Gamma Knife radiosurgery for intracranial meningiomas: Do we need to treat the dural tail? A single-center retrospective analysis and an overview of the literature

Abstract

Background:The dural tail (DT) has been described as a common feature in meningiomas. There is a great variation of tumor invasion and extent of tumor cells in the DT. Therefore, the necessity to include the whole DT in Gamma Knife radiosurgery is not clear, since inclusion increases the target volume and therefore increases the risk of complications. In this analysis, we evaluated whether the complete tail should be included as part of the target in Gamma Knife radiosurgery for meningiomas.Methods:Between June 2002 and December 2010, Gamma Knife radiosurgery was performed in 160 patients with 203 meningiomas with a DT. In 105 tumors, the diagnosis was based on magnetic resonance imaging (MRI) characteristics, and in 98 tumors, the diagnosis was confirmed by histopathologic examination after surgery. The median volume of the tumors was 3.55 cc. All tumors were treated with Gamma Knife radiosurgery with a median prescribed dose of 13 Gy (range 11-15), resulting in a median marginal dose of 11 Gy (range 10-15). Only the part of the DT closely related to the tumor mass was included in the target. The median follow-up period was 41 months (range 12-123).Results:In image-based meningiomas, the overall local control rate was 96.2% with 2- and 5-year control rates of 98.0% and 95.1%, respectively. In WHO grade I tumors, the overall local control rate was 85.9% with 2- and 5-year control rates of 94.5% and 88.0%, respectively. The overall local control rate in World Health Organization (WHO) grade II tumors was 70.6% with control rates of 83.4% and 64.4% after 2 and 5 years, respectively. The growth of all new tumors was found in the radiation target area. No tumor growth was observed in the part of the DT that had been excluded from the target volume.Conclusion:We found in this study that routinely excluding the DT from the target does not lead to out-of-field tumor progression. Given the possibility that the DT is infiltrated with tumor cells, regular follow-up is needed.

Canine meningiomas treated with three‐dimensional conformal radiation therapy require magnetic resonance imaging to avoid a geographic miss

“…In other series, pathologic evaluation of 80 dural tails revealed neoplastic involvement was present in 50% of patients, while only congestion and inflammation was described in the other 50% . Considering that postirradiation local control rates in people are excellent even when only the dural tail adjacent to the tumor is included in the gross tumor volume, some authors raised the hypothesis that the low dose of radiation received by the dural tail may be sufficient to provide tumor control . Regardless, the exclusion of the dural tail is an important limitation of our study and implies that our suggested volume expansion might be inadequate to ensure coverage of all the neoplastic tissue.…”

“…In our study, we decided to exclude the dural tail from the gross tumor volume‐MRI contouring mainly to avoid a systematic increase in the gross tumor volume‐MRI with respect to the gross tumor volume‐CT. The inclusion of the dural tail in the gross tumor volume is still controversial in human medicine because it clinical significance remains unclear and its routine inclusion will lead to larger treatment volumes increasing the complication rate . The largest study of 179 patients with resected dural tails found that almost 90% contained neoplastic cells, of which 95% lay within 2.5 cm from the tumor base .…”

Grade II meningiomas and Gamma Knife radiosurgery: analysis of success and failure to improve treatment paradigm

“…However, marginal relapses at the border of a previously treated lesion are a common occurrence for this group of tumors. 1,4,5,10,19 Focused treatments, such as surgery and GKRS, can temporarily control new le-sions, but their high incidence and tendency to invade and progress along the dural structures will eventually prohibit long-term control of the disease. 2 Some authors choose to study relapses according to surgical bed, whereas others focus on the pattern of relapses according to the radiosurgical field.…”

“…4,19 While distal relapses are part of the natural history of the disease, local and marginal failures might be related to technical issues, such as choice of dose and target. 5,23 Although patterns of relapse have been described in several studies, few have focused on the parameters specific to marginal relapses. 5 The ability of meningiomas to become more aggressive during the course of the disease has already been established.…”

“…5,23 Although patterns of relapse have been described in several studies, few have focused on the parameters specific to marginal relapses. 5 The ability of meningiomas to become more aggressive during the course of the disease has already been established. 15,18 Better knowledge about the behavior of these tumors, including their growth patterns and growth rate, should help clinicians to more accurately assess their malignancy and, therefore, to better design an optimized dosimetric plan.…”