skull base where the risk from tumor growth is greater.[5] Atypical and anaplastic meningiomas have lower survival rates and are often associated with recurrence.[10]

Given that benign meningiomas are a slow-growing malignancy, the usual treatment course involves observation after diagnosis through imaging.[24] For most patients, the meningioma will be asymptomatic, and as long as the tumor size does not drastically increase, there is no urgency to treat surgically.[4] However, an exception to this stance relates to pediatric patients, in whom there is the concern that future surgery will be required and the decision to perform gross-total resection (GTR) early may be made.[14] For most benign meningiomas for which GTR is successfully completed, adjuvant radiotherapy is not indicated.[5] For atypical meningiomas, which have a higher rate of recurrence, standard practice is to perform GTR when possible; however, there is ongoing debate over whether adjuvant radiotherapy should be provided in cases in which GTR is successful, with studies showing various effects on survival.[2,3,19] The advent of newer, more focused radiotherapy options has added to the question of whether to radiate in these cases and whether that radiation will improve outcomes. For anaplastic meningiomas, which are highly aggressive and come with a poor prognosis, GTR and subsequent radiotherapy are both indicated.[16]

In the present study, in which we conducted the largest-to-date Surveillance, Epidemiology, and End Results (SEER) analysis of primary meningiomas, we aimed to answer the question of whether adjuvant radiotherapy following resection of atypical meningioma confers a cause-specific survival benefit. Additionally, we attempted to add to previous characterizations of the epidemiology of primary meningiomas and assess the effectiveness of the standard of care for benign and anaplastic meningiomas. We also sought to characterize the efficacy of various treatment options in atypical and anaplastic meningiomas separately since nearly all other analyses have grouped these two together despite varying treatment regimens for these behavior categories.

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