Conventional Radiation Therapy for Skull Base Meningiomas

External beam radiation therapy for meningioma

Radiation therapy (RT) plays an important role in the management of meningioma. Surgery often remains the initial treatment of choice as it reduces mass effect and confirms the diagnosis and grade. However, RT has frequently been successful in the primary setting and is commonly employed as adjuvant therapy for incompletely resected tumors as well as for high-grade meningiomas regardless of resection extent. Some meningiomas develop in locations less amenable to resection or in patients who are poor surgical candidates, in which circumstances RT is particularly appropriate as primary treatment. Recent cooperative group studies including RTOG 0539 have better established the role of RT for meningioma. These studies suggest a role for adjuvant RT for completely resected Grade II meningioma, which was less clear historically. Ongoing clinical trials such as NRG BN 003 and ROAM will further clarify this. This chapter reviews the role of fractionated external beam RT for various grades of meningioma.

Gamma Knife radiosurgery for posterior fossa meningiomas: a multicenter study

OBJECT

Posterior fossa meningiomas represent a common yet challenging clinical entity. They are often associated with neurovascular structures and adjacent to the brainstem. Resection can be undertaken for posterior fossa meningiomas, but residual or recurrent tumor is frequent. Stereotactic radiosurgery (SRS) has been used to treat meningiomas, and this study evaluates the outcome of this approach for those located in the posterior fossa.

METHODS

At 7 medical centers participating in the North American Gamma Knife Consortium, 675 patients undergoing SRS for a posterior fossa meningioma were identified, and clinical and radiological data were obtained for these cases. Females outnumbered males at a ratio of 3.8 to 1, and the median patient age was 57.6 years (range 12-89 years). Prior resection was performed in 43.3% of the patient sample. The mean tumor volume was 6.5 cm(3), and a median margin dose of 13.6 Gy (range 8-40 Gy) was delivered to the tumor.

RESULTS

At a mean follow-up of 60.1 months, tumor control was achieved in 91.2% of cases. Actuarial tumor control was 95%, 92%, and 81% at 3, 5, and 10 years after radiosurgery. Factors predictive of tumor progression included age greater than 65 years (hazard ratio [HR] 2.36, 95% CI 1.30-4.29, p = 0.005), prior history of radiotherapy (HR 5.19, 95% CI 1.69-15.94, p = 0.004), and increasing tumor volume (HR 1.05, 95% CI 1.01-1.08, p = 0.005). Clinical stability or improvement was achieved in 92.3% of patients. Increasing tumor volume (odds ratio [OR] 1.06, 95% CI 1.01-1.10, p = 0.009) and clival, petrous, or cerebellopontine angle location as compared with petroclival, tentorial, and foramen magnum location (OR 1.95, 95% CI 1.05-3.65, p = 0.036) were predictive of neurological decline after radiosurgery. After radiosurgery, ventriculoperitoneal shunt placement, resection, and radiation therapy were performed in 1.6%, 3.6%, and 1.5%, respectively.

CONCLUSIONS

Stereotactic radiosurgery affords a high rate of tumor control and neurological preservation for patients with posterior fossa meningiomas. Those with a smaller tumor volume and no prior radiation therapy were more likely to have a favorable response after radiosurgery. Rarely, additional procedures may be required for hydrocephalus or tumor progression.

Controversies in radiotherapy for meningioma

Meningiomas are the most common primary intracranial tumour. Although external beam radiotherapy and radiosurgery are well-established treatments, affording local control rates of 85-95% at 10 years, the evidence base is mainly limited to single institution case series. This has resulted in inconsistent practices. It is generally agreed that radiotherapy is an established primary therapy in patients requiring treatment for surgically inaccessible disease and postoperatively for grade 3 tumours. Controversy exists surrounding whether radiotherapy should be upfront or reserved for progression for incompletely excised and grade 2 tumours. External beam radiotherapy and radiosurgery have not been directly compared, but seem to offer comparable rates of control for benign disease. Target volume definition remains contentious, including the inclusion of hyperostotic bone, dural tail and surrounding brain, but pathological studies are shedding some light. Most agree that doses around 50-54 Gy are appropriate for benign meningiomas and ongoing European Organization for Research and Treatment of Cancer and Radiation Therapy Oncology Group studies are evaluating dose escalation for higher risk disease. Here we address the 'who, when and how' of radiotherapy for meningioma.

Stereotactic radiosurgery and radiotherapy in benign intracranial meningioma

PURPOSE

To investigate the role of stereotactic radio surgery (SRS) and hypo-fractionated stereotactic radiotherapy (SRT) in treatment of benign intracranial meningioma.

PATIENTS AND METHODS

Between 2003 and 2010, 32 patients with a median age of 44 years (range 21-67 years) were treated with SRS (n=19), and hypo-fractionated SRT (n=13) for intracranial meningioma. Fourteen patients underwent SRS or SRT as their primary treatment, while 18 patients underwent post operative SRS or SRT (PORT). Cumulative progression free survival, overall cumulative survival, toxicity and symptomatology were evaluated.

RESULTS

The median follow up period was 39 months (range 6-72 months). The 5 year overall survival and progression free survival were 90 ± 5% and 94 ± 4% after SRT or SRS respectively. Symptoms were improved or stable in 94% of patients. Acute toxicity was mild, and was seen in 41% of patients. Clinically significant late morbidity or new cranial nerve palsies did not occur.

CONCLUSION

Stereotactic radio surgery (SRS) and hypo-fractionated stereotactic radiotherapy (SRT) are effective and safe treatment modality for local control of meningioma with low risk of significant late toxicity. In case of large tumor size and adjacent critical structures, hypo-fractionated SRT is highly recommended.

Gamma Knife surgery of meningiomas located in the posterior fossa: factors predictive of outcome and remission

Object

Although numerous studies have analyzed the role of stereotactic radiosurgery for intracranial meningiomas, few studies have assessed outcomes of posterior fossa meningiomas after stereotactic radiosurgery. In this study, the authors evaluate the outcomes of posterior fossa meningiomas treated with Gamma Knife surgery (GKS). The authors also assess factors predictive of new postoperative neurological deficits and tumor progression.

Methods

A retrospective review was performed of a prospectively compiled database documenting the outcomes of 152 patients with posterior fossa meningiomas treated at the University of Virginia from 1990 to 2006. All patients had a minimum follow-up of 24 months. There were 30 males and 122 females, with a median age of 58 years (range 12–82 years). Seventy-five patients were treated with radiosurgery initially, and 77 patients were treated with GKS after resection. Patients were assessed clinically and radiographically at routine intervals following GKS. Factors predictive of new neurological deficit following GKS were assessed via univariate and multivariate analysis, and Kaplan-Meier analysis and Cox multivariate regression analysis were used to assess factors predictive of tumor progression.

Results

Patients had meningiomas centered over the tentorium (35 patients, 23%), cerebellopontine angle (43 patients, 28%), petroclival region (28 patients, 18%), petrous region (6 patients, 4%), and clivus (40 patients, 26%). The median follow-up was 7 years (range 2–16 years). The mean preradiosurgical tumor volume was 5.7 cm3 (range 0.3–33 cm3), and mean postradiosurgical tumor volume was 4.9 cm3 (range 0.1–33 cm3). At last follow-up, 55 patients (36%) displayed no change in tumor volume, 78 (51%) displayed a decrease in volume, and 19 (13%) displayed an increase in volume. Kaplan-Meier analysis demonstrated radiographic progression-free survival at 3, 5, and 10 years to be 98%, 96%, and 78%, respectively. In Cox multivariable analysis, pre-GKS covariates associated with tumor progression included age greater than 65 years (hazard ratio [HR] 3.24, 95% CI 1.12–9.37; p = 0.03) and a low dose to the tumor margin (HR 0.76, 95% CI 0.60–0.97; p = 0.03), and post-GKS covariates included shunt-dependent hydrocephalus (HR 25.0, 95% CI 3.72–100.0; p = 0.001). At last clinical follow-up, 139 patients (91%) demonstrated no change or improvement in their neurological condition, and 13 patients showed symptom deterioration (9%). In multivariate analysis, the only factors predictive of new or worsening symptoms were clival or petrous location (OR 4.0, 95% CI 1.1–13.7; p = 0.03).

Conclusions

Gamma Knife surgery offers an acceptable rate of tumor control for posterior fossa meningiomas and accomplishes this with a low incidence of neurological deficits. In patients selected for GKS, tumor progression is associated with age greater than 65 years and decreasing dose to the tumor margin. Clival- or petrous-based locations are predictive of an increased risk of new or worsening neurological deficit following GKS.

Fractionated conformal radiotherapy in the management of cavernous sinus meningiomas: long-term functional outcome and tumor control at a single institution

PURPOSE

To evaluate long-term outcome of cavernous sinus meningioma (CSM) treated with fractionated conformal radiotherapy (FCR).

PATIENTS AND METHODS

Fifty-three patients with CSMs (16 men [30.2%], 37 women [69.8%], aged 53 ± 13.0 years [mean ± SD]) were treated by FCR. In 28 patients (52.8%) FCR was performed as first-line treatment and in 25 patients (47.2%) as adjuvant treatment. All patients received FCR with a dose of 52.9 ± 1.8 Gy in 29.4 ± 1.0 fractions over 6 weeks. Dose per fraction was 1.9 ± 0.1 Gy. Radiotherapy was delivered stereotactically in 47 cases (88.7%) and conformally in 6 (11.3%)

RESULTS

The median follow-up was 6.9 years (range, 3-19 years). According to Sekhar's classification, 19 patients (35.8%) were Grade 1-2, 30 patients (56.6%) were Grade 3-4, and 4 patients (7.6%) were Grade 5. Pretreatment tumor volume was determined in 46 patients, and tumor volume was 12.6 ± 8.2 cm(3). In these patients, the distance between tumor and optic apparatus was 1.62 ± 1.2 mm. Actuarial 5- and 10-year progression-free survival rates were 98.1% and 95.8%, respectively. Clinical improvement was observed in 31 patients (58.5%), and 20 patients (37.7%) remained unchanged. Radiologic response was observed in 18 patients (30.2%), and 35 patients (66.0%) showed stable lesions. Two patients (3.8%) showed tumor progression during follow-up. Transient morbidity was observed in 3 patients (5.7%) and permanent morbidity in 1 (1.9%).

CONCLUSION

Fractionated conformal radiotherapy affords satisfactory long-term tumor control and low treatment morbidity.

Chronic suppressive therapy with calcium channel antagonists for refractory meningiomas

✓In this article, the authors review the research supporting the use of calcium channel antagonists (CCAs) in the treatment of recurrent or unresectable meningiomas. Calcium channel antagonists (for example, diltiazem and verapamil) are known to augment the effects of chemotherapy drugs (for example, vincristine) in multiple cancers. Although it was initially thought that this occurred by interference with calcium-dependent secondary messenger systems, it appears that other mechanisms account for this effect. The authors' initial work in this field was based on the then-emerging data that meningiomas are receptor positive for growth factor receptors (for example, platelet-derived growth factor [PDGF]), which are known to trigger calcium-dependent secondary messenger pathways. In fact, they were able to show that CCAs block the growth stimulatory effects of multiple growth factors, including PDGF, in vitro and augment the growth inhibitory effects of hydroxyurea and RU486 (mifepristone). The authors have shown similar in vivo growth inhibition by these agents. In addition, diltiazem- and verapamil-treated meningiomas are less vascular and smaller, with decreased cell proliferation and increased apoptosis. The use of CCAs is attractive as an adjunct treatment for unresectable or recurrent meningiomas because they are safe drugs with well-known side effect profiles that lend themselves to long-term chronic therapy.

Calcium Channel Antagonists Augment Hydroxyurea- And Ru486-Induced Inhibition Of Meningioma Growth In Vivo And In Vitro

OBJECTIVE

Although the chemotherapy drug hydroxyurea (HU) and the antiprogesterone mifepristone (RU486) have been used to treat meningiomas for which surgical and radiation therapies have failed, results have been disappointing. The addition of calcium channel antagonists (CCAs) to chemotherapeutic drugs enhances tumor growth inhibition in other tumor types, and the authors demonstrated that CCAs can block meningioma growth in vitro and in vivo. The purpose of this study was to test the effects of the addition of a CCA to HU or RU486 on meningioma growth.

METHODS

Primary and malignant (IOMM-Lee) meningioma cell lines were treated with HU, RU486, or either of these plus diltiazem or verapamil. Assays for cell growth, apoptosis, and fluorescent-activated cell sorting were performed on in vitro cultures. Similar cell lines were implanted into nude mice and were treated with HU or RU486, in combination with a CCA. Tumors were analyzed by light microscopy, MIB-1, and factor VIII immunohistochemical staining studies.

RESULTS

The addition of diltiazem or verapamil to HU or RU486 augmented meningioma growth inhibition by 20 to 60% in vitro. In vivo, tumors treated with combination drugs were smaller; and immunohistochemical analysis of the IOMM-Lee tumors showed a 10% decrease in the MIB-1 ratio (from 0.41 to 0.30) and an approximate 75% decrease in microvascular density.

CONCLUSION

The addition of diltiazem or verapamil to HU or RU486 augments meningioma growth inhibition in vitro by inducing apoptosis and G1 cell-cycle arrest. The combination of HU and diltiazem inhibited the growth of meningiomas in vivo by decreasing proliferation and microvascular density. These results suggest a possible role for these drugs as an additional adjuvant therapy for recurrent or unresectable meningiomas.

Evaluation of fractionated radiotherapy and gamma knife radiosurgery in cavernous sinus meningiomas: treatment strategy

OBJECTIVE

To investigate the respective role of fractionated radiotherapy (FR) and gamma knife stereotactic (GKS) radiosurgery in cavernous sinus meningioma (CSM) treatment.

METHODS

The authors report the long-term follow-up of two populations of patients harboring CSMs treated either by FR (Group I, 38 patients) or GKS radiosurgery (Group II, 36 patients). There were 31 females with a mean age of 53 years in Group I and 29 females with a mean age of 51.2 years in Group II. In 20 patients (Group I) and 13 patients (Group II), FR and GKS radiosurgery were performed as an adjuvant treatment. In 18 patients (Group I) and in 23 patients (Group II), FR and GKS radiosurgery were performed as first line treatment. In our early experience with GKS radiosurgery (1992, date of gamma knife availability in the department), patients with tumors greater than 3 cm, showing close relationship with the optic apparatus (<3 mm) or skull base dural spreading, were treated by FR. Secondarily, with the advent of new devices and our growing experience, these criteria have evolved.

RESULTS

The median follow-up period was 88.6 months (range, 42-168 mo) for Group I and 63.6 months (range, 48-92 mo) for Group II. According to Sekhar's classification, 26 (68.4%) patients were Grade III to IV in Group I and 10 (27.8%) patients in Group II (P < 0.05); 23 (60.5%) patients had extensive lesions in Group I and 7 (19.4%) patients in Group II (P < 0.05). Mean tumor volume was 13.5 cm in Group I and 5.2 cm in Group II (P < 0.05). Actuarial progression-free survival was 94.7% and 94.4% in Group I and II, respectively. Clinically, improvement was seen for 24 (63.2%) patients in Group I and for 21 (53.8%) patients in Group II (P > 0.05). Radiologically, 11 (29%, Group I) patients and 19 (Group II, 52.7%) patients showed tumor shrinkage (P = 0.04). Transient morbidity was 10.5% in Group I and 2.8% in Group II. Permanent morbidity was 2.6% in Group I and 0% in Group II.

CONCLUSION

FR and GKS radiosurgery are safe and efficient techniques in treatment of CSMs, affording comparable satisfactory long-term tumor control. However, GKS radiosurgery provides better radiological response, is far more convenient, and fits into most patients lives much better than FR. Therefore, in the authors' opinion, GKS radiosurgery should be advocated in first intention for patients with CSMs, whereas conventional radiotherapy should be reserved for cases that are not amenable to this technique, thus making these two therapeutic modalities not alternative but complementary tools in CS meningioma treatment strategy.

[Role of radiotherapy in the treatment of cerebral meningiomas]

Cerebral meningiomas account for 15-20% of all cerebral tumours. Although seldom malignant, they frequently recur in spite of complete surgery, which remains the cornerstone of the treatment. In order to decrease the probability of local recurrence, radiotherapy has often been recommended in atypical or malignant meningioma as well as in benign meningioma which was incompletely resected. However, this treatment never was the subject of prospective studies, randomized or not. The purpose of this review of the literature was to give a progress report on the results of different published series in the field of methodology as well as in the techniques of radiotherapy. Proposals for a therapeutic choice are made according to this analysis. For grade I or grade II-III meningiomas, limits of gross tumor volume (GTV) include the tumour in place or the residual tumour after surgery; clinical target volume (CTV) limits include gross tumour volume before surgery with a GTV-CTV distance of 1 and 2 cm respectively. Delivered doses are 55 Gy into CTV and 55-60 Gy and 70 Gy into GTV for grade I and grade II-III meningiomas respectively.