Controversies in radiotherapy for meningioma

Gamma Knife Radiosurgery for Atypical and Anaplastic Meningiomas

BACKGROUND

Atypical and anaplastic meningiomas have much higher recurrence rates after surgical resection compared with benign meningiomas, but the role of adjuvant radiosurgery remains unclear. This study was undertaken to evaluate the outcomes of gamma knife radiosurgery for patients with atypical and anaplastic meningiomas.

METHODS

In this retrospective analysis of a prospectively maintained database, 46 patients with histologically proven atypical or anaplastic meningiomas by current World Health Organization (WHO) criteria underwent postoperative Gamma Knife radiosurgery between 1993 and 2013. The median follow-up period was 32.6 months. The median tumor volume and margin dose were 11.7 mL (range, 2-53 mL) and 13.1 Gy (range, 12.0-16.5 Gy), respectively.

RESULTS

Local control at 3 and 5 years was 50.6% and 32.1%, respectively. Gender (P = 0.013) and marginal dose less than or equal to 13 Gy (P = 0.049) were associated with the local control. The 3- and 5-year overall survival for patients with WHO grade II was 97.1% and 88.3%, respectively, compared with 66.7% and 66.7% for patients with WHO grade III meningiomas. Radiation therapy before Gamma Knife radiosurgery (GKRS; P = 0.018) and tumor grade (P = 0.019) were the factors associated with a worse overall survival rate. Fourteen patients (30.4%) developed adverse radiation effects after GKRS treatment, and all were Radiation Therapy Oncology Group grade I.

CONCLUSIONS

Postoperative GKRS treatment for patients with atypical and anaplastic meningioma is challenging. More aggressive treatment, including of safely maximizing the extent of surgical resection and using a higher margin dose (>13Gy), should be applied to achieve better local control.

Fractionated radiotherapy and radiosurgery of intracranial meningiomas

This review focuses on the role of radiosurgery and fractionated radiotherapy in the management of intracranial meningiomas, which are the most common benign intracranial tumors. Whenever feasible, surgery remains a cornerstone of treatment in effective health care treatment where modern radiotherapy plays an important role. Irradiation can be proposed as first-line treatment, as adjuvant treatment, or as a second-line treatment after recurrence. Stereotactic radiosurgery consists of delivering, a high-dose of radiation with high precision, to the tumor in a single-fraction with a minimal exposure of surrounding healthy tissue. Stereotactic radiosurgery, especially with the gamma knife technique, has reached a high level of success for the treatment of intracranial meningiomas with excellent local control and low morbidity. However, stereotactic radiosurgery is limited by tumor size,<3-4cm, and location, i.e. reasonable distance from the organs at risk. Fractionated radiation therapy is an interesting alternative (5 to 6weeks treatment time) for large inoperable tumors. The results of fractionated radiation therapy seem encouraging as regards both local control and morbidity although long-term prospective studies are still needed.

Endoscopic Endonasal Approach to Ventral Posterior Fossa Meningiomas: From Case Selection to Surgical Management

Clival, petroclival, and foramen magnum meningiomas are challenging lesions to manage independently of the selected surgical approach. The expanded endoscopic endonasal approach (EEA) provided a safe alternative on the armamentarium of skull base approaches. There is a paucity of literature regarding endoscopic management of meningiomas because of certain limiting factors, including rarity of the pathologic condition, technical challenges, expertise of the surgical team, and available resources. The surgical technique, possible complications, and postoperative care are described in detail. This article highlights the important aspects in choosing this surgical approach and managing ventral posterior fossa meningiomas through the EEA.

Meningioma of the skull base: long-term outcome after image-guided stereotactic radiotherapy

PURPOSE

The purpose of this study was to analyse the feasibility, safety, and long-term efficacy of linear accelerator-based fractionated stereotactic radiotherapy for meningiomas of the skull base. We evaluated the long-term clinical outcome of patients and identified prognostic factors after fractionated stereotactic radiotherapy.

PATIENTS AND METHODS

Between 10/1995 and 03/2009, 136 patients with a median age of 57 years with skull base meningioma received fractionated stereotactic radiotherapy. A total of 34 patients had a grade I meningioma, in 102 cases no histology was obtained (grade 0). Fractionated stereotactic radiotherapy was delivered as primary treatment for 57 patients and postoperatively for 79. The patients received a mean total dose of 56.95 (min/max 32.4/63)Gy.

RESULTS

Median follow-up was 44.9 months. Overall progression-free survival was 96.9% after 3 years, 93.8% after 5 years, and 91.5% after 10 years. Patients with unknown histology showed progression-free survival rates of 100%, 98.7%, and 93.5% at 3, 5, and 10 years and patients with biopsy-proven grade I meningioma showed rates of 100% after 3 years, 91.7% after 5 years and 85.9% after 10 years. Patients with adjuvant radiotherapy showed significantly worse progression-free survival rates than patients who had been treated with primary radiotherapy (P=0.043), progression-free survival rates were independent of tumour size. The most common acute grade I symptoms were headache, fatigue, and local alopecia. The most common chronic grade I symptoms were fatigue and headache.

CONCLUSIONS

This large study showed that fractionated stereotactic radiotherapy is an effective and safe treatment modality with high progression-free survival rates for intracranial meningioma. We identified "prior surgery" as significant poor prognostic factor.

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

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.

Imaging of brain tumors

Neuroimaging plays a crucial role in diagnosis of brain tumors and in the decision-making process for therapy. Functional imaging techniques can reflect cellular density (diffusion imaging), capillary density (perfusion techniques), and tissue biochemistry (magnetic resonance [MR] spectroscopy). In addition, cortical activation imaging (functional MR imaging) can identify various loci of eloquent cerebral cortical function. Combining these new tools can increase diagnostic specificity and confidence. Familiarity with conventional and advanced imaging findings facilitates accurate diagnosis, differentiation from other processes, and optimal patient treatment. This article is a practical synopsis of pathologic, clinical, and imaging spectra of most common brain tumors.

Adjuvant radiotherapy for atypical and malignant meningiomas: a systematic review

Atypical meningiomas (AMs) and malignant meningiomas (MMs) are tumors with a lower incidence and poorer prognosis than benign meningiomas. The role of radiotherapy as an adjuvant to surgical resection, especially for AMs, is incompletely defined. In this study, the English-language literature was systematically reviewed for studies that reported tumor characteristics, treatment parameters, and clinical outcomes after adjuvant radiotherapy for AM and MM, including overall survival, progression-free survival, and/or time to recurrence or mortality. Clinical outcomes were further assessed in the context of resection status, timing of administration, and radiation dose. Outcomes after stereotactic radiosurgery were also examined. Treatment toxicity and other potential prognostic or confounding factors were appraised. Ten and 11 studies for AM and MM, respectively, met the inclusion criteria. The median 5-year progression-free survival and overall survival after adjuvant radiotherapy were 54.2% and 67.5%, respectively, for AM and 48% and 55.6% for MM. The complication rates were 11.1% for AM and 5.1% for MM. Incomplete resection and radiation dose <50 Gy conferred significantly poorer 5-year progression-free survival. Most studies were unable to demonstrate a statistically significant prognostic benefit for adjuvant radiotherapy in AM. In conclusion, adjuvant radiotherapy significantly improved local control of AMs and MMs, especially after subtotal resection. Study limitations, including inadequate statistical power, may underlie the studies' inability to demonstrate a statistically significant benefit for adjuvant radiotherapy in AM. Because these tumors preferentially recur within 5 years of surgical resection, future studies should define whether early adjuvant therapy should become part of the standard treatment paradigm for completely excised tumors.