Diagnostic value and safety of stereotactic biopsy for pediatric brainstem tumors: own experience, a systematic review and meta-analysis of 693 cases

OBJECTIVE Recent studies have shed light on the molecular makeup of diffuse intrinsic pontine gliomas and led to the identification of potential treatment targets for these lesions, which account for the majority of pediatric brainstem tumors (pedBSTs). Therefore, stereotactic biopsy driven molecular characterization of pedBSTs may become an important prerequisite for the management of these fatal brain tumors. The authors conducted a systemic review and meta-analysis to precisely determine the safety and diagnostic success of stereotactic biopsy of pedBSTs. METHODS A systematic search of PubMed, EMBASE, and the Web of Science yielded 944 potentially eligible abstracts. Meta-analysis was conducted on 18 studies (including the authors' own institutional series), describing a total of 735 biopsy procedures for pedBSTs. The primary outcome measures were diagnostic success and procedure-related complications. Pooled estimates were calculated based on the Freeman-Tukey double-arcsine transformation and DerSimonian-Laird random-effects model. Heterogeneity, sensitivity, and meta-regression analyses were also conducted. RESULTS The weighted average proportions across the analyzed studies were 96.1% (95% CI 93.5%-98.1%) for diagnostic success, 6.7% (95% CI 4.2%-9.6%) for overall morbidity, 0.6% (95% CI 0.2%-1.4%) for permanent morbidity, and 0.6% (95% CI 0.2%-1.3%) for mortality. Subgroup analyses at the study level identified no significant correlation between the outcome measures and the distribution of the chosen biopsy trajectories (transfrontal vs transcerebellar), age, year of publication, or the number of biopsy procedures annually performed in each center. CONCLUSION Stereotactic biopsy of pedBSTs is safe and allows successful tissue sampling as a prerequisite for the molecular characterization and the identification of potentially druggable targets toward more individualized treatment concepts to improve the outcome for children harboring such lesions

Long-term follow-up after stereotactic radiosurgery of intracanalicular acoustic neurinoma

Abstract Background The management of solely intracanalicular acoustic neurinoma (iAN) includes observation, microsurgical resection and radiation therapy. Treatment goals are long-term tumor control, hearing preservation and concurrently low side-effects. Stereotactic radiosurgery (SRS) has evolved as an alternative first-line treatment for small AN. Here we report about the long-term follow-up of a unique cohort of patients with iAN after LINAC or Cyberknife® based SRS. Methods In this single center retrospective analysis, we included all patients with iAN who underwent single session LINAC or Cyberknife® based SRS between 1993 and 2015, and who had a minimum follow-up period of six weeks. Patient data were analyzed in terms of radiological and clinical tumor control (no further treatment necessary), subjective preservation of serviceable hearing, objective change in pure tone averages (PTA), and adverse events rated by the Common Terminology Criteria for Adverse Events (CTCAE; v4.03). Results Forty-nine patients (f/m = 21/28, median age 54 ± 12, range 20–77 years) were identified. Mean tumor volumes were 0.24 ± 0.12 cm3 (range, 0.1–0.68 cm3), the mean marginal dose was 12.6 ± 0.6 Gy (range, 11.0–14.0 Gy) and the prescription isodose was 75 ± 7.4% (range, 47–86%). Mean follow-up time was 65 months (range, 4–239 months). Radiological tumor control was 100% during further follow-up. 17 (35%) out of 49 patients had lost serviceable hearing prior to SRS. Those with preserved serviceable hearing remained stable in 78% (n = 25/32) at the last follow-up (LFU). The median PTA (n = 16) increased from 25.6 dB prior to SRS to 43.8 dB at LFU. Mild adverse events were observed temporarily in two patients (4%): one with CTCAE grade 1 facial nerve disorder after 3 months, resolving three months later, and one with CTCAE grade 2 facial muscle weakness resolving after 12 months. Three patients described permanent mild symptoms CTCAE grade 1 without limiting daily life (facial weakness n = 1, vertigo n = 2). Conclusion SRS for iAN shows long-term reliable tumor control with a high rate of hearing preservation without considerable permanent side effects, and can be proposed as a safe and effective treatment alternative to microsurgical resection