Hormone treatment of meningiomas: lack of response to medroxyprogesterone acetate (MPA). A pilot study of five cases

Medical Management of Meningiomas

Meningiomas represent the most common type of benign tumor of the extra-axial compartment. Although most meningiomas are benign World Health Organization (WHO) grade 1 lesions, the increasingly prevalent of WHO grade 2 lesion and occasional grade 3 lesions show worsened recurrence rates and morbidity. Multiple medical treatments have been evaluated but show limited efficacy. We review the status of medical management in meningiomas, highlighting successes and failures of various treatment options. We also explore newer studies evaluating the use of immunotherapy in management.

Advances in the systemic therapy for recurrent meningiomas and the challenges ahead

INTRODUCTION

Meningiomas represent the most common primary neoplasms of the central nervous system (CNS). 20% present with atypical (WHO grade II) or malignant (grade III) meningiomas, which show aggressive biologic behavior and high recurrence. Although surgical resection and radiation therapy are the primary treatment options for these tumors, there is a subgroup of patients who do not respond well to or are poor candidates for these approaches, leading to the exploration of systemic therapies as an alternative.

AREAS COVERED

The literature on different therapeutic groups of systemic drugs for recurrent meningiomas is reviewed, with a focus on the different molecular targets. Past and current ongoing clinical trials are also discussed.

EXPERT OPINION

To date, there is no recognized treatment that has demonstrated a substantial increase in progression-free or overall survival rates. Nonetheless, therapies targeting anti-VEGF have exhibited more encouraging results in general. The examination of genomic and epigenomic traits of meningiomas, along with the integration of molecular markers into the latest WHO tumor grading system, has provided valuable insights. This has opened avenues for exploring numerous intracellular and extracellular pathways, as well as mutations, that have been targeted in ongoing clinical trials.

The Role of Pharmacotherapy in Treatment of Meningioma: A Systematic Review

The safety and efficacy of various pharmacotherapeutic regimens on refractory meningiomas have been the focus of investigations. We present a comprehensive review of the previous efforts and the current state of ongoing clinical trials. A PRISMA-compliant review of the MEDLINE and ClinicalTrial.gov databases of the National Library of Medicine were performed. The primary outcomes of interest for included articles were radiographic response, overall survival, progression-free survival, six-month progression-free survival, and adverse events. Overall, 34 completed trials and 27 ongoing clinical trials were eligible. Six-month progression-free survival was reported in 6-100% of patients in the completed studies. Hematological disorders were the most common adverse events. Of the ongoing clinical trials identified, nine studies are phase I clinical trials, eleven are phase II trials, two are phase I and II trials, one is phase II and III, and two trials do not have a designated phase. Currently, there is no effective chemotherapy for refractory or recurrent meningiomas. Several promising targeted agents have been developed and are currently being investigated in the hope of identifying novel therapeutic strategies for the treatment of this pathology.

Atypical acute presentation of an optic nerve sheath meningioma

PURPOSE

Primary optic nerve sheath meningiomas (ONSM) are benign lesions that typically present with findings of painless proptosis (59%), optic nerve pallor (55%), and decreased peripheral vision (35%). Herein we share an atypical case of a patient who presented acutely with periorbital pain and optic nerve head edema, and was ultimately determined to have a low-grade optic nerve meningioma.

OBSERVATIONS

A 36-year-old healthy woman presented with acute onset of left periorbital discomfort. She was found to have intact visual acuity, full peripheral vision, and ipsilateral optic nerve edema. MRI imaging revealed a large intraconal mass partially encircling the left optic nerve. Incisional biopsy revealed a diagnosis of meningioma, WHO grade 1.

CONCLUSIONS

Low-grade optic nerve sheath meningiomas may uncommonly present with acute pain and optic nerve head swelling, and absence of classic disease features.

Systemic therapy for recurrent meningioma

INTRODUCTION

Meningioma comprise 20-30% of all primary brain tumors. Notwithstanding surgery and radiotherapy, a subset of patients will manifest recurrent meningioma. Systemic therapy is recommended only when further surgery and radiotherapy are not possible. No prospective study with a high level of evidence is available to inform as to recommendations regarding systemic therapy.

AREAS COVERED

We aim to summarize systemic therapies for recurrent meningioma. Expert commentary: Hydroxurea, temozolomide, irinotecan, the combination of cyclophosphamide/adriamycine/vincristine, interferon-alpha, somatostatin analogs, mifepristone, megestrol acetate, imatinib, erlotinib and gefitinib are considered as having limited efficacy. Potential activity of VEGF (vascular endothelial growth factor) inhibitors such as sunitinib, valatinib, and bevacizumab is suggested in small non-controlled studies and requires validation in randomized trials. The identification of new prognostic markers such as TERT promoter mutations and potential new therapeutic targets, such as KLF4, AKT1, TRAF7, and SMO mutations hopefully facilitate this endeavor.

Medical Management of Meningiomas: Current Status, Failed Treatments, and Promising Horizons

Meningiomas are benign tumors of the central nervous system, with low recurrence risk for World Health Organization (WHO) grade I lesions but a high risk for WHO grade II and III lesions. Current standard treatments include maximum safe surgical resection when indicated and radiation. Only three systemic therapies alpha-interferon, somatostatin receptor agonists, and vascular endothelial growth factor inhibitors are currently recommended by the National Comprehensive Cancer Network for treatment of recurrent meningioma. This paper aims to review medical approaches in the treatment of meningiomas.

The Role of Mifepristone in Meningiomas Management: A Systematic Review of the Literature

OBJECTIVES

We performed a systematic literature review to analyze the clinical application and the safety of mifepristone, a prominent antiprogesterone agent, in meningioma patients.

MATERIALS AND METHODS

A systematic search was performed through Medline, Cochrane, and clinicaltrials.gov databases from 1960 to 2014. Study Selection. Studies were selected through a PICO approach. Population was meningioma patients, meningioma cells cultures, and animal models. Intervention was mifepristone administration. Control was placebo administration or any other drug tested. Outcomes were clinical and radiological responsiveness, safety profile, and cell growth inhibition.

RESULTS

A total of 7 preclinical and 6 clinical studies and one abstract were included. Encouraging results were found in preclinical studies. Concerning clinical studies, the response rate to mifepristone in terms of radiological regression and symptomatic improvement/stability in patients with inoperable meningioma was low. In meningiomatosis, favorable preliminary results were recorded. The safety profile was good. Limitations were as follows. The tumoral expression of progesterone receptors was not analyzed systematically in every study considered.

CONCLUSIONS

No clear evidence exists to recommend mifepristone in inoperable meningiomas. Preliminary encouraging results were found in diffuse meningiomatosis. Mifepristone is a well-tolerated treatment. Patients' selection and hormonal profile analysis in meningiomas are fundamental for a better understanding of its benefit. Multicenter placebo-controlled trials are required.

Historical benchmarks for medical therapy trials in surgery- and radiation-refractory meningioma: a RANO review

BACKGROUND

The outcomes of patients with surgery- and radiation-refractory meningiomas treated with medical therapies are poorly defined. Published reports are limited by small patient numbers, selection bias, inclusion of mixed histologic grades and stages of illness, and World Health Organization (WHO) criteria changes. This analysis seeks to define outcome benchmarks for future clinical trial design.

METHODS

A PubMed literature search was performed for all English language publications on medical therapy for meningioma. Reports were tabulated and analyzed for number of patients, histologic grade, prior therapy, overall survival, progression-free survival (PFS), and radiographic response.

RESULTS

Forty-seven publications were identified and divided by histology and prior therapies, including only those that treated patients who were surgery and radiation refractory for further analysis. This included a variety of agents (hydroxyurea, temozolomide, irinotecan, interferon-α, mifepristone, octreotide analogues, megestrol acetate, bevacizumab, imatinib, erlotinib, and gefitinib) from retrospective, pilot, and phase II studies, exploratory arms of other studies, and a single phase III study. The only outcome extractable from all studies was the PFS 6-month rate, and a weighted average was calculated separately for WHO grade I meningioma and combined WHO grade II/III meningioma. For WHO I meningioma, the weighted average PFS-6 was 29% (95% confidence interval [CI]: 20.3%-37.7%). For WHO II/III meningioma, the weighted average PFS-6 was 26% (95% CI: 19.3%-32.7%).

CONCLUSIONS

This comprehensive review confirms the poor outcomes of medical therapy for surgery- and radiation-refractory meningioma. We recommend the above PFS-6 benchmarks for future trial design.

Intracranial meningiomas in patients with uterine sarcoma treated with long-term megestrol acetate therapy

OBJECTIVE

To report a series of four patients with uterine sarcoma, including one with müllerian adenosarcoma (MA) and three with low-grade endometrial stromal sarcoma (LGESS), who developed intracranial meningiomas while receiving the progesterone agonist megestrol acetate.

METHODS

The hospital records, imaging studies, and pathology slides of four patients who were treated for uterine sarcomas and subsequently developed intracranial meningiomas were reviewed.

RESULTS

All patients underwent surgery for their gynecologic cancers and received maintenance therapy with long-term hormonal suppression with megestrol acetate. Each of the four patients later developed neurologic symptoms secondary to intracranial meningiomas. Three patients had more than one meningioma. Histopathologic examination of all excised tumors showed strong immunoreactivity for progesterone receptors (PRs).

CONCLUSIONS

Patients with uterine sarcoma subtypes LGESS and MA may be predisposed to develop meningiomas, particularly in the setting of long-term treatment with megestrol acetate. Alternatively, preexisting, clinically silent meningiomas in these patients may have progressed to the point of clinical symptoms in the presence of the progesterone agonist megestrol acetate. Without previous imaging studies showing the presence or absence of meningioma before initiation of megestrol acetate treatment, there is no way to draw definitive conclusions regarding this possibility. Clinical and neuroradiologic surveillance for meningiomas should be strongly considered in patients with these uterine sarcoma subtypes, particularly in patients undergoing long-term suppressive therapy with megestrol acetate.

Immunohistochemical investigation of hormone receptors and vascular endothelial growth factor concentration in vestibular schwannoma

OBJECTIVES

To determine if a relationship exists between the presence of estrogen receptors (ER), progesterone receptors (PR), or vascular endothelial growth factor (VEGF) and the size, growth rate, and behavior of vestibular schwannoma tumors.

DESIGN

Nine tumor samples from young female patients with large vestibular schwannoma tumors were preselected because they were presumed to be faster growing, more aggressive tumors. Immunohistochemical staining was performed using monoclonal mouse antibodies to ER, PR, and VEGF.

RESULTS

The mean age of the study sample was 32.3 years, mean tumor size was 3.2 cm, and the average growth rate was 0.4 cm per 2 months. The results of immunohistochemical staining for ER and PR in all nine samples were unequivocally negative. Eight of nine tumor samples stained positive for VEGF, with five demonstrating low intensity and three demonstrating moderate intensity staining.

CONCLUSIONS

There is histopathological evidence for the expression of VEGF in vestibular schwannomas but not for ER and PR. Further studies are necessary to determine the role of VEGF and other molecular pathways in the growth of vestibular schwannomas and the application of anti-VEGF therapy as a potential treatment option in the future.

Brain tumors and hormonal factors: review of the epidemiological literature

BACKGROUND

To date, the etiology of primary tumors of the central nervous system (mainly gliomas and meningiomas) is poorly understood. The role of sex hormones has been suggested, based on clinical, experimental, biological, and epidemiological data.

OBJECTIVE

To review the epidemiological studies on the relation between hormonal factors and the occurrence of glioma and meningioma, in order to identify new research developments.

METHODS

Articles published until September 2010 were selected by considering exogenous and endogenous exposures and specific brain tumors. Standardized information was collected from 20 articles: 15 concerning gliomas and 13 meningiomas.

RESULTS

An increased glioma risk was observed with later menarche and menopause, while a reduced glioma risk was observed with hormone replacement therapy (HRT) and oral contraceptive use, despite duration of use had no effect on risk. Meningioma risk increased after menopause and with HRT use. No clear association was found with pregnancy and breastfeeding.

CONCLUSION

Results are globally concordant with the biologic hypothesis assuming that female sex hormones are protective against glioma and may increase the risk of meningioma. However, new epidemiological studies should be conducted in order to confirm these associations and to refine the role of hormonal factors in brain etiology.

Primary radiotherapy for optic nerve sheath meningioma

Radiotherapy has recently been recognized as the treatment of choice for most primary optic nerve sheath meningiomas (ONSM). Radiotherapy is incorporated into the treatment of non optic nerve sheath meningiomas for unresectable or subtotally resected tumors. Most primary ONSM are not surgically approachable without a high risk of visual deterioration. Radiotherapy has been found to prevent or delay tumor growth for the majority of patients and improve vision in some. We review the rational and current methods of the use of radiotherapy for these tumors.

Multiple meningiomas arising during long-term therapy with the progesterone agonist megesterol acetate

In this report the authors describe a woman with low-grade endometrial stromal sarcoma who was treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy. After receiving megestrol acetate continuously for 19 years for chronic hormone suppression, she began to experience progressive dementia. Magnetic resonance imaging revealed 11 separate intracranial meningiomas of various sizes. The largest lesions were treated with staged angiographically guided embolization and excision. Despite discontinuation of megestrol acetate, the remaining smaller lesions grew slightly in size, requiring further treatment with a combination of excision and gamma knife stereotactic surgery. All of the excised tumors showed positive staining for progesterone receptors on immunohistochemical examination. Prolonged therapy with megestrol acetate could promote the growth of benign intracranial meningiomas in some patients.

Progesterone receptor isoform expression in human meningiomas

The majority of meningiomas express the progesterone receptor (PR), and therefore meningiomas are considered to be progesterone-responsive. In addition, an association has been reported between PR and prognosis. At least two PR isoforms exist, PR-B (116--120 kDa) and PR-A (81 kDa), each of which are likely to have different biological functions. Knowledge of the differential expression of both isoforms is necessary to understand the effects of progesterone on meningioma growth. Therefore, in this study, PR-A and PR-B expression levels were determined in 61 human meningiomas by immunoblotting. Total PR expression levels were determined with a ligand binding assay (LBA) (total PR(LBA)). Both PR isoforms and an additional PR 78 kDa protein (PR-78) were expressed in the meningiomas. Meningiomas expressing more PR-A than PR-B had significantly higher total PR(LBA) levels (P<0.001). The PR-78 band intensity was negatively associated with that of PR-B (r(s)=-0.76, P<0.0001). PR-78 may represent an endogenous degradation product, but a similar regulation pathway in the biogenesis of both PR-B and PR-78 is not excluded. Meningiomas contain both PR isoforms, but in highly variable ratios and this variability may have some biological significance. Most meningiomas express more PR-A than PR-B. Therefore in meningioma, assuming that PR-B is more transcriptionally active than PR-A, progesterone responsiveness could be based on transrepression rather than on transactivation of target genes, and progesterone blockade may only be effective in certain subsets of meningiomas.

Regression of a presumed meningioma with the antiestrogen agent mepitiostane. Case report

This 68-year-old woman underwent a distal gastrectomy for gastric cancer in August 1994. A presumed meningioma of the falx was found incidentally on a staging examination of the gastric cancer, but the meningioma was not treated with surgery. Instead, after gastrectomy the patient received tegafur as adjuvant chemotherapy until February 1996, when she was readmitted to the hospital because of loss of appetite and emaciation but with no recurrence of the gastric cancer. A computerized tomography scan obtained during this second admission showed no change in the meningioma. To improve her general condition, tegafur was discontinued and she was started on a course of the antiestrogen agent mepitiostane. Administration of mepitiostane for approximately 2 years resulted in a marked regression (73%) of the meningioma. This is the first reported case of a presumed meningioma that regressed as a result of use of the antiestrogen agent mepitiostane.

[Supratentorial meningiomas. Diagnosis, surgical results and complications]

Meningiomas are benign tumors arisising from arachnoid cells and represent the commonest asymptomatic intracranial tumors. We analysed 69 supratentorial meningiomas managed by the Neurosurgical Tumor Group of the Clinics Hospital of Medicine School of São Paulo University (September 1995 to September 1997). Age, sex, edema degree, tumor site, surgical complications and mortality were studied. Edema degree was defined by radiological methods (CT and MRI). Forty-seven patients were women and average age was 58 years. Type II of edema degree was predominant (38.7%). Twenty-nine patients had parasagital meningiomas and 40 presented convexity tumors. Simpson I resection was obtained in 48 procedures, II in 18 and III in two surgical removals. Nine cases complicated (transitory deficits, 6; permanent deficit, 1; and infection, 2). Death occurred in two patients. Morbity and mortality had relation with age, falx tumors and attempt of radical surgical removal. Edema degree did not modify mortality and morbidity rates.

The treatment of recurrent unresectable and malignant meningiomas with interferon alpha-2B

OBJECTIVE

Recurrent malignant meningiomas and unresectable meningiomas represent a great therapeutic challenge after the failure of radiation therapy. No effective chemotherapy has been found. We report the preliminary results of the treatment of patients with recurrent unresectable or malignant meningiomas with recombinant interferon alpha-2B (IFN-alpha-2B).

METHOD

Each of six patients with either a recurrent malignant meningioma or an unresectable meningioma was treated with IFN-alpha, administered subcutaneously at a dosage of 4 mU/m2 per day, 5 days per week. Two of the six meningiomas were regular, one was atypical, and three were malignant.

RESULTS

Five of six patients exhibited positive response to treatment; with stabilization of the size of the tumor in four patients and slight regression in one. The responses observed lasted from 6 to 14 months. The toxicity associated with prolonged use of IFN-alpha was mild and well tolerated.

CONCLUSION

These results suggest that IFN-alpha is effective in the treatment of recurrent malignant meningiomas.

Progesterone and estrogen receptors in meningiomas: prognostic considerations

Meningiomas often contain steroid hormone receptors, but the correlation of receptor presence with patient outcome or mitotic index is unclear. Intracranial meningiomas from 70 patients (27 males and 43 females, mean age 52.9 + 1.7 years [mean +/- standard error of the mean], range 15-78 years) were evaluated immunocytochemically for female sex hormone receptors using specific monoclonal antibodies. Prognostic correlations were determined using statistical analyses that included clinical and histological variables. Twenty-eight tumors were benign, 27 had atypical features, and 15 were malignant. Thirty tumors were meningotheliomatous, 11 were fibroblastic, 28 were transitional, and one was secretory. Twenty-nine of the 70 primary tumors recurred (mean interval to recurrence 50.1 +/- 10 months). The mean progression-free follow-up period for patients without recurrence was 82.1 +/- 7.7 months. Nuclear staining for the progesterone receptor (PR) was found in 58 cases (83%) and PR status was scored as 0 (0% nuclei positive), 1 (< 1%), 2 (1-9%), 3 (10-49%), or 4 (> 50%). Only six tumors (8.6%) contained nuclear estrogen receptor (ER) staining, which was limited to a small number of nuclei (< 1%). Fisher's exact test (two-tailed) showed an inverse correlation between tumor grade and PR staining score (p < or = 0.001), with 96% of benign and 40% of malignant meningiomas containing PR-positive nuclei. No correlation between age or histological subtype and PR score was detected. Meningiomas from female patients had more PRs (p < or = 0.05). Analysis of variance revealed that the mitotic index (total counts of mitoses per 10 high-power fields) for tumors with 0 PR staining (18 +/- 4.4) was higher (p < or = 0.0001) than for those with PR scores of 1 to 4 (4.3 +/- 1.9, 5.1 +/- 2, 2.2 +/- 0.8, and 1.7 +/- 0.9, respectively). Univariate analysis indicated that the absence of PR, high mitotic index, and higher tumor grade were significant factors for shorter disease-free intervals. Multivariate analysis showed that a three-factor interaction model, with a PR score of 0, mitotic index greater than 6, and malignant tumor grade, was a highly significant predictor (p < or = 0.0001) for worse outcome in patients harboring meningiomas. These data indicate that the presence of PRs, even in a small number of tumor cells, is a favorable prognostic factor for meningiomas.

[Endocrine treatment of meningiomas: a review]

Meningiomas are benign tumors of central nervous system. They have high rates of relapse and sometimes are not amenable to total removal mainly when involve vital structures. Clinical, epidemiological, biochemical and "in vitro" experiment show evidence that meningioma growth is influenced by steroid hormonal medium. Several clinical trials have explored these meningioma characteristics with the use of substances interfering with steroid actions: RU486 (antiprogestinic and antiglucocorticoid), medroxiprogesterone acetate (antiprogestinic), gestrinone (antiestrogenic e antiprogestinic), tamoxifen (antiestrogenic) and buserelin (LHRH superagonist), beyond of octreotide (somatostatin analog) and bromocriptine (dopaminergic agonist). Other substances have potential for the meningiomas treatment: aminogluthetimide, suramin and trapidil. In this review, we analyzed the literature about these aspects.

Quantitative imaging of estrogen and progesterone receptors, estrogen-regulated protein, and growth fraction: immunocytochemical assays in 52 meningiomas. Correlation with clinical and morphological data

Quantitative imaging of estrogen receptors (ER's), progesterone receptors (PR's), estrogen-regulated protein (pS2), and growth fraction (Ki67) immunocytochemical assays were performed in 52 meningiomas. The results were correlated with clinical (age, sex, hormonal status, and tumor volume and location) and morphological (histological types and grades) data. The authors observed a lack of ER's in all meningiomas but the presence of PR's in 53% of these meningiomas. The immunoreactivity was restricted to tumor cell nuclei. The PR immunocytochemical assay was correlated with tumor location, histological type, histological grade, and pS2 immunocytochemical assay, but not with Ki67 immunocytochemical assay; high PR content was observed in cisternae, transitional, meningothelial, and low-grade meningiomas. Only 11 meningiomas showed more than 1% Ki67 immunoreactive nuclei. These meningiomas were usually located in the convexity and were of high histological grade. Estrogen-regulated protein immunoreactivity was observed in 34 meningiomas but the number of immunoreactive nuclei was low. The pS2 immunocytochemical assay was not related to clinicopathological features but was preferentially observed in PR-negative meningiomas. The results of this study are compared with those previously reported, and the function and regulation of PR's in meningiomas is discussed. The results indicate that 1) regulation of PR's and pS2 proteins in meningiomas differs from regulation in estrogen-dependent tissues such as breast or endometrium; 2) interruption of hormonal therapy in women presenting with a meningioma is not absolutely necessary; 3) meningiomas have different biological properties according to their clinicopathological features; and 4) future studies of hormonal clinical trials should be performed on well-defined meningioma subgroups.

Hormone receptors in initially excised versus recurrent intracranial meningiomas

Intracranial meningiomas from 51 surgical patients consecutively treated during an 18-month period were evaluated for the presence of receptors to progesterone and estrogen. Thirty-eight patients underwent initial resection during this time and 13 underwent reoperation for recurrent disease. With positivity defined as receptor levels greater than 10 fmol/mg of cytosol protein, 84% of all the meningiomas were positive for progesterone receptors, whereas only 33% were positive for estrogen receptors. Among the recurrent meningiomas, 92% showed evidence of progesterone receptors and 54% of estrogen receptors; these figures were not significantly different from the corresponding incidence of 82% and 26%, respectively, among the initially excised tumors. However, the mean concentration of progesterone receptors in the recurrent tumor group was significantly higher when compared to the concentration in the initially excised group (p < 0.02). Twenty meningiomas (39%) were considered to be radiation-induced, since they were removed from patients who had received scalp irradiation during childhood. The incidence and concentration of receptors in the radiation-induced tumors were generally comparable to those in the spontaneous meningiomas. This study confirms previous reports of a high incidence of hormone receptors, mainly for progesterone, in meningiomas. In addition, it shows that in recurrent meningiomas these receptors persist and even increase. The results therefore support hormone treatment for nonresectable meningiomas, especially at recurrence.

Review of skull base surgery approaches: with special reference to pediatric patients

The techniques of skull base surgery attempt to maximize the exposure of a cranial base lesion while using the least amount of brain retraction. Cranial base surgery is not a 'new' area of neurosurgical or otolaryngologic interest, but instead represents a resurgence of efforts to treat difficult lesions involving the cranial base. This resurgence of interest and effort is a product of recent advances in microanatomical knowledge of the cranial base, advances in microsurgical technique, improved neurophysiologic monitoring, and improved collaborative relationships between neurosurgery, otolaryngology and plastic surgery. Furthermore, improved neuroanesthetic techniques allow the surgeon to proceed with surgery without undue concern about time, and improved neuroimaging techniques provide the surgeon with detailed knowledge of the three dimensional characteristics of the tumor and surrounding structures. This review will focus on the surgical management of cranial base tumors primarily affecting the pediatric population. Little has been written on the techniques of skull base surgery as they apply to the pediatric population, since cranially-based tumors are a relatively rare occurrence in this patient population. In most instances, however, many of the 'standard' skull base approaches can be applied to the pediatric patient with few modifications, and in our experience, the pediatric patients have tolerated these approaches as well as their adult counterparts.

Meningiomas

This article reviews the recent literature on the pathogenesis and pathology of meningiomas, contemporary techniques of surgical resection, and new nonsurgical treatments, including radiation and hormone therapy. Factors predisposing to meningioma formation include female sex, previous ionizing radiation, and Type 2 neurofibromatosis. The first factor may act through the expression of sex hormone receptors, especially the progesterone receptor, in these tumors; the other two probably act by causing a deletion on Chromosome 22. The pathological classifications of meningiomas include the traditional division into histological subtypes and the World Health Organization classification that selects characteristics that may lead to recurrence. There is an increasing emphasis on proliferative indices and other characteristics that may predict aggressive behavior in these tumors. On computed tomography, meningiomas are enhancing, well-marginated, dural-based lesions that may have considerable surrounding edema; the cause of the edema is uncertain but may result from secretory products of the tumor. Magnetic resonance imaging with enhancement will demonstrate these lesions accurately and can be used for three-dimensional reconstruction as well. Computed tomography and magnetic resonance imaging have largely replaced angiography in the preoperative diagnosis of meningiomas, but angiographic embolization may be a useful operative adjunct. Although meningioma surgery is sometimes thought of as benign and curative, the reported surgical mortality rate is as high as 14.3% and the reported 10-year survival rate after surgery varies from 43 to 77%. Surgery has advanced most in the management of suprasellar, cavernous sinus, clivus, tentorial, and posterior fossa meningiomas, because new approaches and a better understanding of anatomy have allowed more radical resection. There is still substantial morbidity associated with surgery in these regions, however, and the long-term recurrence rates are still unknown for these new radical techniques. For convexity, parasagittal, lateral sphenoid wing, and olfactory groove meningiomas, complete resection should be the goal and operative morbidity appears to be low. There is a high recurrence rate after surgery. With apparent total removal, the recurrence rate varies from 9 to 20% at 10 years, with subtotal resection varying from 18.4 to 50%. The degree of resection appears to be most important in recurrence, but histopathological features are also important. Recently, radiation therapy has been recognized as a useful adjunct to surgery, and with radiosurgical techniques may become more important in the future. Antiprogesterone therapy appears to have had some success as well, and it or other hormonal therapy may be another future option for residual or recurrent meningiomas.

Inhibitory effect of trapidil on human meningioma cell proliferation via interruption of autocrine growth stimulation

In a previous study, the authors demonstrated that meningioma cells secrete platelet-derived growth factor (PDGF)-like molecules that stimulate their own growth in an autocrine manner. Based on that finding, a study was undertaken to examine the effect of trapidil, a drug known to have an antagonistic action against PDGF, on cell proliferation of human meningiomas in culture. Trapidil showed a dose-dependent inhibition of meningioma cell proliferation in the absence of any exogenous mitogenic stimulation. The maximum effect was observed at a concentration of 100 micrograms/ml, with the decrease in cell growth ranging from 16% to 54% compared to control samples. Trapidil similarly inhibited the basal deoxyribonucleic acid (DNA) synthesis assessed by [3H]-thymidine incorporation in three of seven meningiomas. While the conditioned medium generated from meningioma cells remarkably stimulated the proliferation of meningioma cells (166% to 277% of control), this effect was strikingly inhibited by the addition of trapidil. Trapidil also inhibited conditioned medium-stimulated DNA synthesis, even when there was no effect on basal DNA synthesis. Furthermore, trapidil significantly inhibited the epidermal growth factor (EGF)-stimulated proliferation of meningioma cells. This inhibitory effect on EGF-stimulated cell proliferation was also observed in nontumorous fibroblasts, demonstrating that trapidil is not an antagonist specific to PDGF. The addition of trapidil (30 micrograms/ml) in combination with bromocriptine (1 microM) showed an additive inhibitory effect on the meningioma cell growth compared to trapidil or bromocriptine alone. The overall results suggest that trapidil exhibits an inhibitory effect on meningioma cell proliferation through blocking the mitogenic stimulation induced by autocrine or exogenous growth factors, and may be considered as a possible new approach to the medical treatment of meningiomas.

Presence of dopamine D1 receptors and absence of dopamine D2 receptors in human cerebral meningioma tissue

Preliminary studies have shown that the dopamine D1 receptor is expressed in cerebral meningioma tissue. The current study presents evidence that the iodinated dopamine D1 antagonist [125I]SCH-23982 bound to dopamine binding sites in 33 of the 45 human cerebral meningiomas examined for this. Saturation curves and the linearity of the Scatchard analysis indicate that [125]SCH-23982 binds to a homogeneous population of binding sites. Competition curves reveal the presence of a dopamine D1 receptor by rank order of various dopaminergic and nondopaminergic antagonists ((+)-SCH-23390 greater than (+/-)-SKF-83566 greater than (cis)-flupentixol greater than (+)-butaclamol greater than chlorpromazine greater than 1-sulpiride greater than mianserin greater than (-)-butaclamol). Stereoselectivity was evaluated by (+)- and (-)-butaclamol. The mean (+/- standard deviation) dissociation rate constant was 369 +/- 196 pM with a density of 31.9 +/- 12.5 fmol/mg membrane protein among 33 meningiomas. The dopamine D2 receptor was not present in the 30 meningiomas examined for this. These findings indicate that the dopamine D1 receptor identified is expressed alone and is therefore regulated independent of a D2 receptor in cerebral meningioma tissue. Although the function of the dopamine D1 receptor in cerebral meningiomas has not so far been defined, previous studies have suggested that the D1 receptor might be involved in the control of proliferative growth of meningiomatous tissue.

Mifepristone (RU 486) treatment of meningiomas

Meningiomas are common brain tumours which are generally benign, well circumscribed and slow growing. In a minority of patients complete surgical removal is not possible and re-growth of tumour tissue is a major clinical problem. Most meningiomas contain progesterone receptors. The anti-progestational drug mifepristone (RU 486) binds to these receptors. Ten patients were treated with 12 recurrent or primary "inoperable" meningiomas, all of whom had shown recent neuroradiological and/or ophthalmological evidence of tumour growth. They received 200 mg mifepristone daily for 12 months. Most patients initially had complaints of nausea, vomiting and/or tiredness. In four patients prednisone (7.5 mg/day) was given after which these side-effects subsided. CT scan analysis of tumour size, showed progression of growth of five meningiomas in four patients, stable disease in three patients with three tumours and regression of four tumours in three patients. A decrease in the complaints of headache and an improved general well being was observed in five patients. Two patients died during the treatment period from unrelated causes. Mifepristone treatment resulted in control of tumour growth (= stable disease) in six of 10 patients who had shown recent evidence of tumour growth. In three of these six patients consistent tumour shrinkage was observed.

Neurotensin receptors in human meningiomas

We have investigated the presence of neurotensin receptors in human meningiomas by in vitro binding autoradiography. Ten of the 12 meningiomas tested displayed specific [3H]neurotensin binding. All meningothelial (n = 3) and transitional (n = 5) meningiomas were positive, whereas only 2 of the 4 fibroblastic meningiomas showed measurable concentrations of neurotensin binding sites. Within the tumors, [3H]neurotensin binding was preferentially observed in syncytial areas. Saturation experiments showed that the maximal binding capacity (Bmax) greatly varied among tumors, ranging from low values to more than 290 fmol/mg of protein. All positive tumors had neurotensin binding sites with a dissociation constant (kd) within the nanomolar range and a pharmacological specificity for [3H]neurotensin similar to neurotensin receptors.

Autocrine control of human meningioma proliferation: secretion of platelet-derived growth-factor-like molecules

We have used cell-culture techniques to investigate growth-factor production by human meningioma cells. Meningioma tissue was dispersed with collagenase and the cells grown to high density in tissue-culture flasks. The cultures were used to generate conditioned medium (MEN-CM), which was used to cultivate IMR32 cells (a human neuroblastoma line) and freshly dispersed primary meningioma cells. MEN-CM profoundly stimulated the in vitro growth of both IMR32 and meningioma cells. In addition, H3-thymidine uptake by cultured meningioma cells was increased in a dose-dependent manner by varying concentrations of MEN-CM. A neutralizing anti-body against platelet-derived growth factor (PDGF) completely abolished the stimulatory effects of MEN-CM, whereas an antibody against TGF-alpha was without effect. The mitogenic activity of MEN-CM, as assayed by promotion of H3-thymidine uptake by cultured meningioma cells, eluted from a Sephadex G-100 column in 3 peaks corresponding to molecular weights of greater than or equal to 150, 56 and 28 kDa. Our results show that proliferation of human meningiomas may be under autocrine control via secretion of PDGF-like molecules.

Hormonal dependency of cerebral meningiomas. Part 1: Female sex steroid receptors and their significance as specific markers for adjuvant medical therapy

Female sex steroid receptors were examined in 50 human cerebral meningiomas. For estrogen receptors, high-affinity binding sites (dissociation constant (Kd): 0.05 to 0.2 nM) were found in the cytosolic fraction with a capacity of less than 4 fmol/mg protein in 10 meningiomas using a dextran-coated charcoal (DCC) assay. In the same cytosolic fraction, the solid-phase enzyme immunoassay revealed only one cytosol with a positive colorimetric reaction equal to 5 fmol/mg protein. However, in the nuclear compartment, none of the tumors stained positively for estrogen receptors with immunohistochemical techniques. In addition, the most convincing evidence for the absence of estrogen receptors was obtained by in situ hybridization using an oligonucleotide probe complementary to a fraction of the human receptor messenger ribonucleic acid (mRNA). In none of the 50 meningiomas was the expression of estrogen mRNA coding for the estrogen receptor detected. For progesterone receptors, high-affinity binding sites (Kd: 0.3 to 2.6 nM) were found in 49 of the 50 tumors using a DCC assay. In the same cytosols, solid-phase enzyme immunoassay revealed that each tumor was positive for progesterone receptors. However, in the nuclear compartment, only five tumors had partially positive staining for progesterone receptors with immunohistochemical techniques. Within the confines of this study, it is concluded that: 1) the estrogen receptor is generally absent in meningioma tissue, and 2) the progesterone receptor is mainly absent in the nuclear compartment, leading to the conclusion that the cytosolic progesterone receptor may be an inactive form. This study suggests that female sex steroid receptors are not primarily involved in the proliferative rate of cerebral meningiomas and that they are of no current significance as markers for adjuvant medical therapy of most meningiomas.

Hormonal dependency of cerebral meningiomas. Part 2: In vitro effect of steroids, bromocriptine, and epidermal growth factor on growth of meningiomas

Cell culture and biochemical techniques have been employed to examine the effects of steroids, bromocriptine, and epidermal growth factor (EGF) on the growth and proliferative potential of meningiomas. In cell culture, the growth of meningiomas was not altered by progestogens, antiprogestogens, or 17beta-estradiol. The progestogen, norethisterone, had no effect on the uptake by meningiomas cell cultures of 3H-thymidine. Furthermore, cytosolic deoxyribonucleic acid (DNA) polymerase activity of meningiomas did not correlate with the progesterone receptor status of the same tumors. In contrast, the androgen antagonists, cyproterone acetate and 11-alpha-hydroxyprogesterone, and the dopamine agonist, bromocriptine, all inhibited the in vitro growth of meningioma cells. The growth of meningioma cell cultures was stimulated by EGF, and there was a positive correlation between the EGF content and DNA polymerase activity in meningioma cytosols. These results demonstrate that female sex steroids do not influence growth of meningiomas in vitro, whereas antiandrogens and bromocriptine have an antiproliferative effect. Consequently, bromocriptine and antiandrogens may have a role in the medical treatment of meningiomas. In addition, these results suggest that EGF may be involved in the genesis and/or progression of meningiomas.

Eleven times recurrences of a parasagittal falxmeningioma. Case report

Although meningiomas are of benign character and generally of encapsulated growth, recurrence is a known problem in treatment. The authors present the time course of a recurrent parasagittal meningioma of the falx, which recurred eleven times. Despite modern radiological diagnostic methods, which made early diagnosis of recurrent tumour possible, and the use of modern microsurgical techniques with radical tumour extirpation and followed by radiotherapy, the fatal course of benign tumour disease could not be stopped.

Steroid hormone and epidermal growth factor receptors in meningiomas

A prospective study of steroid hormone and epidermal growth factor receptor expression in 57 meningiomas is presented. Scatchard analysis of radioligand binding identified 20% of meningiomas as expressing classical oestrogen receptors (ER) at levels below that normally accepted for positivity, the remainder being negative. ER could not be visualized in any meningioma using immunocytochemistry. Alternatively, 74% of meningiomas demonstrated the presence of progesterone receptors (PR) by Scatchard analysis, the specificity of which could not be attributed to glucocorticoid or androgen receptors. Confirmation of classical PR presence was determined by immunocytochemical staining. The presence of epidermal growth factor receptor (EGFR) was demonstrated in 100% of meningiomas using immunocytochemical staining. These data are reviewed in the context of previously reported results and are discussed in relation to the potential for medical therapy as an adjunct to surgery.

Effect of steroids and antisteroids on human meningioma cells in primary culture

Human meningiomas are rich in progestin receptors but virtually devoid of oestrogen receptors. We have studied the hormonal sensitivity of meningioma cells in vitro during 8 days of primary culture in the presence of different steroids and antisteroids. On day 8 the thymidine labelling index (TLI) was determined as a measure of cell growth. To date 30 cultures have been established from 39 tissue specimens. 13 cultures had a TLI below 1.0 and their growth were not affected by hormones. The TLI of the other 17 cultures was 3.0 +/- 1.7 (mean +/- SD; range 1.2-7.7). Following culture in the presence of 1 and 10 nM progesterone TLI was 83 +/- 28% (n = 9) and 61 +/- 29% (n = 3) of that of the control cultures respectively. Although in individual cultures occasional differences were found, the overall values are not statistically different from 100. Similarly, 1 nM of oestradiol and testosterone had no effect on the TLI (n = 3). Tamoxifen at 1 nM increased the TLI to 138% in one culture and decreased it to 66% of the control in another. The antiprogestin mifepristone (RU 486) in concentrations of 0.1, 1.0, 10, 100 and 1000 nM decreased the TLI to 72 +/- 30; 54 +/- 20; 55 +/- 20; 59 +/- 18 and 65 +/- 10 respectively (n = 6-15; P less than 0.05 vs control). It is concluded that although a growth promoting effect of progestins on meningioma could not be shown, the therapeutic possibilities of antiprogestins warrant further investigation.

Optic nerve sheath meningioma: diagnostic features and therapeutic alternatives

Twenty-two cases of optic nerve sheath meningioma were reviewed. The clinical features included slowly progressive visual loss in every case. Orbital signs of limited ocular movements and mild proptosis were present in only a third of cases; gaze-evoked amaurosis occurred in 3 cases. The disc was abnormal in every case, usually swollen if vision was 6/12 or better, atrophic if the vision worse than 6/12. Optociliary shunt vessels occurred in 5 patients and were of diagnostic significance. The diagnosis was made by a high-resolution CT scan of the orbits showing tubular expansion of the optic nerve sheath. Calcification of the optic nerve was present in 12 cases. Tubular expansion of the optic nerve sheath may occur in raised intracranial pressure, optic nerve glioma, granuloma, lymphoma or metastatic disease. In the absence of calcification these alternative diagnoses must be considered. Surgery, undertaken for the intracranial component of the tumour, did not halt progressive visual loss.