J Neurooncol (2013) 115:401–409 DOI 10.1007/s11060-013-1231-2
CLINICAL STUDY
Gliomas of the posterior fossa in adults Ido Strauss • Tali Jonas-Kimchi • Felix Bokstein Deborah Blumenthal • Jonathan Roth • Razi Sitt • Jefferson Wilson • Zvi Ram
•
Received: 3 March 2013 / Accepted: 18 August 2013 / Published online: 27 August 2013 Ó Springer Science+Business Media New York 2013
Abstract Infratentorial gliomas are relatively rare tumors compared to their supratentorial counterparts. As such they have not been extensively characterized as a group and are usually excluded from clinical studies. Using our database we aimed to characterize adult gliomas involving the posterior fossa with respect to their clinical behavior and prognostic factors. We reviewed our neurosurgical and neuro-oncological data bases for adult patients diagnosed with gliomas involving the posterior fossa between 1996 and 2010. Of 1,283 glioma patients, 57 patients with gliomas involving the posterior fossa were identified (4.4 %). Tumors were further classified by location as primary brainstem (n = 21) and primary cerebellar (n = 18) tumors. On univariate analysis survival was correlated to tumor grade and KPS. In addition we have identified a unique group of patients (n = 18) with previously diagnosed supratentorial gliomas who subsequently developed noncontiguous secondary infratentorial extension of their
Electronic supplementary material The online version of this article (doi:10.1007/s11060-013-1231-2) contains supplementary material, which is available to authorized users. I. Strauss J. Roth R. Sitt Z. Ram (&) Department of Neurosurgery, Tel Aviv Medical Center, 6 Weizman Street, 64239 Tel Aviv, Israel e-mail:
[email protected] T. Jonas-Kimchi Neuroradiology Unit, Tel Aviv Medical Center, Tel Aviv, Israel F. Bokstein D. Blumenthal Neuro-Oncology Division, Tel Aviv Medical Center, Tel Aviv, Israel J. Wilson Department of Neurosurgery, Toronto Western Hospital, Toronto, ON M5T 2S8, Canada
tumors with subsequent rapid clinical deterioration. Gliomas of the posterior fossa comprise a heterogeneous group of tumors. Histological grade of the tumor was found to be the main prognostic factor. Survival of primary cerebellar gliomas is comparable to supra-tentorial gliomas, while brainstem gliomas in adults fare better than in the pediatric population. Secondary extension of supratentorial gliomas to the posterior fossa signifies a grave prognosis. Keywords Glioma Posterior fossa Brainstem Cerebellum Secondary extension
Introduction Gliomas are the most common primary brain tumors comprising approximately 33 % of all primary brain tumors [1, 2]. These tumors are classified by the WHO according to their cell of origin and the degree of malignancy into grade I–IV [3]. The most common location in adults is the cerebral hemispheres with infratentorial gliomas being a rare entity [2, 4–7]. Due to their rarity, infratentorial gliomas in adults are poorly characterized and not much is known about their natural history and clinical behavior. Infratentorial tumors are more prevalent in the pediatric population and most of the current knowledge about infratentorial gliomas is derived from the pediatric literature. However, there are some fundamental differences between the clinical behavior of pediatric tumors and their adult counterparts, and it is not clear what, if any, conclusions can be drawn from the pediatric literature regarding adult tumors. In adults, supratentorial low-grade gliomas (LGG) usually progress to high-grade gliomas (HGG), while in children such malignant transformation is rare [8–10].
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Moreover, it has been shown in several series that a substantial number of partially resected cerebellar LGG in children can spontaneously regress [8, 9, 11]. Interestingly, brainstem gliomas (BSG) in adults have been found to be less aggressive than their pediatric counterparts [12, 13]. We have retrospectively reviewed our neuro-oncological database for adult patients with gliomas of the posterior fossa, in an attempt to better characterize the clinical behavior and prognostic factors of these tumors.
Patients and methods Between January 1996 and December 2010 we detected 1,283 adult patients ([18 years) diagnosed with brain glioma. All patients with a diagnosis of glioma with an astrocytic or oligodendroglial origin involving the posterior-fossa were selected for the study cohort. Age, KPS at presentation, histopathology and survival were recorded. In addition, the clinical presentation, imaging findings, the neurosurgical and non-surgical treatment modalities used were noted. The study was approved by our hospital ethics committee. Statistical analysis Survival curves and median survival times were analyzed based on the Kaplan–Meier product-limit method. Multiple univariate analyses using the log-rank test were performed to investigate the association between survival and categorical demographic and treatment related variables. For the continuous variable age a univariate Cox proportionalhazards test was performed. Finally, in order to understand the independent effects of individual covariates on survival, a multivariate Cox proportional-hazards model was generated, which included as covariates all variables with a p value less than 0.10 in the univariate analyses. A p value for the Chi square test assessing the collective proportionality of the covariates \0.05 was considered to provide evidence of non-proportionality.
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patients (31.5 %) harbored a posterior fossa glioma that was a non-contiguous extension of a previously diagnosed supratentorial glioma (secondary involvement). For survival analysis patients were also dichotomized as high (grade III & IV glioma) versus low (grade I & II glioma). Univariate analysis using the log-rank test identified histopathological grade (p \ 0.001) and KPS (p = 0.01) as significantly associated with survival (Table 1). Univariate Cox regression analysis evaluating age showed a trend toward higher hazard of death with increasing age (p = 0.06). For further analysis patients were categorized, based on clinical and radiological features, as having primary versus secondary involvement of the posterior-fossa (Group 3). Primary posterior-fossa gliomas were further subclassified according to the originating site of the tumor as brainstem (Group 1) or cerebellar gliomas (Group 2; Fig. 1a, c, d). On log-rank test differences in survival approached significance between location groups (p = 0.052). A multivariate Cox proportional-hazards model was constructed, including a total of three predictor variables (age, grade and location), all of which had p values \0.10 in the univariate analysis (Table 2). This adjusted analysis revealed that histopathological grade significantly predicts survival with high-grade patients experiencing higher hazard of death. Brainstem gliomas We identified 21 patients with gliomas of the brainstem (Supplementary Table 1). Male predominance was noted (14 males/7 females), with a median age at presentation of 38 years (range 19–81). The primary presenting symptoms were cranial nerve deficits (68 %) and gait disturbance (52 %). Median duration of symptoms prior to diagnosis was 4 months (range 0.5–60). There were 14 low grade (3 pilocytic, 11 grade-II astrocytoma) and 7 high-grade tumors (3 AA, 4 GBM; Supplementary Table 1). Diffuse non-enhancing brainstem involvement was categorized as low-grade tumor [12]. Of the eight patients with diffuse
Results
Table 1 Results of univariate analyses exploring the association between survival and individual demographic and treatment variables
Fifty-seven adult patients with gliomas of the posterior fossa were identified. This represents approximately 4.4 % of all glioma patients treated during those years (n = 1,283). The median age at diagnosis was 40 years (range 19–81 years); there were 22 females. Overall median survival of the entire cohort was 40.1 months (range 1.2–206 months). Twenty-eight patients (49 %) had HGG (17 GBM, 11 AA) and 29 patients (51 %) LGG (17 pilocytic, 12 grade II astrocytoma). Brainstem gliomas comprised 37 % (21/57) of the cohort and cerebellar gliomas 31.5 % (18/57). Eighteen
Covariate
Chi square statistic
Grade
1
123
KPS
Degree of freedom
p value
1
\0.01
Hazard ratio –
2
0.012
–
Location Gender
1
2 1
0.052 0.69
– –
Radiation Therapy
1
1
0.22
–
1
1
0.059
1.02
Age a
a
Cox proportional hazards test used since non-categorical variable
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Fig. 1 a Kaplan–Meier plots showing overall survival of patients with gliomas involving the posterior fossa according to group (see text). b Kaplan–Meier plots showing survival for patients with secondary extension of gliomas to the posterior fossa from the initial and secondary diagnosis. Kaplan–Meier survival curves for low- (c),
and high-grade (d) gliomas according to group. e Kaplan–Meier plots comparing survival for low- and high-grade brainstem gliomas. f Kaplan–Meier plots comparing survival for low- and high-grade cerebellar gliomas. Abbreviations: LGG low grade gliomas, HGG high grade gliomas, BSG brainstem gliomas
BSG, seven were diagnosed based on characteristic MR imaging; only 1 patient underwent a stereotactic biopsy that was inconclusive. Surgical treatment was performed in 11 patients and consisted of stereotactic biopsy in 7
patients and tumor resection in 4 exophytic tumors (3 pilocytic astrocytomas, 1 AA). Gross total resection was achieved in all three pilocytic astrocytoma (PA) cases. Of the 7 patients with HGG, only one underwent subtotal
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Table 2 Multivariate Cox proportional hazard model Pathology
DF
Parameter estimate
p value
Hazard ratio
Grade
1
2.27068
\0.0001
9.686
Age
1
0.01127
0.3373
1.011
Group 2
1
-1.07349
0.0443
0.342
Group 3
1
0.36654
0.4369
1.443
Group 1(ref)
resection, while the other six underwent stereotactic biopsy only. 15 patients received radiotherapy, including 8 patients with diffuse BSG, 1 patient with partial resection of a PA and 6 patients with HGG (one HGG patient was not treated due to poor performance status). Median survival for all BSG patients was 38.3 months (range 2.4–170.9 months). Median survival for high-grade BSG was 6.3 months (range 2.4–32.2 months; Fig. 1e). Seven of fourteen patients with low-grade brainstem pathologies are still alive (3 lost to follow-up, 4 deceased), for diffuse BSG mean survival was 46.5 ± 24.5 months and for PA of the brainstem mean survival was 116.4 ± 66.5 months. Cerebellar gliomas The second subgroup consisted of 18 patients with gliomas primarily involving the cerebellum (Supplementary Table 2). The cerebellar hemispheres were more commonly involved than the vermis (15 and 3 patients, respectively), one patient had multifocal disease and one patient had brainstem involvement. Median age at presentation was 42.5 years (range 19–77 years). The most common presenting symptoms were ataxia (44 %) and headaches (39 %). Mean duration of symptoms prior to diagnosis was 4.9 ± 8.3 months (range 1 week– 24 months). Surgical treatment consisted of stereotactic biopsy in two patients, incomplete resection in five and gross total resection in 11 patients. Pathologies consisted of nine low-grade astrocytomas (grade I, Supplementary Table 2) and nine HGG (grade III/IV, Supplementary Table 2). Postoperative external beam radiation was given to 7 of 9 patients with HGG and to one patient with LGG who had had incomplete resection of his tumor. Two patients with HGG did not receive additional treatment due to poor functional status and advanced age. Eight patients received adjuvant chemotherapy using a variety of regimens reflecting changes in treatment protocols over time. Five patients with HGG who were diagnosed after 2005 received combined treatment consisting of radiation with temozolomide according to the ‘‘EORTC (European Organization for Research and Treatment of Cancer) protocol’’ [14]. Overall mean survival for cerebellar gliomas was 59.3 months, Kaplan–Meier survival data are presented in
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Fig. 1. When we further subdivided these patients into low and high-grade pathologies two distinct survival patterns emerged (Fig. 1f). The median survival for the 9 patients with high-grade pathologies was 15.3 months (range 2–56 months) while 8 of 9 patients with low-grade pathologies are alive with a mean follow up of 97.6 months (range 25–206.5 months). Patients with low-grade pathologies of the cerebellum were younger than patients with HGG (mean age 37 ± 9.7 vs. 55 ± 20.8 years), and underwent complete tumor resection more often than patients with HGG (8/9 patients compared to 5/9, respectively). The only patient with incomplete resection of his low-grade tumor was also the only one who received radiotherapy. This patient developed malignant transformation of her tumor 2 years later and subsequently died. Posterior fossa extension of supratentorial gliomas We identified 18 patients who had previously been diagnosed with a supratentorial glioma and have developed late infratentorial extension of their tumor (Fig. 2). This phenomenon occurred in 6 LGG (4 grade II astrocytoma, 2 grade II OD) and 12 HGG (5 AA, 6 GBM and 1 gliomatosis-cerebri; Table 3). The remote posterior fossa lesions were adjacent or surrounded the fourth ventricle, most of them in a non-symmetrical way (14/18). In one patient the posterior-fossa lesion involved only the pons. Although the lesions were small they caused mass effect on the 4th ventricle including displacement or narrowing of the ventricle in 9/18 cases. (Fig. 2a, c, e). The lesions were all hyperintense on the MRI Flair weighted images. Most of the lesions were non-enhancing even if the primary supratentorial tumor was enhancing (4/12 enhancing lesions). The overall median survival from the initial diagnosis of the supratentorial tumor was 94 months (range 8.5–190 months) and depended mainly on the grade of the primary tumor. Median survival from the time of the diagnosis of the posterior-fossa involvement was 19.5 months, for the entire group (range 1.2–60 months) (Fig. 1b). Mean interval between the diagnoses of supraand infratentorial involvement was 52 ± 53.5 months. Most patients were followed with serial MRI; surgical treatment was indicated in only 2 patients who developed symptoms related to mass effect on the 4th-ventricle. On univariate analysis the main prognostic factor was tumor grade. Median survival for HGG was 22.8 months from the first diagnosis (range 8.5–87 months) and 11 months from the diagnosis of the posterior-fossa involvement (range 1.2–22.7 months). For LGG median survival was 140 months from the first diagnosis (range 94–190 months) and 47.5 months from the diagnosis of the posterior fossa involvement (range 2.2–60 months).
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Fig. 2 Secondary extension of supratentorial gliomas to the posterior fossa. a FLAIR MRI showing a left frontal low grade glioma (left panel) and the posterior fossa (middle panel) at the time of diagnosis. The right panel demonstrates a noncontiguous peri-4th ventricular lesion that developed 6 years later. b FLAIR MR images demonstrating supratentorial low-grade glioma (left panel) and the posterior fossa (middle panel) at the time of diagnosis; 3.5 years later follow up MRI shows peri-4th ventricular FLAIR changes (right panel). c Right Thalamic GBM (left panel) with no involvement of the posterior fossa (middle panel) at the time of diagnosis. Two years later a paravermian lesion is demonstrated on FLAIR images (right panel). d Left frontal GBM at time of diagnosis with no involvement of the posterior fossa. MRI performed 11 months later shows paraventricular FLAIR changes. e Left Thalamic GBM protruding into the left ventricle, two years later secondary progression in the posterior fossa was diagnosed. FLAIR fluid-attenuated inversion recovery sequence
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406 Table 3 Patients diagnosed with secondary extension of supra-tentorial tumor to the posterior fossa
a
Alive
AA anaplastic astrocytoma, AO anaplastic oligodendroglioma, GBM glioblastoma, GTR gross total resection, HGG high grade glioma, LGG low grade glioma (all grade II astrocytoma), OD oligodendroglioma
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Patient
Age (years)
Gender
Pathology
Interval (months)
Survival (months)
1
27
Male
LGG
42.2
54.6
2
20
Female
AA
0
20
3
32
Male
GBM
10.7
7.4
4
27
Male
LGG
34.5
60.2
5
36
Female
Grade II OD
146
46.1
6
30
Female
GBM
24
10.5a
7
21
Male
AA
30
8
8
40
Male
Gliomatosis
0
22.8
9
65
Male
AA
0.3
8
10
43
Female
Grade II OD
145
36.3a
11 12
62 56
Female Female
GBM GBM
4 11.5
16.2 1.2
13
57
Male
GBM
54
1.5a
14
29
Male
AA
77
11.2a
15
41
Male
LGG
123.5
2.2
16
27
Male
LGG
147.5
11.9a
17
34
Female
AA
63
5.7a
18
56
Male
GBM
23
6.1a
Discussion Gliomas of the posterior fossa are rare. According to published reports they comprise approximately 1 % of all glioma cases [2, 4–6]. In our series the incidence of posterior fossa gliomas was 4.6 % of all glioma patients. This higher than expected incidence may be partially explained by the inclusion of the unique group of patients diagnosed with secondary posterior-fossa involvement of a previously diagnosed supratentorial glioma. Traditionally, gliomas of the posterior-fossa are grouped by location into cerebellar and brainstem gliomas. Each group is usually further subdivided according to radiological and/or histological characteristics of low- and highgrade pathology. In our series, when tested for significance of prognostic factors, grade of the tumor and KPS at diagnosis were found to be predictive of survival, with a trend toward a higher hazard of death with increasing age, which did not reach statistical significance. This can probably be explained by the uniformly dismal prognosis of HGG, in contrast to that of LGG of both brainstem and cerebellum, which display a relatively indolent course. Posterior fossa extension of supratentorial gliomas A unique group of patients only sparsely reported previously comprised of 18 patients with supratentorial gliomas who also had infratentorial extension of their tumor. The extension into the posterior fossa was radiologically
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noncontiguous with supratentorial tumor. All secondary tumors in the posterior fossa were intra parenchymal around the fourth ventricle without evidence for other CSF disseminated loci. While the majority of these 18 patients had dissemination to the posterior fossa later in their disease history, 2 had concurrent disease dissemination adjacent to the 4th ventricle at the time of their primary supratentorial diagnosis, raising the question of multicentricity. The incidence of multiple glial tumors is estimated to be 1–10 % of all gliomas cases [15–18]. These tumors are traditionally classified as either multifocal or multicentric, depending on whether the various lesions represent secondary expansion of the primary site (multifocal) or are truly multiple primary lesions (multicentric) [15]. Suggested routes of tumor dissemination include infiltration along white matter pathways and blood vessels or via the CSF [15]. The capacity for leptomeningeal and/or subependymal spread is a feature of all gliomas irrespective of degree of differentiation [19]. One needs to consider that the concept of multicentricity versus multifocality was conceived in the pre-MRI era [15]. Newer studies have argued against the occurrence of true multicentric gliomas and suggested that most are actually multifocal and result from an active migratory process [16]. Multifocal disease involving the posterior fossa is considered rare. Roth et al. [20] have previously found and described a pattern of posterior fossa involvement in a small group of patients with supratentorial LGG. Regions surrounding the 4th ventricle appear to be the most common site for this type of
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tumor extension. Interestingly, Weber et al. [5] reported five patients with cerebellar GBM who relapsed both locally and with an extension to the supratentorial region. Our current series shows that appearance of secondary posterior fossa involvement predicts a poor prognosis, as has been previously described for multifocal gliomas [15– 17]. Surgical or radiation treatment of these patients should be reserved for symptomatic lesions. As most of these tumors were not biopsied at the time of progression we cannot exclude a malignant transformation of the original tumor that affected survival, however in the two LGG (both grade II astrocytoma) cases that were biopsied the histology of the posterior fossa extension was consistent with the primary supratentorial tumor. Recent advances in the molecular biology and genetics of glioma such as IDH1/ IDH2 mutations [21] will facilitate future studies aimed to better characterize this pattern of posterior fossa involvement that has probably been under-diagnosed [20, 22]. Although there is no radiologic evidence of contiguity, the mechanism of dissemination is likely that of subependymal spread, as the posterior fossa tumor is predictably in areas surrounding the fourth ventricle (Fig. 2). Brainstem gliomas Brainstem gliomas in adults are rare and their clinical behavior not well defined. A few recent studies have shown these tumors to be less aggressive than in children [23–26]. Selvapandian et al. [23] compared clinical, radiological and pathological characteristics of BSG between children and adults, and found that diffuse BSG was more prevalent in the pediatric population (41.2 vs. 11.1 % in adults) and that survival was significantly shorter in children. Kesari et al. [25] in a review series of 101 adult BSG have found that tumor location, age at diagnosis and tumor grade were significantly related to survival. Based on clinical, radiological and histological features Guillamo et al. [24] succeeded in classifying most patients into one of three groups: diffuse intrinsic LGG, malignant gliomas and other lesions. They found that diffuse brainstem involvement in adults is usually associated with low-grade pathology and a more indolent clinical course than in children. In contrast, focal enhancement of the brainstem tumor was associated with high-grade pathology and a grave prognosis. Our findings are concordant with the above referenced studies. The most important factor predicting long-term outcome is the histological grade of the tumor. Cerebellar gliomas High-grade gliomas of the cerebellum are rare tumors in both adults and pediatric population and the literature on this entity is limited [4–6, 27–31]. Currently, patients with
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cerebellar GBM are excluded from clinical studies based on the assumption that the clinical course of these tumors is worse than their supratentorial counterparts [4, 6]. Levine et al. [7] found median survival of patients with cerebellar GBM to be less than for cerebral GBM. In contrast, other more recent series have reported the survival of patients with posterior-fossa HGG to be comparable to cerebral HGG [5, 6, 28, 29, 31]. Djalilian and Hall [6] reported on 7 cases and reviewed 71 cases of cerebellar HGG published between 1975 and 1994. The overall median survival was found to be 18 months (range 9-26 months), with median survival for grade-IV tumors of 11 months and 32 months for grade-III tumors. Surgical resection (as opposed to biopsy) and radiation treatment were associated with prolonged survival. Weber et al. [5] in a multi center study retrospectively assessed 45 patients with cerebellar GBM. They found that survival in this group of patients was comparable to the reported survival rates of supratentorial GBM. Progression was local in all cases, and the authors recommended limited field radiation therapy as the primary therapeutic modality [32]. Brainstem invasion was common and constituted a poor prognostic factor. In a recent study Jeswani et al. [31] used the Surveillance, Epidemiology and End Result (SEER) registry to identify patients diagnosed with cerebellar GBM between 1973 and 2008 and demonstrated a comparable survival between cerebellar and supratentorial glioblastoma patients. Younger age and radiation therapy were significantly associated with improved survival outcome for patients with cerebellar GBM. The optimal treatment for infratentorial HGG has not been established. High dose limited field irradiation of the primary tumor site may be beneficial for these patients [5, 6, 28, 31, 32]. One of the main findings of our study, consistent with other recent series [5, 31], is that primary cerebellar HGG probably behave in a similar clinical way to supratentorial HGG and should be treated with standard protocols [29, 31]. Thus, the common practice to exclude cerebellar gliomas from clinical studies should be reconsidered. Low-grade cerebellar gliomas in our series were found to be grade I in all our patients. Our data support the concept that radiation has no role in the initial treatment of these lesions [9, 10, 33, 34], as none of the completely resected tumors received radiation or recurred. A recent study by Bagley et al. [35] found that cerebellar LGG (especially grade-II glioma) had a more favorable prognosis compared to their supratentorial counterparts. Genetic characterization of IDH1/IDH2 and BRAF mutations could also help in the correct diagnosis of cerebellar glioma and help guide treatment [36, 37]. Radiation treatment should be reserved for recurrent unresectable grade I tumors [33, 38, 39]. The only malignant transformation of cerebellar PA was observed in a patient who
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received radiation therapy 1 month after incomplete resection and was diagnosed with a recurrent grade IV tumor 2 years later. Although we cannot prove a direct relation between radiation treatment and malignant transformation, this phenomenon has been described before [5, 6, 8, 10].
Conclusions Primary gliomas of the posterior fossa are relatively rare; however glioma dissemination to the posterior fossa may be under-diagnosed in patients with known supratentorial gliomas. Prognosis of infratentorial gliomas is mainly dependent on the histological grade of the tumor, with prognosis of primary cerebellar HGG being comparable with supratentorial HGG. Secondary extension of supratentorial gliomas to the posterior fossa is a new clinical entity, which signifies rapid clinical deterioration and entails a grave prognosis. Focal treatment of the involved areas with radiation may palliate symptoms and possibly control disease. Conflict of interest
None.
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