Proliferative activity of acoustic neurilemomas without neurofibromatosis determined by monoclonal antibody MIB 1

The behavior of residual tumors following incomplete surgical resection for vestibular schwannomas

The management of vestibular schwannoma (VS) with residual tumor following incomplete resection remains controversial and little is known regarding postoperative tumor volume changes. The behavior of residual tumors was analyzed for 111 patients who underwent surgery for newly diagnosed VS between September 2006 and July 2017. The postoperative tumor volume changes were assessed during a mean follow-up of 69 months (range 36–147 months). Fifty-three patients underwent imaging surveillance following incomplete resection. There was no residual tumor growth in 44 patients (83%). A significant regression of residual tumor volume was noted in the no growth group at postoperative 1 year (p = 0.028), 2 years (p = 0.012), but not from 3 years onwards. Significant predictors of regrowth were immediate postoperative tumor volume ≥ 0.7 cm³ (HR 10.5, p = 0.020) and residual tumor location other than the internal auditory canal (IAC) (HR 6.2, p = 0.026). The mean time to regrowth was 33 months (range 5–127 months). The 2-, 5-, and 10-year regrowth-free survival rates were 90.6%, 86.8%, and 83%, respectively. In conclusion, significant residual tumor regression could occur within 2 years for a VS with an immediate postoperative tumor volume less than 0.7 cm³ or residual tumor in IAC.

Contrast MRI Findings for Spinal Schwannoma as Predictors of Tumor Proliferation and Motor Status

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

The goal of this study was to examine the relationship of the proliferation potency based on the MIB-1 index and motor status with features of T2-weighted images (T2WI) and contrast T1-weighted images (T1WI) of spinal schwannoma.

SUMMARY OF BACKGROUND DATA

Spinal schwannomas account for 55% of spinal tumors, but the relationship of cellular proliferation with MRI findings for spinal schwannoma is unknown.

METHODS

The subjects were 48 patients (22 males and 26 females) with spinal schwannoma who were classified into three subgroups: iso/homo, high/rim, and hetero/hetero, based on T2WI/contrast T1WI. A retrospective analysis of tumor size and MIB-1 index was performed in the context of these MRI findings. Intraoperative findings and pre- and postoperative motor performance were also examined.

RESULTS

The average tumor size was 32.4 mm (range 10-130 mm) and the average MIB-1 index was 3.8% (range 1-12). In the three subgroups, there were no significant differences in sex, age, duration of disease, tumor lesion, and dumbbell type. In the hetero/hetero group, the tumor size was significantly greater and the MIB-1 index was significantly higher (both P < 0.05), than the other two groups. The tumor adherence rate was significantly higher for hetero tumors (P < 0.05) and preoperative paralysis was more common in cases with tumor adhesion. The rate of paralysis improvement at 1 month was significantly lower for hetero tumors, but all cases had improved at 6 months.

CONCLUSION

Contrast T1WI MRI was useful for prediction of the proliferative activity and growth of spinal schwannomas, which are associated with increased tumor size and adhesion. A heterogeneous pattern on contrast T1WI indicated an increase in size and adhesion of the tumor. This pattern reflected the preoperative motor status and postoperative motor recovery.

LEVEL OF EVIDENCE

4.

Role of cyclins D1 and D3 in vestibular schwannoma

BACKGROUND

Vestibular schwannomas in younger patients have been observed to be larger in size and grow more quickly.

OBJECTIVE

This study aimed to evaluate the expression of three important cell cycle proteins, cyclin D1, cyclin D3 and Ki-67, in vestibular schwannoma patients separated into two age groups: ≤ 40 years or > 40 years.

METHOD

Immunohistochemical detection of cyclin D1, cyclin D3 and Ki-67 was undertaken in 180 surgically resected vestibular schwannomas.

RESULTS

The proliferation index of vestibular schwannomas was statistically higher in the ≤ 40 years age group compared to that in the > 40 years age group (mean of 4.52 vs 3.27, respectively; p = 0.01). Overexpression of cyclin D1 and cyclin D3 was found in 68 per cent and 44 per cent of tumours, respectively.

CONCLUSION

There was an increased Ki-67 proliferation index in the younger age group that appears to correlate with clinical behaviour. Vestibular schwannomas in both age groups show increased expression of cyclin D1 and cyclin D3.

The behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas

OBJECT

The authors evaluated the behavior of residual tumors and facial nerve outcomes after incomplete excision of vestibular schwannomas (VSs).

METHODS

The case records of all patients who underwent surgical treatment of VSs were analyzed. All patients in whom an incomplete excision had been performed were analyzed. Incomplete excision was defined as near-total resection (NTR), subtotal resection (STR), and partial resection (PR). Tumors in the NTR and STR categories were followed up with a wait-and-rescan approach, whereas the tumors in the PR category were subjected to a second-stage surgery and were excluded from this series. All patients included in the study underwent baseline MRI at the 3rd and 12th postoperative months, and repeat imaging was subsequently performed every year for 7-10 years postoperatively or as indicated clinically. Preoperative and postoperative facial function was noted.

RESULTS

Of the 2368 patients who underwent surgery for VS, 111 patients who had incomplete excisions of VSs were included in the study. Of these patients, 73 (65.77%) had undergone NTR and 38 (34.23%) had undergone STR. Of the VSs, 62 (55.86%) were cystic and 44 (70.97%) of these cystic VSs underwent NTR. The residual tumor was left behind on the facial nerve alone in 62 patients (55.86%), on the facial nerve and vessels in 2 patients (1.80%), on the facial nerve and brainstem in 15 patients (13.51%), and on the brainstem alone in 25 patients (22.52%). In the 105 patients with normal preoperative facial nerve function, postoperative facial nerve function was House-Brackmann (HB) Grades I and II in 51 patients (48.57%), HB Grade III in 34 patients (32.38%), and HB Grades IV-VI in 20 patients (19.05%). Seven patients (6.3%) showed evidence of tumor regrowth on follow-up MRI. All 7 patients (100%) who showed evidence of tumor regrowth had undergone STR. No patient in the NTR group exhibited regrowth. The Kaplan-Meier plot demonstrated a 5-year tumor regrowth-free survival of 92%, with a mean disease-free interval of 140 months (95% CI 127-151 months). The follow-up period ranged from 12 to 156 months (mean 45.4 months).

CONCLUSIONS

The authors' report and review of the literature show that there is undoubtedly merit for NTR and STR for preservation of the facial nerve. On the basis of this they propose an algorithm for the management of incomplete VS excisions. Patients who undergo incomplete excisions must be subjected to follow-up MRI for a period of at least 7-10 years. When compared with STR, NTR via an enlarged translabyrinthine approach has shown to have a lower rate of regrowth of residual tumor, while having almost the same result in terms of facial nerve function.

Clinicopathological factors related to regrowth of vestibular schwannoma after incomplete resection

Object

The authors retrospectively analyzed various clinicopathological factors to determine which are related to regrowth during a long-term follow-up period in patients who underwent incomplete vestibular schwannoma (VS) resection.

Methods

This study involved 74 patients (25 men and 49 women) in whom a VS was treated surgically via the lateral suboccipital approach, and who had postoperative follow-up periods exceeding 5 years. The mean follow-up was 104.1 months (range 60–241 months), and the mean patient age at surgery was 48.1 years (range 19–75 years). The tumors ranged in size from 0 mm (localized within the internal auditory canal) to 56 mm (28.3 ± 12.2 mm [mean ± SD]).

Results

Gross-total resection (GTR) was performed in 41 (55%) of the 74 patients; subtotal resection ([STR]; 90–99%) in 25 (34%); and partial resection ([PR]; < 90%) in 8 (11%). Regrowth rates in the GTR, STR, and PR groups were 2.4% (1 of 41 cases), 52% (13 of 25), and 62.5% (5 of 8), respectively, and the times to regrowth ranged from 6 to 76 months (median 31.9 months). The regrowth-free survival curves differed significantly between the complete (GTR) and incomplete (STR and PR) resection groups. Eighteen (54.5%) of the 33 patients who underwent incomplete resection showed evidence of regrowth during follow-up. Univariate and multivariate analyses of various factors revealed that both the thickness of the residual tumor, based on MR imaging after surgery, and the MIB-1 index were positively related to residual tumor regrowth. The receiver operating characteristic curves, plotted for both the thickness of the residual tumor and the MIB-1 index, identified the optimal cutoff points for these values as 7.4 mm (sensitivity 83.3%, specificity 86.7%) and 1.6 (sensitivity 83.3%, specificity 66.7%), respectively.

Conclusions

Greater residual tumor thickness, based on MR imaging after the initial surgery, and a higher MIB-1 index are both important factors related to postoperative tumor regrowth in patients who have undergone incomplete VS resection. These patients require frequent neuroimaging investigation during follow-up to assure early detection of tumor regrowth.

Labeling index in pituitary adenomas evaluated by means of MIB-1: is there a prognostic role? A critical review

OBJECTIVE

The present article presents an overview of the literature, and analyses the methods and the primary questions related to assessment of proliferation index using the Ki-67/MIB-1 labeling index in pituitary adenomas. Although atypical adenomas are characterized by their atypical morphological features by an elevated mitotic index, a Ki-67 (MIB-1) labeling index greater than 3% and extensive nuclear staining for p53, use of the proliferation index (LI) of pituitary adenomas in assessing the degree of tumor aggressiveness is a controversial topic in the literature, and there are disparate results involving many studies.

METHODS

A review of literature was carried out to correlate the role of Ki-67 LI and its correlation with clinical findings, tumor size, invasiveness, recurrence, adenoma subtype, adenoma doubling time, and pituitary carcinomas is addressed.

RESULTS

The prognosis cannot be predicted on the basis of the Ki-67 LI alone. Although there is no direct relation between Ki-67 LI and some of these variables and controversial data were found regarding some topics, our review justify the use of Ki-67 in the analysis of pituitary adenomas as an additional information for clinical decision.

CONCLUSION

Although assessment of proliferative may be helpful in predicting subsequent tumor recurrence or invasiveness, there are many other important and as yet unidentified factors pituitary tumors. It is clear that further research is needed to clarify these molecular mechanisms to predict those with a potentially poor clinical outcome.

BDNF mRNA expression is significantly upregulated in vestibular schwannomas and correlates with proliferative activity

The expression of neurotrophic factors, such as artemin, glial cell line-derived neurotrophic factor (GDNF), neurturin, transforming growth factors (TGF)-beta1/beta2 and brain-derived neurotrophic factor (BDNF), is enhanced in vestibular schwannomas compared to peripheral nerves. Furthermore, this upregulation may correlate with mitotic activity. Vestibular schwannoma arising from Schwann cells of the vestibular nerve are mostly benign and slow-growing. Most of the pathogenic mechanisms regulating the vestibular schwannoma growth process are unknown. An impaired growth regulation and imbalance between mitosis and apoptosis can be assumed. However, molecular mechanisms interfering with regulation of the vestibular schwannoma growth also modulated by mitogenic factors have to be identified. Neurotrophic factors are involved in regulation of developmental processes in neuronal tissues and regeneration after peripheral nerve trauma and also reveal mitogenic effects on glial cell populations. Gene expression profiles of artemin, BDNF, GDNF, TGF-beta1/beta2 and Ret were determined in the vestibular schwannoma in comparison to the peripheral nerve tissues by using semiquantitative RT-PCR. The expression data were correlated to the proliferation-associated Ki-67 labelling index. A significant higher BDNF expression was observed in the vestibular schwannoma, whereas gene expression of artemin and GDNF was upregulated in peripheral nerves. The correlation between LI and BDNF, TGF-beta1 and Ret was found to be significant in the vestibular schwannoma. Our results demonstrate a coherence between BDNF expression and proliferative activity in the vestibular schwannoma. Based on these results, we propose a pivotal role for BDNF in modulating the vestibular schwannoma growth.

[Size and proliferative index correlation in acoustic neuromas]

Acoustic neuromas are the most common tumors in the cerebellopontine angle. The molecular mechanisms involved in generation and growth of these tumors are not completely elucidated. Many radiological, clinic and immunohistochemistry data were correlated to tumor growth. We studied 11 acoustic neuromas surgically treated at Hospital São Paulo/Unifesp and correlated clinical and radiological data with proliferative index (Ki-67). The size of the tumors were positively correlationated with proliferative index. No other correlation had statistic significativity.

Aggressive vestibular schwannomas showing postoperative rapid growth - their association with decreased p27 expression

Vestibular schwannomas (VSs) are relatively slow growing tumors. However, some rapidly regrow or recur after surgical resection. The objective of this study was to identify those molecular characteristics predicting rapid recurrence after surgical resection. Immunohistochemically determined expressions of several cell cycle regulators and apoptosis-associated proteins in 12 cases of aggressive VS (AVS) and in 15 control cases of usual VS (UVS) cases were compared. The expressions of p53 and Bax (pro-apoptotic protein), Bcl-2 (anti-apoptotic protein), Fas, and Fas-L (apoptotic death receptor and ligand), caspase 3 (apoptotic effector caspase proteins), and p27 and p21 (cyclin-dependent kinase inhibitors) were analyzed using tissue array blocks. Loss of p27 expression was observed in 8 of 12 AVS cases (67%) and in 3 UVS cases (20%); p21 was expressed in all cases. Loss of Bax was observed in 3 AVS and 3 UVS cases. The anti-apoptotic protein, Bcl-2, was expressed in 9 AVS (75%) and 11 UVS (73%), and p53, Fas-L, and caspase 3 were negative and Fas was positive in all AVS and UVS cases. Of these, only the loss of p27 was statistically significant (P = 0.02). The loss of p27 in AVS may explain the unusually high proliferative potential of AVS versus UVS, and p27 may be a predictor of VS aggressiveness. The expressions of other apoptosis associated proteins were not significantly different in the two groups. This may be the first report to identify a molecular entity associated with aggressive VS. However, further studies are required.

Co-expression of Transforming Growth Factor-β1 and Glial Cell Line–Derived Neurotrophic Factor in Vestibular Schwannoma

HYPOTHESIS

Transforming growth factor-beta1, glial cell line-derived neurotrophic factor, and their receptors are expressed in vestibular schwannoma, and the expression data correlate with the proliferation activity (Ki-67 labeling index) and the clinical growth rate of vestibular schwannoma tissue.

BACKGROUND

Glial cell line-derived neurotrophic factor is a potent growth factor for the central and peripheral nervous system. Recent results demonstrate that glial cell line-derived neurotrophic factor requires transforming growth factor-beta to exert its trophic effect on neural tissue. A functional role, including that in Schwann cell proliferation, is discussed for both transforming growth factor-beta1 and glial cell line-derived neurotrophic factor.

METHODS

Immunohistochemical analysis for transforming growth factor-beta1 and glial cell line-derived neurotrophic factor and their receptors TbetaR II, GFRalpha-1, and Ret was performed on formalin-fixed, paraffin-embedded archival surgical specimens. The Ki-67 labeling index (mean Ki-67 labeling index and highest Ki-67 labeling index for Antoni Type A and Type B regions) and the clinical growth rate of vestibular schwannoma were determined and correlated with the expression patterns of the examined neurotrophic factors and their receptors.

RESULTS

Results demonstrate co-expression of transforming growth factor-beta1 and glial cell line-derived neurotrophic factor with higher levels in Antoni Type A than in Antoni Type B regions. Ninety-five percent of vestibular schwannomas exhibited transforming growth factor-beta1 immunoreactivity, and glial cell line-derived neurotrophic factor expression was found in 100% of vestibular schwannoma specimens. Fifty percent of vestibular schwannoma displayed TbetaR II immunostaining, 100% showed positive reactions for GFRalpha-1, and 86% showed positive reactions for Ret. Statistical analysis revealed no significant correlation in neurotrophin expression related to sex, age, tumor size, clinical growth rate, or Ki-67-labeling indices.

CONCLUSIONS

Expression of transforming growth factor-beta1 and glial cell line-derived neurotrophic factor may suggest a biological role for both growth factors in vestibular schwannomas. Trophic transforming growth factor-beta/glial cell line-derived neurotrophic factor synergism seems possible and is underscored by co-expression of both neurotrophic factors and their receptors.

Medulloblastoma: evaluation of proliferative index by monoclonal antibody Mib-1, its prognostic correlation and therapeutic implications

In the past few years, the monoclonal antibody MIB-1 has been used by researchers in order to retrospectively study paraffin imbibed tumor fragments. The medulloblastoma is the most common malignant central nervous system tumor in childhood. The objectives were: determination of the mean Mib-1 LI value from these patients, as well as the prognostic value of the method.This retrospective study represents an analysis of the cellular proliferation index of posterior fossa medulloblastomas collected from 22 patients at A.C. Camargo Hospital, from January 1990 to December 1999. The histopathological diagnosis was confirmed by H&E and proliferative index (LI) was achived with Mib-1 which detects proliferating cells during G1, G2, S and M phases.The results demostrated that the mean Mib-1 was 30,1%, and ranged from 5,2% to 62,0%.In conclusion, this method has prognostic value, has to be used as routine for patients harboring medulloblastomas and the ones who have PI greater than the mean value found in this study, should be treated aggressively.

Determinants of tumor size and growth in vestibular schwannomas

OBJECT

This study was undertaken to analyze factors associated with the size of unilateral vestibular schwannomas (VSs).

METHODS

A retrospective analysis of an unselected and sequential series of 433 patients with unilateral VSs was conducted. Tumor size was defined by the largest dimension of the tumor in the cerebellopontine angle, and the size was tested for a relationship with patient age and sex. In a subgroup of 231 patients in whom data were available, tumor size was also tested for a relationship with tumor cysts or the absence of an internal auditory canal (IAC) component. Some patients underwent a period of surveillance with serial imaging studies to monitor for tumor growth. Data from these patients, excluding those with cystic tumors, were analyzed to see if tumor growth was related to patient age, sex, or tumor size. CONCLUSIONS; Larger tumors were found in younger patients, in females, in the subgroup of cystic tumors, and in patients in whom there was no tumor component in the IAC. The probable explanations for these larger tumors are a faster growth rate and/or a delay in symptom onset. When untreated tumors are managed with observation, measurable growth is more often seen in larger tumors, although smaller tumors have a faster relative growth rate than larger ones.

The comparison between the growth fraction of bilateral vestibular schwannomas in neurofibromatosis 2 (NF2) and unilateral vestibular schwannomas using the monoclonal antibody MIB 1

Formalin-fixed paraffin sections of 55 consecutive bilateral vestibular schwannomas in 46 patients with neurofibromatosis 2 (NF2), and 50 patients with unilateral vestibular schwannomas were investigated immunohistochemically with the monoclonal antibody MIB 1 directed against recombinant parts of Ki-67 antigen. The immunohistochemical staining was carried out on dewaxed microwave oven-processed paraffin sections of formalin-fixed tumour tissues. The labelling index (LI) obtained was compared to clinical and histological findings in both groups. There was no correlation between the LI and age of the patients, tumour size, or histological type of tumour (Antoni A or B). Vestibular schwannomas in NF2 showed higher LI than unilateral vestibular schwannomas: the maximal LI found per section (LI max) ranged from 0.4 to 17.6% (mean, 2.7%) in NF2 schwannomas, and from 0 to 9% (mean, 2.2%) in unilateral schwannomas. These differences may express immunohistochemically some clinical and morphological differences between bilateral and unilateral vestibular schwannomas.