J Neurosurg 121:1189–1200, 2014
©AANS, 2014
Results of immunohistochemical staining for cell cycle
regulators predict the recurrence of atypical meningiomas
Clinical article
Min Soo Kim, M.D.,1 Kyu Hong Kim, M.D., Ph.D.,1 Eun Hee Lee, M.D., Ph.D., 2
Young Min Lee, M.D.,1 Sung-Hun Lee, Ph.D., 3 Hyung Dong Kim, M.D., Ph.D., 4
and Young Zoon Kim, M.D., Ph.D.1
Department of Neurosurgery and Division of Neurooncology, and 2Department of Pathology, Samsung
Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon; 4Department of
Neurosurgery, Dong-A University Medical Center, Dong-A University College of Medicine, Busan, South
Korea; and 3Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer
Center, Houston, Texas
1
Object. The aim of this study was to evaluate the role of certain cell-cycle regulatory proteins in the recurrence
of atypical meningiomas. These proteins were analyzed with immunohistochemical staining to identify predisposing
factors for the recurrence of atypical meningiomas.
Methods. The authors retrospectively reviewed the medical records of patients with atypical meningiomas diagnosed in the period from January 2000 to June 2012 at the Department of Neurosurgery at Samsung Changwon
Hospital and Dong-A University Medical Center. Clinical data included patient sex and age at the time of surgery,
presenting symptoms at diagnosis, location and size of tumor, extent of surgery, use of postoperative radiotherapy,
duration of follow-up, and recurrence. Immunohistochemical staining for cell-cycle regulatory proteins (p16, p15,
p21, p27, cyclin-dependent kinase [CDK] 4 and 6, phosphorylated retinoblastoma [pRB] protein, and cyclin D1)
and proliferative markers (MIB-1 antigen, mitosis, and p53) was performed on archived paraffin-embedded tissues
obtained during resection. The recurrence rate and time to recurrence were assessed using Kaplan-Meier analysis.
Results. Of the 67 atypical meningiomas eligible for analysis, 26 (38.8%) recurred during the follow-up period
(mean duration 47.7 months, range 8.4–132.1 months). Immunohistochemically, there was overstaining for p16 in
44 samples (65.7%), for p15 in 21 samples (31.3%), for p21 in 25 samples (37.3%), for p27 in 32 samples (47.8%),
for CDK4 in 38 samples (56.7%), for CDK6 in 26 samples (38.8%), for pRB protein in 42 samples (62.7%), and for
cyclin D1 in 49 samples (73.1%). Multivariate analysis using the Cox proportional-hazards regression model showed
that incomplete resection (HR 4.513, p < 0.001); immunohistochemical understaining for p16 (HR 3.214, p < 0.001);
immunohistochemical overstaining for CDK6 (HR 3.427, p < 0.001), pRB protein (HR 2.854, p = 0.008), and p53
(HR 2.296, p = 0.040); and increased MIB-1 labeling index (HR 2.665, p = 0.013) and mitotic index (HR 2.438, p =
0.024) predicted the recurrence of atypical meningiomas after resection.
Conclusions. Findings in this study indicated that p16, CDK6, and pRB protein were associated with the recurrence of atypical meningiomas.
(http://thejns.org/doi/abs/10.3171/2014.7.JNS132661)
Key Words • atypical meningioma • p16 • CDK6 • RB protein • recurrence • immunohistochemistry • oncology
M
are tumors that arise from meninges
of the brain and the spinal cord. They represent
approximately 20% of all primary intracranial
eningiomas
Abbreviations used in this paper: CDK = cyclin-dependent
kinase; GTR = gross-total resection; NF2 = neurofibromatosis Type
2; pRB = phosphorylated retinoblastoma; p16 = p16INK4A; RFS =
recurrence-free survival; ROC = receiver operating characteristic.
J Neurosurg / Volume 121 / November 2014
tumors and are divided into benign, atypical, and malignant subtypes based on histopathological criteria.38
Among these subtypes, atypical meningiomas are reported to account for 20%–35% of all meningiomas and
represent an intermediate subtype between benign and
This article contains some figures that are displayed in color
on­line but in black-and-white in the print edition.
1189
M. S. Kim et al.
anaplastic meningiomas in the WHO classification.6,35,39,49
Although benign meningiomas (WHO Grade I) are generally slow growing and have a low recurrence rate after
gross-total resection (GTR),27,45 atypical meningiomas
are more locally aggressive and demonstrate more rapid
tumor progression. The literature suggests they have a
5-year recurrence rate of approximately 40% in the absence of postoperative radiotherapy.8,19,29,35 Atypical meningiomas are also associated with significantly increased
mortality. Although GTR, when possible, is widely accepted as the standard of care for benign meningiomas,
a purely neurosurgical approach may be inadequate for
atypical meningiomas. Immediate adjuvant radiotherapy
is clearly beneficial for malignant meningiomas, while its
role for the atypical subtype is still under debate. Nonetheless, postoperative radiotherapy is frequently chosen
in cases of atypical meningiomas, despite the absence
of clear consensus that this treatment is indicated. There
is ongoing debate as to whether atypical meningiomas
should receive radiotherapy or whether this treatment
should be limited to incompletely resected cases.1,12
Because of their aggressive behavior, atypical meningiomas have an unpredictable outcome, and reported
series have included only a few patients.25,34,50 Even after
GTR, tumor recurrence has been observed after several
years in some 20%–30% of cases.20,44 Thus, a reasonable
organized therapeutic strategy could be applied if recurrence could be predicted from surgical specimens, and for
this reason many authors have investigated the histological indices of proliferative and apoptotic potential in resected tumors, such as bcl-2,3,21 proliferating cell nuclear
antigen,3 and Ki 67 cell cycle–specific nuclear antigen.17,24
From these indices, researchers have attempted to establish the nature of the relationship between histological
aggressiveness and the recurrence of these meningiomas.
The molecular mechanisms underlying the development and progression of meningiomas remain poorly understood. Nevertheless, alterations in the pathways that
regulate cell proliferation must be involved. One of the
most important of these is the p16INK4A (p16)–cyclin-dependent kinase (CDK)–phosphorylated retinoblastoma
(pRB) pathway, which is altered in more than 80% of human cancers.9,48 The p16 coding gene has been found to be
homozygously deleted, mutated, or transcriptionally inhibited by methylation in a large number of different human tumor types.31,32,41 Mice lacking p16 are tumor prone
and develop multiple types of cancer, particularly after
exposure to carcinogens.23,42 Furthermore, RB is functionally inactivated in a range of cancers, either directly by
mutations or indirectly through altered expression and/or
activity of upstream regulators.13 As stated above, several
studies have focused on the role of cell cycle regulators
in various types of cancer progression and development.
However, cell cycle regulators have not yet been evaluated in meningioma, especially the atypical subtype.
In the present study, by immunohistochemically
analyzing tumor samples obtained during resection, we
aimed to determine the prognostic value of certain cell
cycle regulators (CDK4, CDK6, p16, p15, p21, p27, pRB
protein, and cyclin D1) in predicting the recurrence of
atypical meningioma after resection. We also estimated
1190
the number of mitoses as well as the immunoreactivity
of MIB-1 antigen and p53, which are already known to
be proliferative markers for predicting the recurrence of
meningioma. In addition, we examined other factors predisposing atypical meningioma to recurrence.
Methods
Patient Collection
The study protocol was approved by the institutional review boards of Samsung Changwon Hospital
and Dong-A University Medical Center, and all patients
or their families provided written informed consent. We
conducted a retrospective case study and clinical review
of the 353 meningioma patients who had been surgically
treated by Drs. K. H. Kim and Y. Z. Kim at the Samsung
Changwon Hospital and by Dr. H. D. Kim at Dong-A University Medical Center in the period from January 2000
to June 2012. All patients had undergone radical surgery
and had a tumor sample for histopathological diagnosis.
Among these cases, we selected the tumors that met the
diagnostic criteria for atypical meningioma, as outlined
in the 2007 WHO classification.38
The following patients were excluded: 1) those
with recurrent atypical meningioma after treatment for
a previous benign meningioma; 2) those with multiple
intracranial meningiomas, because of the difficulty in
evaluating treatment response; 3) those with spinal cord
meningioma; 4) those who had undergone preoperative
radiotherapy for tumor; and 5) those with ≤ 6 months of
follow-up due to follow-up loss.
Patient sex, age at the time of surgery, symptoms at
diagnosis, tumor location and size, extent of resection,
histological grade, use of postoperative radiotherapy, duration of follow-up, and recurrence were retrospectively
reviewed for each patient by using the medical records.
Neuroradiological Findings of Atypical Meningiomas
Tumor size was defined as the largest tumor diameter
rounded to the nearest centimeter on Gd-enhanced T1weighted MR images before the initial surgery. Peritumoral edema was estimated by the longest distance from
the margin of the tumor on FLAIR images. The locations
of tumors were divided into convexity and nonconvexity
groups. The extent of resection was categorized as either
complete or incomplete. Complete resection was defined
as Simpson Grade I or II, and incomplete resection was
defined as Simpson Grade III–V. The extent of resection
was estimated not only during the operation itself but also
on MRI, which was performed immediately after surgery.
Recurrence was defined as the presence of new tumor in
patients with a completely resected tumor, as judged on
the first postoperative MR image, or as evidence of new
growth of an incompletely resected tumor on serial postoperative MR images compared with the immediate postoperative MR images.
All patients had undergone preoperative MRI. Baseline postoperative MRI was performed immediately after surgery to evaluate the residual mass and then at 3- or
6-month intervals within the first 2 years. To assess tumor
J Neurosurg / Volume 121 / November 2014
Cell cycle regulators for atypical meningioma
recurrence, serial MRI was performed at 1- to 2-year intervals in asymptomatic patients, but if mass-related symptoms or focal neurological signs developed, MRI was performed immediately. Three neuroradiologists individually
conducted radiological reviews to characterize tumors and
to determine the presence of a recurrence without any clinical or pathological information on the patients.
Therapeutic Strategies for Atypical Meningioma
Surgical indications for meningioma were as follows:
1) tumor producing neurological symptoms, 2) growing tumor observed during regular follow-up, 3) tumor
with a size of 3 cm or more, and 4) tumor requiring a
differential diagnosis from other malignancies. Patients
with completely resected atypical meningiomas who
do not receive radiation therapy are closely observed at
our institutions. We recommend postoperative radiation
therapy in all patients with atypical meningiomas that are
not completely resected. At the same time, as we have already mentioned, although postoperative radiotherapy is
commonly applied for the remnant atypical meningioma,
strong agreement for this course of action has not been
established. In cases of recurrent meningiomas, reoperation should be considered as the first choice. Gamma
Knife radiosurgery is an alternative treatment modality
for small or surgically inaccessible meningiomas and in
patients of advanced age or with a high operative risk. Patients who underwent incomplete resection of the tumor
were treated with 3D conformal radiotherapy. Total irradiation dose ranged from 50 to 60 Gy (2 Gy per fraction a
day, 5 fractions a week), depending on the decision of the
radiation oncologist.
Immunohistochemical Staining
All tissue specimens were examined for cell-cycle
regulatory proteins (p16, p15, p21, p27, CDK4, CDK6,
pRB protein, and cyclin D1) and proliferative markers
(MIB-1 antigen, mitosis, and p53). For this analysis, the
labeled streptavidin-biotin method was performed on
sections from paraffin-embedded tissues that had been
used for pathological diagnoses. The following monoclonal or polyclonal primary antibodies were used: p16
(1:100, Neomark), p15 (1:100, Dako), p21 (1:100, Neomark), p27 (1:100, Neomark), CDK4 (1:100, Santa Cruz),
CDK6 (1:100, Santa Cruz), pRB (1:75, Life Technology),
cyclin D1 (1:100, Neomark), MIB-1 antigen (1:100, Immunotech), and p53 (1:100 Neomark).
Analysis and Interpretation of Immunoreactivity
Appropriate positive and negative controls were used
throughout the study. Negative controls were obtained by
omitting the primary antibody. Sections from normal meninges obtained from autopsy specimens were used as the
positive control for p16, p15, p21, p27, CDK4 and 6, pRB
protein, and cyclin D1. Ten fields were selected from the
regions with the highest concentrations of immunopositive nuclei and examined at high power magnification
(×400). Each field corresponded to a total number of cells
ranging from 700 to 1000 in relation to the cellularity of
the tumor specimen. Areas of necrosis, normal meningeal
J Neurosurg / Volume 121 / November 2014
cells, and endothelial cells were excluded from the evaluation. On considering 1000 cells by manual counting, the
immunoreactivity of proteins and markers was described
as the percentage of immunopositive cells. Mitoses were
counted on slides stained with H & E. The mitotic index
was defined as the number of mitoses per 10 hpf. Two
different neuropathologists (E. H. Lee and D. C. Kim),
who were blinded to patient clinical and radiological information, reviewed all slides. There was only one discordant case (1.5%) in both reviews of immunoreactivity,
and its immunoreactivity was determined after discussion. Digital images were captured using a microscope
(model BX41TF, Olympus) and digital camera (model
DP70, Olympus).
The purpose of analyzing the immunoreactivity of
cell cycle regulators and proliferative markers was to
determine whether these markers have an effect on the
recurrence of atypical meningiomas. Therefore, we performed receiver operating characteristic (ROC) curve
analysis on the immunoreactivity of the cell-cycle regulatory proteins and proliferative markers to predict the
likelihood of recurrence.11 We tried to determine the
threshold of immunoreactivity to the highest possible
sensitivity and specificity. Through sensitivity-specificity
analysis, the cutoff value (the point at which sensitivity
and specificity cross) was determined for each marker,
as correlated with recurrence (Table 1). In fact, in the autopsy specimen, all of the cell-cycle regulatory proteins
and proliferative markers were immunohistochemically
stained below the cutoff value that we had determined.
Therefore, based on the cutoff value for the immunoreactivity of each marker, sequential correlation analysis with
the recurrence of atypical meningioma was performed.
Statistical Analysis
Differences between subgroups were analyzed using
the Student t-test for normally distributed continuous values and the Mann-Whitney U-test for nonnormally distributed continuous values. The chi-square test was used
to analyze categorical variables. To define the cutoff value, the performance of each cell-cycle regulatory protein
and proliferative marker as a prognostic factor for the recurrence of atypical meningioma was investigated using
ROC curve analysis and sensitivity-specificity analysis.
Recurrence-free survival (RFS) was calculated according
to the Kaplan-Meier method, and comparisons between
groups were performed using log-rank tests. Variables
found to be significantly associated with the recurrence
of atypical meningiomas in the univariate analyses were
then subjected to multivariate analyses. Moreover, several additional variables that have been associated with
the recurrence of atypical meningioma in the literature
and that we have been interested in were also subjected
to multivariate analysis. In the multivariate analysis, the
Cox proportional-hazards regression model was used to
assess the independent effects of specific factors on the
tumor recurrence rate and to define the hazard ratios for
significant covariates. Two-sided p values below 0.05
were considered statistically significant. SPSS version
12.0 (SPSS Inc.) was used for the statistical analysis.
1191
M. S. Kim et al.
TABLE 1: Results of ROC curve analysis, sensitivity-specificity analysis, and determination of cutoff values*
Marker
cell-cycle regulatory protein
p16
p15
p21
p27
CDK4
CDK6
pRB
cyclin D1
proliferative marker
MIB-1 antigen
mitosis (/10 hpf)
p53
Mean % of IHC
Staining Nuclei†
AUC
Cutoff Value
Sensitivity
Specificity
24.73 ± 5.36
69.50 ± 9.24
11.32 ± 3.02
41.89 ± 10.83
27.66 ± 5.49
15.37 ± 4.71
23.45 ± 3.88
44.64 ± 12.03
0.682
0.708
0.823
0.694
0.819
0.667
0.731
0.716
27%
73%
13%
43%
30%
17%
25%
48%
60.3
58.9
71.7
90.8
73.8
55.7
68.2
63.5
72.4
84.5
75.3
75.8
80.4
76.1
73.3
73.7
4.74 ± 1.91
6.92 ± 2.48
17.35 ± 4.65
0.882
0.835
0.720
6%
8
20%
73.0
69.9
63.1
86.2
81.4
76.9
* AUC = area under the ROC curve; CDK = cyclin-dependent kinase; IHC = immunohistochemical.
† Values expressed as mean ± standard error.
Results
Patient and Tumor Characteristics
From a total of 353 meningioma cases in the defined
study period, 67 atypical meningioma patients (39 female, 28 male) were eligible for our analysis. The mean
age at diagnosis for these patients was 56.6 years (range
26.4–87.2 years). Sixty-three of the patients (94.0%) had
clinical symptoms before diagnosis. The most frequent
chief complaints at presentation were headache (33 cases
[49.3%]), seizures (13 cases [19.4%]), focal neurological
deficit such as motor weakness and dysphasia (11 cases
[16.4%]), and altered mentation (6 cases [9.0%]; Table 2).
Twenty-nine tumors (43.3%) were located in the
convexity regions and 38 (56.7%) in the nonconvexity regions. The mean maximal tumor diameter was 4.38 cm
(range 2.45–8.32 cm), and the mean extent of peritumoral
edema was 2.05 cm (range 0.00–5.54 cm).
All 67 patients had undergone radical resection of
the tumor. Complete resection was achieved in 36 patients (53.7%), and incomplete resection in 31 patients
(46.3%). The patients with complete resection received no
postoperative radiotherapy. Nineteen patients (61.3%) received radiotherapy following an incomplete resection (9
[50.0%] of 18 with Simpson Grade III tumors, 8 [72.7%]
of 11 with Simpson Grade IV tumors, and 2 [100%] of
2 with Simpson Grade V tumors). The other 12 patients
(38.7%) with incomplete resection refused the postoperative radiotherapy.
Results of Immunohistochemical Staining
In terms of cell-cycle regulatory proteins, p16 was
immunohistochemically overstained above the cutoff value in 44 samples (65.7%), p15 in 21 samples (31.3%), p21
in 25 samples (37.3%), p27 in 32 samples (47.8%), CDK4
1192
in 38 samples (56.7%), CDK6 in 26 samples (38.8%),
pRB protein in 42 samples (62.7%), and cyclin D1 in 49
samples (73.1%). In terms of the proliferative markers,
immunohistochemical overstaining for MIB-1 antigen
was found in 33 samples (49.3%), increased mitosis in 31
samples (46.3%), and immunohistochemical overstaining
for p53 in 29 samples (43.30%; Table 2).
Recurrences
The mean follow-up time from the date of resection
was 47.7 months (range 8.4–132.1 months). During follow-up, 26 patients (38.8%) presented with recurrence, all
cases occurring more than 1 year postsurgery. The mean
time to recurrence was 61.8 months (range 15.6–111.1
months). The actual 5- and 10-year RFSs were 67.8% and
28.3%, respectively. All recurrences occurred at the original site of surgery, and there was no distant metastasis
extracranially.
In terms of the clinical and radiological characteristics, recurrence occurred in 15 (39.5%) of the 38 patients
who were 60 years of age or younger, 13 (46.4%) of the
28 male patients, 16 (42.1%) of the 38 patients whose tumor had a nonconvexity location, 12 (46.2%) of the 26
patients who had a tumor size ≥ 5 cm, 10 (47.6%) of the
21 patients who had a tumor with peritumoral edema ≥ 3
cm, 19 (61.3%) of the 31 patients who underwent incomplete resection, and 22 (45.8%) of the 48 patients who did
not receive postoperative radiotherapy (Table 3). Among
these characteristics, there was a statistically significant
difference in the recurrence rate according to the extent
of resection and the presence of postoperative radiotherapy (p < 0.001 and p = 0.042, respectively, chi-square
test). There was also a statistically significant difference
in the time to recurrence according to the extent of resection and postoperative radiotherapy (p = 0.001 and p =
0.022, respectively, Mann-Whitney U-test). Kaplan-Meier
J Neurosurg / Volume 121 / November 2014
Cell cycle regulators for atypical meningioma
TABLE 2: Clinicoradiological characteristics and results of
immunohistochemical overstaining for markers in 67 atypical
meningiomas*
Variable
Value
mean age in yrs (range)
male/female
chief complaint
headache
seizure
focal neurological deficit
altered mentation
no clinical symptom
tumor location
convexity
nonconvexity
mean maximal diameter in cm (range)
mean size of peritumoral edema in cm (range)
extent of resection
complete resection
incomplete resection
postop RT
yes
no
IHC overstaining
p16 (≥27%)
p15 (≥73%)
p21 (≥13%)
p27 (≥43%)
CDK4 (≥30%)
CDK6 (≥17 %)
pRB (≥25%)
cyclin D1 (≥48%)
MIB-1 antigen (≥6%)
mitosis (≥8/10 hpf)
p53 (≥20%)
56.6 (26.4–87.2)
28/39
33 (49.3%)
13 (19.4%)
11 (16.4%)
6 (9.0%)
4 (6.0%)
29 (43.3%)
38 (56.7%)
4.38 (2.45–8.32)
2.05 (0.00–5.54)
36 (53.7%)
31 (46.3%)
19 (28.4%)
12 (17.9%)
44 (65.7%)
21 (31.3%)
25 (37.3%)
32 (47.8%)
38 (56.7%)
26 (38.8%)
42 (62.7%)
49 (73.1%)
33 (49.3%)
31 (46.3%)
29 (43.3%)
* RT = radiotherapy.
survival analysis for RFS also showed statistically significant differences in the extent of resection (complete vs
incomplete: p = 0.002, log-rank test; Fig. 1A) and postoperative radiotherapy (yes vs no: p = 0.022, log-rank test).
In terms of cell-cycle regulatory protein, a statistically significant, higher recurrence rate was found (chisquare test) in immunohistochemical understaining for
p16 (p = 0.004), overstaining for CDK6 (p = 0.013), and
overstaining for pRB protein (p < 0.001). Likewise, there
was also a statistically shorter time to recurrence in immunohistochemical understaining for p16 (p < 0.001),
overstaining for CDK6 (p < 0.001), and overstaining for
pRB protein (p = 0.002), using the Mann-Whitney U-test
(Table 3). Kaplan-Meier survival analysis for RFS also
showed statistically significant differences in immunohistochemical overstaining versus understaining for p16
J Neurosurg / Volume 121 / November 2014
(p < 0.001, log-rank test), CDK6 (p < 0.001, log-rank test),
and pRB protein (p = 0.001, log-rank test; Fig. 1B–D).
All proliferative markers showed that immunohistochemical overstaining had a statistically higher recurrence rate (p < 0.05, chi-square test) and a shorter time
to recurrence (p < 0.05, Mann-Whitney U-test; Table 3).
Kaplan-Meier survival analysis for RFS also showed statistically significant differences in immunohistochemical
overstaining versus understaining for MIB-1 antigen (p =
0.007, log-rank test) and p53 protein (p = 0.021, log-rank
test) and in the mitotic index (p = 0.013, log-rank test).
Univariate Analysis of Factors Predicting Recurrence of
Atypical Meningioma
In terms of the clinical characteristics, incomplete
resection (p < 0.001) and the lack of postoperative radiotherapy (p = 0.030) were both associated with recurrence
(Table 4). For the cell-cycle regulatory proteins, univariate analysis showed that immunohistochemical understaining for p16 (p < 0.001) and p21 (p = 0.039) were associated with tumor recurrence. Immunohistochemical
overstaining for CDK4 (p = 0.033), CDK6 (p = 0.048),
pRB protein (p < 0.001), and cyclin D1 (p = 0.035) were
also directly associated with recurrence. In terms of proliferative markers, analysis showed that immunohistochemical overstaining for MIB-1 antigen (p = 0.019), the
mitotic index (p = 0.022), and p53 (p = 0.041) were associated with recurrence.
Multivariate Analysis of Factors Predicting Recurrence of
Atypical Meningioma
Multivariate analysis showed that the following factors were independently associated with a higher rate of
recurrence: incomplete resection (HR 4.513, p < 0.001;
Table 5); immunohistochemical understaining for p16
(HR 3.214, p < 0.001); immunohistochemical overstaining for CDK6 (HR 3.427, p < 0.001), pRB protein (HR
2.854, p = 0.008), and p53 (HR 2.296, p = 0.040); and increased MIB-1 antigen (HR 2.665, p = 0.013) and number
of mitoses (≥ 8/10 hpf; HR 2.438, p = 0.024).
The factors associated with recurrence in the univariate analysis but not independently associated with a
higher rate of recurrence in the multivariate analysis were
as follows: no postoperative radiotherapy (p = 0.058); immunohistochemical understaining for p21 (p = 0.054),
immunohistochemical overstaining for CDK4 (p = 0.112),
and immunohistochemical overstaining for cyclin D1 (p
= 0.274). Other factors of interest, such as p15 (p = 0.157)
and p27 (p = 0.326), were not associated on multivariate
analysis (Table 5).
Discussion
The purpose of this study was to evaluate the role of
cell-cycle regulatory proteins in the recurrence of atypical meningiomas using immunohistochemical staining
analysis. To the best of our knowledge, the present study
is the largest work of clinical research to use immunohistochemical staining to assess the role of cell-cycle regulatory proteins in the recurrence of atypical meningiomas.
1193
M. S. Kim et al.
Fig. 1. Recurrence-free survival curves for the patients with atypical meningiomas. A: Complete resection versus incomplete resection. B: Immunohistochemical understaining (< 27%) versus overstaining ( ≥ 27%) for p16. C: Immunohistochemical understaining (< 17%) versus overstaining (≥ 17%) for CDK6. D: Immunohistochemical understaining (< 25%) versus overstaining (≥ 25%) for pRB protein.
Although there was a study showing that p16, CDK6, and
pRB were differentially expressed in meningioma cell
cultures with a 20-, 30-, and 36-fold difference between
the lowest and highest levels of each protein, respectively,
that work did not suggest any clinical association.2
Interestingly, this study showed that immunohistochemical staining results for some cell-cycle regulatory
proteins (p16, CDK6, pRB) predict the recurrence of atypical meningiomas. In fact, the protein p16 has been noted
with regard to potential new prognostic markers for meningiomas. It is encoded by the tumor suppressor gene CDKN2A and is a CDK inhibitor involved in cell cycle arrest
via p53-independent mechanisms. One of the mechanisms
held responsible for malignant progression in meningiomas
is the loss of chromosome 9p, which harbors CDKN2A.
Recent publications have reported high frequencies of genetic and epigenetic aberrations of p16 in meningiomas.36,47
CDKN2A deletions have been particularly observed in malignant meningiomas and have been correlated with short1194
ened survival.5,36,43 On the other hand, Barker et al.4 were
unable to demonstrate p16 loss in their meningioma cases.
Results of the only other immunohistochemical study on
p16 in meningiomas are in line with the theory of malignant progression and CDKN2A loss, as the data indicated
high p16 positivity in benign forms and those without recurrence.22 However, there is a report suggesting a result in
opposition to ours in terms of the expression of p16: Terzi
et al.46 reported that Ki 67 and p53 labeling indices as well
as overexpression of p16 were strongly associated with decreased RFS in a univariate analysis. In their study, the fact
that immunohistochemical overexpression of Ki 67 and
p53 were factors predicting meningioma recurrence agrees
with our results, whereas their finding that the immunohistochemical overexpression of p16 predicts recurrence in
meningiomas directly opposes our results. Note, however,
that their immunohistochemical analysis was focused on
histological grading of the meningioma, and thus benign,
atypical, and malignant meningiomas were all included in
J Neurosurg / Volume 121 / November 2014
Cell cycle regulators for atypical meningioma
TABLE 3: Time to recurrence in 67 patients with atypical meningioma, according to the clinicoradiological
characteristics and results of immunohistochemical staining for markers
Variable
No. of Reccurences (%)
Mean Time to Recurrence (mos)*
p Value†
15/38 (39.5)
11/29 (37.9)
57.9 ± 11.7
67.2 ± 13.4
0.889
13/28 (46.4)
13/39 (33.3)
56.3 ± 10.3
67.4 ± 12.0
0.475
10/29 (34.5)
16/38 (42.1)
63.4 ± 10.5
60.0 ± 10.2
0.548
14/41 (34.1)
12/26 (46.2)
72.9 ± 13.2
64.5 ± 9.9
0.462
16/46 (34.8)
10/21 (47.6)
59.8 ± 8.7
65.1 ± 10.2
0.617
7/36 (19.4)
19/31 (61.3)
91.3 ± 15.0
45.1 ± 17.3
<0.001
4/19 (21.1)
22/48 (45.8)
78.1 ± 12.8
50.8 ± 11.2
0.022
7/44 (15.9)
19/23 (82.6)
85.3 ± 6.6
35.5 ± 5.5
<0.001
6/21 (28.6)
20/46 (43.5)
74.0 ± 10.4
55.1 ± 5.1
0.192
6/25 (24.0)
20/42 (47.6)
75.9 ± 9.4
52.5 ± 5.4
0.079
10/32 (31.3)
16/35 (45.7)
68.7 ± 8.1
53.4 ± 6.2
0.201
19/38 (50.0)
7/29 (24.1)
53.9 ± 6.2
68.6 ± 7.7
0.103
14/26 (53.8)
12/41 (29.3)
33.8 ± 5.1
75.3 ± 6.3
<0.001
24/42 (57.1)
2/25 (8.0)
47.6 ± 5.2
94.5 ± 7.3
0.002
22/49 (44.9)
4/18 (22.2)
56.1 ± 5.1
78.5 ± 11.2
0.283
19/34 (55.9)
7/33 (21.2)
44.8 ± 4.9
79.8 ± 7.8
0.007
age in yrs
≤60
>60
sex
male
female
location
convexity
nonconvexity
max tumor diameter in cm
<5
≥5
peritumoral edema in cm
<3
≥3
complete resection
yes
no
postop RT
yes
no
IHC staining for p16
≥27%
<27%
IHC staining for p15
≥73%
<73%
IHC staining for p21
≥13%
<13%
IHC staining for p27
≥43%
<43%
IHC staining for CDK4
≥30%
<30%
IHC staining for CDK6
≥17%
<17%
IHC staining for pRB
≥25%
<25%
IHC staining for cyclin D1
≥48%
<48%
IHC staining for MIB-1 antigen
≥6%
<6%
(continued)
J Neurosurg / Volume 121 / November 2014
1195
M. S. Kim et al.
TABLE 3: Time to recurrence in 67 patients with atypical meningioma, according to the clinicoradiological
characteristics and results of immunohistochemical staining for markers (continued)
Variable
No. of Reccurences (%)
Mean Time to Recurrence (mos)*
p Value†
18/31 (58.1)
8/36 (22.2)
45.3 ± 5.3
76.4 ± 7.7
0.015
16/30 (53.3)
10/37 (27.0)
46.2 ± 6.1
75.0 ± 7.4
0.034
proportion of mitotic cells
≥8/10 hpf
<8/10 hpf
IHC staining for p53
≥20%
<20%
* Values expressed as mean ± standard error.
† Mann-Whitney U-test. Boldface type indicates a statistically significant value.
In fact, the prognostic role of cell-cycle regulatory
proteins and proliferative markers has been established
for several cancer types. In particular, several studies
have documented the role of RB protein in the prognosis
and progression of malignant brain tumors such as glioblastoma.7,14,16 Among these works, the study by Hilton
et al.16 suggested that glioblastomas showing widespread
immunohistochemical expression of RB protein have a
better prognosis than those without this feature, which is
different from our results. However, the authors did not
their study. Furthermore, their cutoff value for the overexpression of p16 was 10%, which was different from our
cutoff of 27%. Additionally, they did not exclude cytoplasmic staining of p16. Because it is a CDK inhibitor, p16 is
presumed to function in the nucleus, which is where it is
located in normal cells. Cytoplasmic staining is therefore
considered nonspecific or controversial. In our study, only
nuclear staining for p16 was considered. Therefore, it is
impossible for us to make a direct comparison with our
results.
TABLE 4: Univariate analysis of factors predicting recurrence among 67 atypical meningiomas after resection, Cox
proportional-hazards regression analysis
Recurrence
Variable
no. of cases
clinical characteristic
age >60 yrs
male sex
nonconvexity location
max tumor diameter ≥5 cm
peritumoral edema ≥3 cm
incomplete resection
no postop RT
immunohistochemical staining for markers
p16†
p15‡
p21†
p27‡
CDK4‡
CDK6‡
pRB protein‡
cyclin D1‡
MIB-1 antigen‡
no. of mitoses‡
p53‡
Yes
Univariate Analysis
No
HR
95% CI
p Value*
26
41
11 (42.3%)
13 (50.0%)
16 (61.5%)
12 (46.2%)
10 (38.5%)
19 (73.1%)
22 (84.6%)
18 (43.9%)
26 (63.4%)
22 (53.7%)
14 (34.1%)
11 (26.9%)
12 (29.3%)
26 (63.4%)
1.279
1.389
1.221
1.352
1.369
6.055
2.177
0.537–2.021
0.642–2.136
0.473–1.969
0.664–2.041
0.708–2.029
3.417–8.663
1.466–2.888
0.836
0.708
0.879
0.724
0.713
<0.001
0.030
7 (26.9%)
6 (23.1%)
6 (23.1%)
10 (38.5%)
19 (73.1%)
14 (53.8%)
24 (92.3%)
22 (84.6%)
19 (73.1%)
18 (69.2%)
16 (61.5%)
37 (90.2%)
15 (36.6%)
19 (46.3%)
22 (53.7%)
19 (46.3%)
12 (29.3%)
18 (43.9%)
27 (65.9%)
15 (36.6%)
13 (31.7%)
14 (34.1%)
0.312
0.657
0.504
0.684
2.071
1.839
7.142
2.020
2.634
2.613
1.973
0.117–0.507
0.756–1.301
0.382–0.896
0.705–1.421
1.429–2.713
1.179–2.499
5.362–8.922
1.298–2.742
1.535–3.733
1.477–3.749
1.295–2.651
<0.001
0.424
0.039
0.572
0.033
0.048
<0.001
0.035
0.019
0.022
0.041
* Boldface type indicates a statistically significant value.
† Understaining.
‡ Overstaining.
1196
J Neurosurg / Volume 121 / November 2014
Cell cycle regulators for atypical meningioma
TABLE 5: Multivariate analysis of predisposing factors for recurrence of atypical meningioma, Cox
proportional-hazards regression analysis
Variable
HR
95% CI
p Value*
extent of resection (incomplete vs complete)
postop RT (no vs yes)
IHC staining for p16 (<27% vs ≥27%)
IHC staining for p15 (<73% vs ≥73%)
IHC staining for p21 (<13% vs ≥13%)
IHC staining for p27 (<43% vs ≥43%)
IHC staining for CDK4 (≥30% vs <30%)
IHC staining for CDK6 (≥17% vs <17%)
IHC staining for pRB protein (≥25% vs <25%)
IHC staining for cyclin D1 (≥48% vs <48%)
MIB-1 index (≥6% vs <6%)
mitotic number (≥8 vs <8)
IHC staining for p53 (≥20% vs <20%)
4.513
2.106
3.214
1.783
2.143
1.415
1.988
3.427
2.854
1.628
2.665
2.438
2.296
2.872–6.154
0.981–3.231
2.012–4.416
0.934–2.632
0.972–3.004
0.859–1.971
0.981–2.995
2.437–4.417
1.839–3.869
0.839–2.417
1.425–3.905
1.273–3.603
1.194–3.398
<0.001
0.058
<0.001
0.157
0.054
0.326
0.112
<0.001
0.008
0.274
0.013
0.024
0.040
* Boldface type indicates a statistically significant value.
separate RB protein into phosphorylated and unphosphorylated forms. Thus, the data from unphosphorylated
RB proteins were intermingled with those from pRB proteins, which accounts for the different results. As mentioned earlier, pRB protein is important for transit into
the S phase in the cell cycle. Therefore, interpretation of
their results is limited.
Clinically, recurrence rates vary between studies, depending on both the duration of follow-up and the number
of patients studied. An analysis of some of these studies
has shown that the patient’s age at diagnosis,20 complete
resection or GTR,30 and postoperative radiotherapy20,33
are invariably associated with lower risks of atypical meningioma recurrence.
As regards the extent of resection, which is a significant independent predictive factor of recurrence in
atypical meningiomas as well as in meningiomas overall, many authors have reported similar results. The RFS
rates have been reported as 62%–93% at 5 years after
GTR and 25%–63% after subtotal resection.15,18,28 Results
in the present study—those obtained through KaplanMeier survival analysis and the Cox proportional-hazards
regression model—correspond well with these findings,
suggesting that the most important factor in determining
the likelihood of meningioma recurrence is the extent of
tumor resection.
In this study, postoperative radiotherapy was not an
independent factor predicting the recurrence of atypical
meningiomas in the multivariate analysis (Cox proportional-hazards regression model), and it showed only a
tendency to predict a recurrence (p = 0.058). However,
statistically significant, lower recurrence rates (chi-square
test) and a longer time to recurrence (Mann-Whitney Utest and log-rank test) were found in the atypical meningioma patients who had received postoperative radiotherapy. In fact, many authors advocate adjuvant radiotherapy
for the treatment of malignant meningiomas regardless of
the extent of resection because of the extremely high rate
J Neurosurg / Volume 121 / November 2014
of local recurrence.10,40 However, the optimal treatment
for atypical meningiomas is still controversial. Atypical
meningiomas are rare tumors often integrated with benign or malignant histologies when analysis is performed.
A few studies have reported the outcomes and prognostic
factors for solitary atypical meningiomas, but the results
are inconsistent.1,20,26 Some investigators favor the early
addition of postoperative radiotherapy even after GTR to
achieve better local control.1,20 Others argue that the role
of postoperative radiotherapy remains unclear.26,44 Therefore, more data are essential to establish the optimum
postoperative treatment in patients with atypical meningioma. Despite inconsistent reports regarding the benefit
of postoperative radiotherapy in atypical meningioma, a
combined treatment approach using resection followed by
postoperative radiotherapy has been commonly applied
given this tumor type’s high recurrence rate and poor
prognosis. As shown in our results, the completeness of
resection is a well-known prognosticator of the local recurrence of high-risk meningiomas.
Despite the contributions this study makes to the literature, it has several limitations. First, its main limitation
is the inherent bias introduced by its retrospective nature.
Indeed, it is difficult to provide sufficient statistical power
from such a small number of patients (26) with a recurrence to prove reliable results. We attempted to reduce this
bias by collecting patient data from complete medical and
radiological records and by recruiting patients who had
been treated using the same protocol. Although the pathological slides and radiological images were independently
reviewed by multiple investigators, without any information on the patients to reduce the bias, we cannot say clearly
that no bias originated from this retrospective study. Thus,
to improve this weakness, the conclusions drawn from our
data need further validation through prospective and randomized clinical trials in a larger number of cases.
Second, we analyzed the cell cycle regulators only at
the protein level by using immunohistochemical staining.
1197
M. S. Kim et al.
Although the molecular and genetic alterations underlying the progression of meningiomas are still poorly understood, cytogenetic studies have indicated that atypical
and anaplastic meningiomas frequently show complex numerical and structural aberrations involving several chromosomes associated with cell cycle regulators. Therefore,
given our limited focus on cell-cycle regulatory proteins,
our study cannot explain all the mechanisms in the genetic and molecular biological processes involved.
Third, we did not deal with neurofibromatosis in
these meningiomas. However, accompanying conditions,
such as neurofibromatosis Type 2 (NF2), can also contribute to prognosis. Patients with NF2 are known to have
meningiomas at a relatively younger age and an increased
chance of multicentricity, findings that have been confirmed by subsequent research.46 Moreover, a higher incidence of NF2 has been reported in patients with WHO
Grade II and III meningiomas.37 Perry et al. also noted a
higher incidence of atypical and malignant meningiomas
in patients with NF2. Another interesting finding from
the Perry study was the greater loss of p16 in patients with
NF; that is, 70% of NF cases showed p16 loss. Nevertheless, we did not exclude the possibility of interference by
NF2 in our cases.
The fourth limitation is that we did not examine all
the cell-cycle regulatory proteins that may be implicated.
The cell-cycle control system is a cyclical biochemical
device constructed from a set of interacting proteins that
induce and coordinate proper progression through the
cycle, and includes the cyclins, CDKs, and their CDK inhibitors. However, we studied a specific aspect of the cellcycle control system, especially the transmission from G1
to the S phase. This may have biased the interpretation of
our results, because some interactions between regulatory
proteins were not considered.
Finally, despite the interpretation of sample immunoreactivity by two different neuropathologists, we are
unsure if the results are absolutely correct because the
interpretation of many immunohistochemical stains is
qualitative and subjective. Proper interpretation of most
immunohistochemical stains depends to some extent
on estimating antigen content and in establishing cutoff
levels between positive and negative results. Reasonable
reproducibility from run to run is essential for these cutoff levels to work. Additionally, threshold levels require
adjustment to methodology, in particular to method sensitivity. For this reason, we used specificity-sensitivity
testing to determine the optimal cutoff level. However, to
ensure reproducibility, additional studies are necessary.
Conclusions
In this study, we investigated the prognostic value
of several cell-cycle regulatory proteins in predicting the
recurrence of atypical meningiomas after resection. We
found that p16, CDK6, and pRB protein are associated
with the recurrence of atypical meningiomas. We also
confirmed that proliferative markers, such as the MIB-1
labeling index, mitotic index, and p53, have a significant
association with the recurrence of atypical meningiomas.
Additionally, incomplete resection was associated with a
1198
higher recurrence rate. Nonetheless, further studies using
sophisticated and systemically developed molecular biology techniques are required to examine this meningioma
subtype further, especially to characterize the genetic process underlying the recurrence of atypical meningiomas.
Acknowledgments
The authors thank Yun Gyu Song, M.D., and Ha Young Lee,
M.D. (Department of Radiology, Samsung Changwon Hospital),
and Sun Sup Choi, M.D. (Department of Radiology, Dong-A University Medical Center), for their review of the neuroradiological
images; Young Wook Kim, M.D. (Department of Biostatistics,
Samsung Changwon Hospital), for assistance with the statistical
analysis; Hyeon Wook Lee, M.D. (Department of Pathology, Samsung Changwon Hospital), and Dae Chul Kim, M.D. (Department
of Pathology, Dong-A University Medical Center), for performing
the immunohistochemical staining; and Young Min Choi, M.D.
(Department of Radiation Oncology, Dong-A University Medical
Center), for delivering the radiotherapy detailed in this work.
Disclosure
This study was financially supported by a Samsung Biomedical Research Institute grant (SMR-112171). The authors report no
conflict of interest concerning the materials or methods used in this
study or the findings specified in this paper.
Author contributions to the study and manuscript preparation
include the following. Conception and design: YZ Kim, MS Kim,
KH Kim. Acquisition of data: YZ Kim, MS Kim, EH Lee, YM Lee,
HD Kim. Analysis and interpretation of data: YZ Kim, MS Kim,
EH Lee, YM Lee, SH Lee. Drafting the article: YZ Kim, MS Kim.
Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the
manuscript on behalf of all authors: YZ Kim. Statistical analysis: YZ
Kim, MS Kim, SH Lee. Administrative/technical/material support:
YZ Kim, MS Kim, KH Kim, SH Lee, HD Kim. Study supervision:
YZ Kim.
References
1. Aghi MK, Carter BS, Cosgrove GR, Ojemann RG, AminHanjani S, Martuza RL, et al: Long-term recurrence rates of
atypical meningiomas after gross total resection with or without postoperative adjuvant radiation. Neurosurgery 64:56–
60, 2009
2. Al-Khalaf HH, Lach B, Allam A, Hassounah M, Alkhani A,
Elkum N, et al: Expression of survivin and p16INK4a/Cdk6/pRB
proteins and induction of apoptosis in response to radiation
and cisplatin in meningioma cells. Brain Res 1188:25–34,
2008
3. Alama A, Barbieri F, Spaziante R, Bruzzo C, Dadati P, Dorcaratto A, et al: Significance of cyclin D1 expression in meningiomas: a preliminary study. J Clin Neurosci 14:355–358,
2007
4. Barker FG, Chen P, Furman F, Aldape KD, Edwards MS, Israel MA: P16 deletion and mutation analysis in human brain
tumors. J Neurooncol 31:17–23, 1997
5. Boström J, Meyer-Puttlitz B, Wolter M, Blaschke B, Weber
RG, Lichter P, et al: Alterations of the tumor suppressor genes
CDKN2A (p16INK4a), p14ARF, CDKN2B (p15INK4b), and CDKN2C (p18INK4c) in atypical and anaplastic meningiomas. Am
J Pathol 159:661–669, 2001
6. Brat DJ, Parisi JE, Kleinschmidt-DeMasters BK, Yachnis AT,
Montine TJ, Boyer PJ, et al: Surgical neuropathology update: a
review of changes introduced by the WHO classification of tumours of the central nervous system. Arch Pathol Lab Med
132:993–1007, 2008
J Neurosurg / Volume 121 / November 2014
Cell cycle regulators for atypical meningioma
7. Cen L, Carlson BL, Schroeder MA, Ostrem JL, Kitange GJ,
Mladek AC, et al: p16-Cdk4-Rb axis controls sensitivity to a
cyclin-dependent kinase inhibitor PD0332991 in glioblastoma
xenograft cells. Neuro Oncol 14:870–881, 2012
8. Choy W, Kim W, Nagasawa D, Stramotas S, Yew A, Gopen
Q, et al: The molecular genetics and tumor pathogenesis of
meningiomas and the future directions of meningioma treatments. Neurosurg Focus 30(5):E6, 2011
9. Deshpande A, Sicinski P, Hinds PW: Cyclins and cdks in
development and cancer: a perspective. Oncogene 24:2909–
2915, 2005
10. Dziuk TW, Woo S, Butler EB, Thornby J, Grossman R, Dennis WS, et al: Malignant meningioma: an indication for initial
aggressive surgery and adjuvant radiotherapy. J Neurooncol
37:177–188, 1998
11. Eng J: Receiver operating characteristic analysis: a primer.
Acad Radiol 12:909–916, 2005
12. Engenhart-Cabillic R, Farhoud A, Sure U, Heinze S, Henzel
M, Mennel HD, et al: Clinicopathologic features of aggressive
meningioma emphasizing the role of radiotherapy in treatment. Strahlenther Onkol 182:641–646, 2006
13. Giacinti C, Giordano A: RB and cell cycle progression. Oncogene 25:5220–5227, 2006
14. Goldhoff P, Clarke J, Smirnov I, Berger MS, Prados MD,
James CD, et al: Clinical stratification of glioblastoma based
on alterations in retinoblastoma tumor suppressor protein
(RB1) and association with the proneural subtype. J Neuropathol Exp Neurol 71:83–89, 2012
15. Goyal LK, Suh JH, Mohan DS, Prayson RA, Lee J, Barnett
GH: Local control and overall survival in atypical meningioma: a retrospective study. Int J Radiat Oncol Biol Phys
46:57–61, 2000
16. Hilton DA, Penney M, Pobereskin L, Sanders H, Love S: Histological indicators of prognosis in glioblastomas: retinoblastoma
protein expression and oligodendroglial differentiation indicate
improved survival. Histopathology 44:555–560, 2004
17. Ho DM, Hsu CY, Ting LT, Chiang H: Histopathology and
MIB-1 labeling index predicted recurrence of meningiomas:
a proposal of diagnostic criteria for patients with atypical meningioma. Cancer 94:1538–1547, 2002
18. Jääskeläinen J, Haltia M, Servo A: Atypical and anaplastic
meningiomas: radiology, surgery, radiotherapy, and outcome.
Surg Neurol 25:233–242, 1986
19. Kane AJ, Sughrue ME, Rutkowski MJ, Shangari G, Fang S,
McDermott MW, et al: Anatomic location is a risk factor for
atypical and malignant meningiomas. Cancer 117:1272–
1278, 2011
20. Komotar RJ, Iorgulescu JB, Raper DM, Holland EC, Beal K,
Bilsky MH, et al: The role of radiotherapy following grosstotal resection of atypical meningiomas. Clinical article. J
Neurosurg 117:679–686, 2012
21. Konstantinidou AE, Pavlopoulos PM, Patsouris E, Kaklamanis L, Davaris P: Expression of apoptotic and proliferation
markers in meningiomas. J Pathol 186:325–330, 1998
22. Korshunov A, Shishkina L, Golanov A: Immunohistochemical analysis of p16INK4a, p14ARF, p18INK4c, p21CIP1,
p27KIP1 and p73 expression in 271 meningiomas correlation
with tumor grade and clinical outcome. Int J Cancer 104:
728–734, 2003
23. Krimpenfort P, Quon KC, Mooi WJ, Loonstra A, Berns A:
Loss of p16Ink4a confers susceptibility to metastatic melanoma in mice. Nature 413:83–86, 2001
24. Maes L, Lippens E, Kalala JP, de Ridder L: The hTERT-protein and Ki-67 labelling index in recurrent and non-recurrent
meningiomas. Cell Prolif 38:3–12, 2005
25. Maier H, Ofner D, Hittmair A, Kitz K, Budka H: Classic, atypical, and anaplastic meningioma: three histopathological subtypes of clinical relevance. J Neurosurg 77:616–623, 1992
J Neurosurg / Volume 121 / November 2014
26. Mair R, Morris K, Scott I, Carroll TA: Radiotherapy for atypical meningiomas. Clinical article. J Neurosurg 115:811–819,
2011
27. Marosi C, Hassler M, Roessler K, Reni M, Sant M, Mazza E, et
al: Meningioma. Crit Rev Oncol Hematol 67:153–171, 2008
28. Mirimanoff RO, Dosoretz DE, Linggood RM, Ojemann RG,
Martuza RL: Meningioma: analysis of recurrence and progression following neurosurgical resection. J Neurosurg 62:18–24,
1985
29. Modha A, Gutin PH: Diagnosis and treatment of atypical and
anaplastic meningiomas: a review. Neurosurgery 57:538–
550, 2005
30. Moon HS, Jung S, Jang WY, Jung TY, Moon KS, Kim IY:
Intracranial meningiomas, WHO Grade II: Prognostic implications of clinicopathologic features. J Korean Neurosurg
Soc 52:14–20, 2012
31. Nobori T, Miura K, Wu DJ, Lois A, Takabayashi K, Carson
DA: Deletions of the cyclin-dependent kinase-4 inhibitor gene
in multiple human cancers. Nature 368:753–756, 1994
32. Ortega S, Malumbres M, Barbacid M: Cyclin D-dependent
kinases, INK4 inhibitors and cancer. Biochim Biophys Acta
1602:73–87, 2002
33. Park HJ, Kang HC, Kim IH, Park SH, Kim DG, Park CK, et
al: The role of adjuvant radiotherapy in atypical meningioma.
J Neurooncol 115:241–247, 2013
34. Pasquier D, Bijmolt S, Veninga T, Rezvoy N, Villa S, Krengli
M, et al: Atypical and malignant meningioma: outcome and
prognostic factors in 119 irradiated patients. A multicenter,
retrospective study of the Rare Cancer Network. Int J Radiat
Oncol Biol Phys 71:1388–1393, 2008
35. Pearson BE, Markert JM, Fisher WS, Guthrie BL, Fiveash
JB, Palmer CA, et al: Hitting a moving target: evolution of a
treatment paradigm for atypical meningiomas amid changing
diagnostic criteria. Neurosurg Focus 24(5):E3, 2008
36. Perry A, Banerjee R, Lohse CM, Kleinschmidt-DeMasters BK,
Scheithauer BW: A role for chromosome 9p21 deletions in the
malignant progression of meningiomas and the prognosis of
anaplastic meningiomas. Brain Pathol 12:183–190, 2002
37. Perry A, Giannini C, Raghavan R, Scheithauer BW, Banerjee
R, Margraf L, et al: Aggressive phenotypic and genotypic features in pediatric and NF2-associated meningiomas: a clinicopathologic study of 53 cases. J Neuropathol Exp Neurol
60:994–1003, 2001
38. Perry A, Louis DN, Scheithauer BW, Budka H, von Diemling
A: Meningiomas, in Louis DN, Ohgaki H, Wiestler OD, et al
(eds): WHO Classification of Tumours of the Central Nervous System, ed 4. Lyon: IARC Press, 2007, pp 164–172
39. Rogers L, Gilbert M, Vogelbaum MA: Intracranial meningiomas of atypical (WHO grade II) histology. J Neurooncol
99:393–405, 2010
40. Rosenberg LA, Prayson RA, Lee J, Reddy C, Chao ST, Barnett
GH, et al: Long-term experience with World Health Organization grade III (malignant) meningiomas at a single institution.
Int J Radiat Oncol Biol Phys 74:427–432, 2009
41. Ruas M, Peters G: The p16INK4a/CDKN2A tumor suppressor and its relatives. Biochim Biophys Acta 1378:F115–F177,
1998
42. Sharpless NE, Bardeesy N, Lee KH, Carrasco D, Castrillon
DH, Aguirre AJ, et al: Loss of p16Ink4a with retention of
p19Arf predisposes mice to tumorigenesis. Nature 413:86–
91, 2001
43. Simon M, Park TW, Köster G, Mahlberg R, Hackenbroch M,
Boström J, et al: Alterations of INK4a(p16-p14ARF)/INK4b
(p15) expression and telomerase activation in meningioma
progression. J Neurooncol 55:149–158, 2001
44. Stessin AM, Schwartz A, Judanin G, Pannullo SC, Boockvar
JA, Schwartz TH, et al: Does adjuvant external-beam radiotherapy improve outcomes for nonbenign meningiomas? A
1199
M. S. Kim et al.
Surveillance, Epidemiology, and End Results (SEER)-based
analysis. Clinical article. J Neurosurg 117:669–675, 2012
45. Tanzler E, Morris CG, Kirwan JM, Amdur RJ, Mendenhall
WM: Outcomes of WHO Grade I meningiomas receiving
definitive or postoperative radiotherapy. Int J Radiat Oncol
Biol Phys 79:508–513, 2011
46. Terzi A, Saglam EA, Barak A, Soylemezoglu F: The significance of immunohistochemical expression of Ki-67, p53,
p21, and p16 in meningiomas tissue arrays. Pathol Res Pract
204:305–314, 2008
47. Tse JY, Ng HK, Lo KW, Chong EY, Lam PY, Ng EK, et al:
Analysis of cell cycle regulators: p16INK4A, pRb, and CDK4
in low- and high-grade meningiomas. Hum Pathol 29:1200–
1207, 1998
48. Vogelstein B, Kinzler KW: Cancer genes and the pathways
they control. Nat Med 10:789–799, 2004
49. Willis J, Smith C, Ironside JW, Erridge S, Whittle IR, Evering-
1200
ton D: The accuracy of meningioma grading: a 10-year retrospective audit. Neuropathol Appl Neurobiol 31:141–149, 2005
50. Yamasaki F, Yoshioka H, Hama S, Sugiyama K, Arita K, Kurisu
K: Recurrence of meningiomas. Cancer 89:1102–1110, 2000
Manuscript submitted December 2, 2013.
Accepted July 17, 2014.
Please include this information when citing this paper: published online August 22, 2014; DOI: 10.3171/2014.7.JNS132661.
Address correspondence to: Young Zoon Kim, M.D., Ph.D.,
Department of Neurosurgery and Division of Neurooncology, Samsung Changwon Hospital, Samsung Medical Center, Sungkyunkwan
University School of Medicine, 158 Paryong-ro, Masanhoewon-gu,
Changwon 630-723, Korea. email: [email protected].
J Neurosurg / Volume 121 / November 2014