Molecular Diagnostics as a Tool to Personalize Treatment in Adult Glioma Patients

Stereotactic frame-based biopsy of infratentorial lesions via the suboccipital-transcerebellar approach with the Zamorano-Duchovny stereotactic system-a retrospective analysis of 79 consecutive cases

OBJECTIVE

Lesions of the posterior fossa (brainstem and cerebellum) are challenging in diagnosis and treatment due to the fact that they are often located eloquently and total resection is rarely possible. Therefore, frame-based stereotactic biopsies are commonly used to asservate tissue for neuropathological diagnosis and further treatment determination. The aim of our study was to assess the safety and diagnostic success rate of frame-based stereotactic biopsies for lesions in the posterior fossa via the suboccipital-transcerebellar approach.

METHODS

We performed a retrospective database analysis of all frame-based stereotactic biopsy cases at our institution since 2007. The aim was to identify all surgical cases for infratentorial lesion biopsies via the suboccipital-transcerebellar approach. We collected clinical data regarding outcomes, complications, diagnostic success, radiological appearances, and stereotactic trajectories.

RESULTS

A total of n = 79 cases of stereotactic biopsies for posterior fossa lesions via the suboccipital-transcerebellar approach (41 female and 38 male) utilizing the Zamorano-Duchovny stereotactic system were identified. The mean age at the time of surgery was 42.5 years (± 23.3; range, 1-87 years). All patients were operated with intraoperative stereotactic imaging (n = 62 MRI, n = 17 CT). The absolute diagnostic success rate was 87.3%. The most common diagnoses were glioma, lymphoma, and inflammatory disease. The overall complication rate was 8.7% (seven cases). All patients with complications showed new neurological deficits; of those, three were permanent. Hemorrhage was detected in five of the cases having complications. The 30-day mortality rate was 7.6%, and 1-year survival rate was 70%.

CONCLUSIONS

Our data suggests that frame-based stereotactic biopsies with the Zamorano-Duchovny stereotactic system via the suboccipital-transcerebellar approach are safe and reliable for infratentorial lesions bearing a high diagnostic yield and an acceptable complication rate. Further research should focus on the planning of safe trajectories and a careful case selection with the goal of minimizing complications and maximizing diagnostic success.

[Primary tumors of the brain stem. State of the problem]

Primary brainstem gliomas are still poorly studied in neurooncology. This concept includes tumors with different histological and genetic features, as well as variable clinical course and outcomes. Nevertheless, treatment implies radiotherapy without a clear idea of morphological substrate of disease in 80% of cases. Small number of studies and insufficient data on histological and genetic nature of brainstem tumors complicate clear diagnostic and treatment algorithms. This review provides current information regarding primary glial brainstem tumors. Appropriate problems and objectives are highlighted. The purpose of the review is to provide a comprehensive and updated understanding of the current state of brainstem glial tumors and to identify areas requiring further study for improvement of diagnosis and treatment of these diseases. Brainstem tumors are an understudied problem with small amount of data that complicates optimal treatment strategies. Further researches and histological verification are required to develop new methods of therapy, especially for diffuse forms of neoplasms.

Safety and efficacy of brainstem biopsy in children and young adults

OBJECTIVE

Biopsies of brainstem lesions are performed to establish a diagnosis in the setting of an atypical clinical or radiological presentation, or to facilitate molecular studies. A better understanding of the safety and diagnostic yield of brainstem biopsies would help guide appropriate patient selection.

METHODS

All patients who underwent biopsy of a brainstem lesion during the period from January 2011 to June 2019 were reviewed. Demographic, radiological, surgical, and outcome data were collected.

RESULTS

A total of 58 patients underwent 65 brainstem biopsies during the study period. Overall, the median age was 7.6 years (IQR 3.9-14.2 years). Twenty-two of the 65 biopsies (34%) were open, 42 (65%) were stereotactic, and 1 was endoscopic. In 3 cases (5%), a ventriculoperitoneal shunt was placed, and in 9 cases (14%), a posterior fossa decompression was performed during the same operative session as the biopsy. An intraoperative MRI (iMRI) was performed in 28 cases (43%). In 3 of these cases (11%), the biopsy was off target and additional samples were obtained during the same procedure. New neurological deficits were noted in 5 cases (8%), including sensory deficits, ophthalmoparesis/nystagmus, facial weakness, and hearing loss; these deficits persisted in 2 cases and were transient in 3 cases. A pseudomeningocele occurred in 1 patient; no patients developed a CSF leak or infection. In 8 cases (13%) an additional procedure was needed to obtain a diagnosis.

CONCLUSIONS

Brainstem biopsies are safe and effective. Target selection and approach should be a collaborative effort. iMRI can be used to assess biopsy accuracy in real time, thereby allowing any adjustment if necessary.

Towards the lean lab: the industry challenge

In anatomic pathology, the current state encompassing the pre-analytic processes of tissue collection, handling, examination, preparation, processing, and storage are largely uncontrolled, inconsistently performed, and/or not standardized according to the sound scientific data. Pre-analytic defects result in nearly three-quarters of the problems in laboratory diagnostics. This is evident in quality surveys from well-respected institutions that document high miss rates in the required basics of information related to patient and tissue identity, let alone parameters documenting quality aspects related to the surgical specimen and its preservation. This talk will describe the historical approach to tissue processing and identify gaps from worldwide observations in current laboratory practices. It will also offer potential methodological and technological solutions and process improvements that laboratories may consider in serving the ultimate users of pathology information: the clinician and the patient. It illustrates the need for scientifically validated specimen guidelines and a performance based, standardized and documented "chain of custody" of the pre-analytical steps from the patient's body through fixation. For thought leaders and professional standard setters, opportunities for optimizing molecular studies exist in specimen collection, transfer, grossing, fixation, and decalcification protocols. In this evolving era of molecular profiling and personalized therapeutic decision-making, a well-reasoned and coordinated focus on pre-analytic processes that optimizes specimens for subsequent testing will result in: Improved specimen quality for molecular testing Improved accuracy of diagnostic and molecular test results Reduced Turnaroundtimes for same-day diagnosis Enhanced satisfaction of clinicians and patients.

Correlation between magnetic resonance imaging findings and histological diagnosis of intrinsic brainstem lesions in adults

Management of brainstem mass lesions remains a controversial issue, especially when the lesion cannot be excised and when infiltration occurs; moreover, the benefits of a stereotactic procedure are still under debate. In most studies, treatment decisions are based solely on MRI features and do not include a histopathological diagnosis. In the current study, we compared MRI characteristics with histopathological findings of intrinsic brainstem lesions and identified the characteristics associated with the diagnosis of pathologies other than diffuse glioma. From February 1988 through August 2007, 96 brainstem biopsies were performed at the Roger Salengro Hospital in Lille, France, on adult patients with intrinsic brainstem lesions not amenable to excision. Of the 96 patients, 42 were women and 54 were men, with a mean age of 41 years (range, 18-75 years). Data analysis of the MRI findings revealed focal (P < .05) and contrast enhancing lesions (P < .05), and these lesions were significant factors associated with the diagnosis of pathologies other than diffuse glioma. Focal lesions were a significant factor associated with a diagnosis of nontumor lesions (P < .05). In conclusion, the diagnostic effect of stereotactic biopsy on intrinsic brainstem lesions was greater in patients with focal or enhancing lesions shown by MRI, in whom the diagnosis of diffuse glioma was less frequent.

Correlation among magnetic resonance imaging findings, prognostic factors for survival, and histological diagnosis of intrinsic brainstem lesions in children

OBJECT

The aim of this study was to compare MR imaging characteristics with histopathological findings of intrinsic brainstem lesions and also to show the prognostic factors in patients with diffuse brainstem glioma.

METHODS

Between February 1988 and August 2007, 44 brainstem biopsies were performed at the Roger Salengro Hospital in Lille, France, in children with intrinsic brainstem lesions not amenable to excision. Twenty-six were female and 18 male, and the mean age was 6 years.

RESULTS

Histological evaluation revealed diffuse brainstem glioma in all patients with diffuse nonenhancing brainstem lesions. Diffuse brainstem glioma was found in 18 patients (90%) with diffuse enhancing brainstem lesions. Pathological entities different from diffuse glioma were verified in 2 patients (10%)-1 with ependymoma and 1 with ganglioglioma. In 4 of 5 patients with a focal nonenhancing brainstem lesion, the histopathological diagnosis was diffuse low-grade glioma. In 6 of 10 patients with focal enhancing brainstem lesion, the diagnosis was diffuse brainstem glioma, and pathological entities different from diffuse brainstem glioma were verified in 2 (20%), both with pilocytic astrocytoma. The mean 1-year actuarial survival rates for patients classified with low-grade and high-grade glioma were 80.4% ± 0.08% and 48.6% ± 0.14%, respectively.

CONCLUSIONS

The impact of stereotactic biopsy on intrinsic brainstem lesions was greater in patients with MR imaging-documented enhancing lesions in whom the diagnosis of diffuse glioma was less frequent. Patients with low-grade glioma seem to have longer survival than those with high-grade glioma.

Molecular tools: biology, prognosis, and therapeutic triage

Diffuse gliomas in adults continue to have a dismal prognosis with the current standard therapeutic methods, including maximal surgical resection, radiation, and chemotherapy. The pathogenesis of adult glioma is complex, involving the loss of function of tumor suppressor genes and activation of oncogenes, which are involved in a network of interconnected signaling pathways. Through activation of these pathways, characteristics of malignant gliomas, including uncontrolled proliferation and growth, invasion, and angiogenesis, are driven. Evolving therapeutic approaches are focused on specifically targeting these genetic lesions. This content gives an overview of the current knowledge about the pathogenesis of adult diffuse gliomas, emphasizing new targeted treatment approaches.

The nature and timing of specific copy number changes in the course of molecular progression in diffuse gliomas: further elucidation of their genetic "life story"

Up till now, typing and grading of diffuse gliomas is based on histopathological features. However, more objective tools are needed to improve reliable assessment of their biological behavior. We evaluated 331 diffuse gliomas for copy number changes involving 1p, 19q, CDKN2A, PTEN and EGFR(vIII) by Multiplex Ligation-dependent Probe Amplification (MLPA®, Amsterdam, The Netherlands). Specifically based on the co-occurrence of these aberrations we built a model for the timing of the different events and their exact nature (hemi- → homozygous loss; low-level gain → (high-copy) amplification) in the course of molecular progression. The mutation status of IDH1 and TP53 was also evaluated and shown to correlate with the level of molecular progression. The relevance of the proposed model was confirmed by analysis of 36 sets of gliomas and their 39 recurrence(s) whereas survival analysis for anaplastic gliomas confirmed the actual prognostic relevance of detecting molecular malignancy. Moreover, based on our results, molecular diagnostic analysis of 1p/19q can be further improved as different aberrations were identified, some of them being indicative for advanced molecular malignancy rather than for favorable tumor behavior. In conclusion, identification of molecular malignancy as proposed will aid in establishing a risk profile for individual patients and thereby in therapeutic decision making.

Stereotactic biopsy of diffuse pontine lesions in children

OBJECT

Empirical radiotherapy is the current treatment for children with diffuse pontine lesions that have imaging characteristics of an infiltrative malignant astrocytoma. The use of chemotherapeutic agents is, however, currently under investigation in the treatment of these tumors. To be included into a trial, patients need a definitive histological diagnosis. The authors present their prospective study of the stereotactic biopsy of these lesions during a 4-year period.

METHODS

A suboccipital, transcerebellar approach was used to obtain biopsy samples in 24 children.

RESULTS

Two patients suffered deficits. Both had a transient (< 2 months) new cranial nerve palsy; one of these patients also experienced an exacerbation of a preoperative hemiparesis. No patient died during the perioperative period. A histological diagnosis was made in all 24 patients as follows: 22 had a malignant infiltrative astrocytoma, one had a low-grade astrocytoma, and one had a pilocytic astrocytoma. The diagnosis of the latter two patients affected the initial treatment after the biopsy.

CONCLUSIONS

The findings of this study imply that stereotactic biopsy sampling of a diffuse pontine tumor is a safe procedure, is associated with minimal morbidity, and has a high diagnostic yield. A nonmalignant tumor was identified in two of the 24 patients in whom the imaging findings were characteristic of a malignant infiltrative astrocytoma. With the advent of new treatment protocols, stereotactic biopsy sampling, which would allow specific tumor characterization of diffuse pontine lesions, may become standard.