scholarly journals RADT-19. EFFECTS OF RADIATION DOSE-RATE AND TUMOR CHARACTERISTICS ON LOCAL CONTROL AND TOXICITY AFTER RADIOSURGERY FOR ACOUSTIC NEUROMAS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii185-ii185
Author(s):  
Conrad Josef Villafuerte ◽  
Fred Gentili ◽  
David Shultz ◽  
Alejandro Berlin ◽  
Robert Heaton ◽  
...  
Keyword(s):  
Dose Rate ◽  
Proportional Hazards Model ◽  
Multivariable Analysis ◽  
Tumor Resection ◽  
Local Failure ◽  
Tumor Control ◽  
Tumor Diameter ◽  
Radiation Dose Rate ◽  
Acoustic Neuromas

Abstract INTRODUCTION The effect of stereotactic radiosurgery (SRS) dose-rate on tumor control for acoustic neuroma (AN, or vestibular schwannoma) is unclear. METHODS This was a retrospective study of all patients treated for AN with frame-based cobalt-60 SRS at the Toronto Western Hospital between 2005-2019. Dose rates on the day of SRS were calculated from the calibration dose-rate while accounting for the cobalt-60 half-life of 5.2713 years. Local failure was defined as continued tumor growth >36 months post-SRS, tumor resection for LF, or use of any repeat SRS for LF. Cumulative incidence of LF was reported after accounting for competing risks of death, on a per-lesion basis. Comparisons of actuarial LF were made using Gray’s test. Multivariable analysis of LF was performed using a proportional hazards model. RESULTS A total of 607 patients were treated for 617 acoustic neuromas. Median follow-up was 5.0 years. 158 tumors (26%) were cystic. 71 tumors (12%) had previous resection. Nine patients received 10-11 Gy due to large tumor size; all remaining patients received 12 Gy to approximately the 50% isodose line. Median dose rate was 2.4 Gy/min (range, 1.3-3.7). There was no association between dose rate and LF (≥ 2.4 Gy/min vs. < 2.4 Gy/min, 6.07% vs. 6.12% at 5-year follow-up, p = 0.75). The adjusted local failure-specific hazard ratio (HR) for dose rate (per Gy/min) was 1.2 (95% CI 0.69-2.1, p = 0.52). Patients with previous surgery had higher LF, with a HR of 3.6 (95% CI 1.7-7.8, p = 0.0012), after adjusting for presence of cysts (HR 0.27, p = 0.034) and maximum tumor diameter (HR 1.055 per cm, p = 0.071). CONCLUSIONS In a large cohort of patients with acoustic neuromas, radiosurgery dose-rate was not associated with tumor control. Previous resection was a strong risk factor for local failure after SRS.

Staged Stereotactic Irradiation for Acoustic Neuroma

Neurosurgery ◽  
2005 ◽  
Vol 56 (6) ◽  
pp. 1254-1263 ◽  
Author(s):  
Steven D. Chang ◽  
Iris C. Gibbs ◽  
Gordon T. Sakamoto ◽  
Elizabeth Lee ◽  
Adetokunbo Oyelese ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Acoustic Neuroma ◽  
Clinical Investigation ◽  
Cranial Nerves ◽  
Hearing Preservation ◽  
Tumor Control ◽  
Tumor Diameter ◽  
Acoustic Neuromas ◽  
Class 1

Abstract OBJECTIVE: Stereotactic radiosurgery has proven effective in the treatment of acoustic neuromas. Prior reports using single-stage radiosurgery consistently have shown excellent tumor control, but only up to a 50 to 73% likelihood of maintaining hearing at pretreatment levels. Staged, frame-based radiosurgery using 12-hour interfraction intervals previously has been shown by our group to achieve excellent tumor control while increasing the rate of hearing preservation at 2 years to 77%. The arrival of CyberKnife (Accuray, Inc., Sunnyvale, CA) image-guided radiosurgery now makes it more practical to treat acoustic neuroma with a staged approach. We hypothesize that such factors may further minimize injury of adjacent cranial nerves. In this retrospective study, we report our experience with staged radiosurgery for managing acoustic neuromas. METHODS: Since 1999, the CyberKnife has been used to treat more than 270 patients with acoustic neuroma at Stanford University. Sixty-one of these patients have now been followed up for a minimum of 36 months and form the basis for the present clinical investigation. Among the treated patients, the mean transverse tumor diameter was 18.5 mm, whereas the total marginal dose was either 18 or 21 Gy using three 6- or 7-Gy fractions. Audiograms and magnetic resonance imaging were obtained at 6-months intervals after treatment for the first 2 years and then annually thereafter. RESULTS: Of the 61 patients with a minimum of 36 months of follow-up (mean, 48 mo), 74% of patients with serviceable hearing (Gardner-Robinson Class 1–2) maintained serviceable hearing at the last follow-up, and no patient with at least some hearing before treatment lost all hearing on the treated side. Only one treated tumor (2%) progressed after radiosurgery; 29 (48%) of 61 decreased in size and 31 (50%) of the 61 tumors were stable. In no patients did new trigeminal dysfunction develop, nor did any patient experience permanent injury to their facial nerve; two patients experienced transient facial twitching that resolved in 3 to 5 months. CONCLUSION: Although still preliminary, these results indicate that improved tumor dose homogeneity and a staged treatment regimen may improve hearing preservation in acoustic neuroma patients undergoing stereotactic radiosurgery.

Stereotactic radiotherapy for the treatment of acoustic neuromas

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 362-372 ◽  
Author(s):  
Michael T. Selch ◽  
Alessandro Pedroso ◽  
Steve P. Lee ◽  
Timothy D. Solberg ◽  
Nzhde Agazaryan ◽  
...  
Keyword(s):  
Stereotactic Radiotherapy ◽  
Tumor Size ◽  
Cranial Nerve ◽  
Target Volume ◽  
Tumor Control ◽  
Content Type ◽  
Seventh Cranial Nerve ◽  
Acoustic Neuromas ◽  
Fine Print

Object. The authors sought to assess the safety and efficacy of stereotactic radiotherapy when using a linear accelerator equipped with a micromultileaf collimator for the treatment of patients with acoustic neuromas. Methods. Fifty patients harboring acoustic neuromas were treated with stereotactic radiotherapy between September 1997 and June 2003. Two patients were lost to follow-up review. Patient age ranged from 20 to 76 years (median 59 years), and none had neurofibromatosis. Forty-two patients had useful hearing prior to stereotactic radiotherapy. The fifth and seventh cranial nerve functions were normal in 44 and 46 patients, respectively. Tumor volume ranged from 0.3 to 19.25 ml (median 2.51 ml). The largest tumor dimension varied from 0.6 to 4 cm (median 2.2 cm). Treatment planning in all patients included computerized tomography and magnetic resonance image fusion and beam shaping by using a micromultileaf collimator. The planning target volume included the contrast-enhancing tumor mass and a margin of normal tissue varying from 1 to 3 mm (median 2 mm). All tumors were treated with 6-MV photons and received 54 Gy prescribed at the 90% isodose line encompassing the planning target volume. A sustained increase greater than 2 mm in any tumor dimension was defined as local relapse. The follow-up duration varied from 6 to 74 months (median 36 months). The local tumor control rate in the 48 patients available for follow up was 100%. Central tumor hypodensity occurred in 32 patients (67%) at a median of 6 months following stereotactic radiotherapy. In 12 patients (25%), tumor size increased 1 to 2 mm at a median of 6 months following stereotactic radiotherapy. Increased tumor size in six of these patients was transient. In 13 patients (27%), tumor size decreased 1 to 14 mm at a median of 6 months after treatment. Useful hearing was preserved in 39 patients (93%). New facial numbness occurred in one patient (2.2%) with normal fifth cranial nerve function prior to stereotactic radiotherapy. New facial palsy occurred in one patient (2.1%) with normal seventh cranial nerve function prior to treatment. No patient's pretreatment dysfunction of the fifth or seventh cranial nerve worsened after stereotactic radiotherapy. Tinnitus improved in six patients and worsened in two. Conclusions. Stereotactic radiotherapy using field shaping for the treatment of acoustic neuromas achieves high rates of tumor control and preservation of useful hearing. The technique produces low rates of damage to the fifth and seventh cranial nerves. Long-term follow-up studies are necessary to confirm these findings.

RADT-30. MULTISESSION RADIOSURGERY ALONE FOR TREATMENT OF PRESUMED MENINGIOMAS: AN INTERIM REPORT FROM A SINGLE INSTITUTION PROTOCOL

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi47-vi48
Author(s):  
Michael Carrasquilla ◽  
Alexander Tai ◽  
Matthew Forsthoefel ◽  
Edina Wang ◽  
Siyuan Lei ◽  
...  
Keyword(s):  
Local Control ◽  
Tumor Resection ◽  
Symptom Improvement ◽  
Tumor Control ◽  
Single Institution ◽  
Robotic Radiosurgery ◽  
Early Results ◽  
Alternative Treatment Option

Abstract PURPOSE Meningiomas are the most commonly diagnosed primary intracranial tumor. Resection and single-fraction radiosurgery are treatment options with well-established long-term outcomes data. Multisession radiosurgery is an alternative treatment option with promising early results. However, mature outcomes literature does not yet exist. In this study, we report our institution’s interim results on the efficacy and safety of 5-fraction radiosurgery alone for radiographically diagnosed meningiomas. MATERIALS AND METHODS Between 2005-2015 all patients who completed treatment on a single institution protocol utilizing 5-fraction robotic radiosurgery alone for the treatment of progressing radiographically diagnosed meningiomas were eligible for inclusion. Local control was calculated using the Kaplan-Meier Method. RESULTS Forty-four consecutive predominately female patients (84%) ranging in age from 33-85 (median: 59) were included in the present study. Median tumor volume was 4.05mm3 (range: 0.94-15.4mm3) and the majority of tumors were located at the base of skull (66%). A median dose of 25Gy (range: 25Gy-35Gy), was delivered to a median isodose line of 82%, (range: 70%-90%) over a median of 7 days (range: 5-11 days). Acute toxicity was minimal with 7 patients (15%) requiring a short course of steroids for symptomatic edema during treatment. Of 16 patients who presented with a cranial nerve deficit, symptom improvement was noted in 11 patients (69%). No permanent treatment related toxicity was noted in our cohort. The median radiographic follow-up was 6.9 years (range: 0.5-14.8 years). The 5 and 8-year local control rates were 100% and 95%. The median time to local failure (n=2) in our cohort was 8.2 years. CONCLUSIONS The treatment of radiographically diagnosed meningiomas with 5-fraction robotic radiosurgery provides excellent local control to date, with low rates of acute and late toxicity. However, with late failures noted in our series, continued follow-up is needed to determine the optimal dose required for long-term tumor control.

Long-term outcomes of Gamma Knife radiosurgery in patients with vestibular schwannomas

2011 ◽  
Vol 114 (2) ◽  
pp. 432-440 ◽  
Author(s):  
Erin S. Murphy ◽  
Gene H. Barnett ◽  
Michael A. Vogelbaum ◽  
Gennady Neyman ◽  
Glen H. J. Stevens ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
Vestibular Schwannomas ◽  
Tumor Control ◽  
Tumor Diameter ◽  
Long Term Effects ◽  
Median Dose ◽  
The Mean

Object The authors sought to determine the long-term tumor control and side effects of Gamma Knife radiosurgery (GKRS) in patients with vestibular schwannomas (VS). Methods One hundred seventeen patients with VS underwent GKRS between January 1997 and February 2003. At the time of analysis, at least 5 years had passed since GKRS in all patients. The mean patient age was 60.9 years. The mean maximal tumor diameter was 1.77 ± 0.71 cm. The mean tumor volume was 1.95 ± 2.42 ml. Eighty-two percent of lesions received 1300 cGy and 14% received 1200 cGy. The median dose homogeneity ratio was 1.97 and the median dose conformality ratio was 1.78. Follow-up included MR imaging or CT scanning approximately every 6–12 months. Rates of progression to surgery were calculated using the Kaplan-Meier method. Results Of the 117 patients in whom data were analyzed, 103 had follow-up MR or CT images and 14 patients were lost to follow-up. Fifty-three percent of patients had stable tumors and 37.9% had a radiographically documented response. Imaging-documented tumor progression was present in 8 patients (7.8%), but in 3 of these the lesion eventually stabilized. Only 5 patients required a neurosurgical intervention. The estimated 1-, 3-, and 5-year rates of progression to surgery were 1, 4.6, and 8.9%, respectively. One patient (1%) developed trigeminal neuropathy, 4 patients (5%) developed permanent facial neuropathy, 3 patients (4%) reported vertigo, and 7 patients (18%) had new gait imbalance following GKRS. Conclusions Gamma Knife radiosurgery results in excellent local control rates with minimal toxicity for patients with VS. The authors recommend standardized follow-up to gain a better understanding of the long-term effects of GKRS.

Impact of new systemic therapies on overall survival (OS) of patients (pts) with metastatic castration resistant prostate cancer (mCRPC) in a hospital-based registry.

2018 ◽  
Vol 36 (6_suppl) ◽  
pp. 203-203
Author(s):  
Edoardo Francini ◽  
Kathryn P. Gray ◽  
Grace Shaw ◽  
Carolyn Evan ◽  
Anis Hamid ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proportional Hazards Model ◽  
Multivariable Analysis ◽  
Cox Proportional Hazards Model ◽  
Castration Resistant Prostate Cancer ◽  
New Therapies ◽  
Risk Of Death ◽  
Radium 223 ◽  
Ecog Ps

203 Background: From 2004 to 2009, mCRPC treatment options were limited to docetaxel (D), mitoxantrone, first generation anti-androgens (AA), estrogens, steroids, and ketoconazole, with only D showing OS benefit. Since 2010, five new therapies prolonged OS and were approved for mCRPC: sipuleucel-T, cabazitaxel, abiraterone acetate, enzalutamide, and radium 223. We sought to assess the aggregate impact of new therapies on OS. Methods: We used the DFCI CRIS database to identify cohorts of pts who developed mCRPC between 2004-2007 (cohort A) and 2010-2013 (cohort B). Therapies for mCRPC in each cohort were annotated. Given the median follow-up (FU) was 10.6 years (yrs) in cohort A and 4.6 yrs in cohort B, we evaluated OS, defined as time from mCRPC per PCWG3 criteria to death from all causes or last follow-up visit within 5 yrs (truncated OS). Kaplan-Meier method estimated the time to events distribution with median (95% CI). Cox proportional hazards model evaluated effects of treatment groups on disease outcomes with estimates of hazard ratio (95% CI). Results: Of the 583 pts identified, 317 (54%) were in cohort A and 266 (46%) in cohort B. Pts in cohort B had a significantly longer median OS (p<0.001), a 5-yr OS of 26% vs. 10%, and a 31% reduced risk of death compared to cohort A (HR=0.69; 95% CI, 0.57-0.83) (see Table). On multivariable analysis, adjusting for prior local Rx, ECOG PS, and the number of agents received, longer OS is confirmed associated with cohort B vs. A and also with ECOG PS status 0 vs. 1, number of agents received 5-12 vs. ≤3. Conclusions: Using the DFCI prostate cancer database, therapies approved for mCRPC since 2010 showed a modest impact on OS, with a median improvement of 6 months. There was a more substantial effect on long term survivors with 2.6 fold increase of 5-yr OS. [Table: see text]

Radiosurgery for Acoustic Neuromas: Results of Low-dose Treatment

Neurosurgery ◽  
2003 ◽  
Vol 53 (2) ◽  
pp. 282-288 ◽  
Author(s):  
Yoshiyasu Iwai ◽  
Kazuhiro Yamanaka ◽  
Masato Shiotani ◽  
Taichi Uyama
Keyword(s):  
Tumor Growth ◽  
Low Dose ◽  
Tumor Resection ◽  
Gamma Knife Radiosurgery ◽  
Growth Control ◽  
Hearing Preservation ◽  
Trigeminal Neuropathy ◽  
Tumor Margin ◽  
Acoustic Neuromas

Abstract OBJECTIVE The results of radiosurgical treatment of acoustic neuromas have improved by reducing the tumor marginal doses. We report relatively long-term follow-up results (&gt;5 yr) for patients who underwent low-dose radiosurgery. METHODS We treated and followed 51 consecutive patients with unilateral acoustic neuromas who were treated from January 1994 to December 1996 by gamma knife radiosurgery at low doses (≤12 Gy to the tumor margin). The average age of the patients was 55 years (range, 32–76 yr). The treatment volume was 0.7 to 24.9 cm3 (median, 3.6 cm3). The marginal radiation dose was 8 to 12 Gy (median, 12 Gy), and the follow-up period ranged from 18 to 96 months (median, 60 mo). RESULTS Clinical tumor growth control (without tumor resection) was achieved in 96% of patients, and the 5-year tumor growth control rate was 92%. Hearing was preserved in 59% of those with preradiosurgical hearing preservation (Gardner-Robertson Classes 1–4), and improvements (&gt;20 dB of improvement) were noted in 9% of the patients with any hearing. Hearing was preserved at a useful level (Gardner-Robertson Classes 1 and 2) in 56% of patients. Although preexisting trigeminal neuropathy worsened in 4% of the patients, our patients did not experience new facial palsies or trigeminal neuropathies after radiosurgery. Facial spasm occurred in 6% of the patients, and intratumoral bleeding occurred in 4% of patients. CONCLUSION Low-dose radiosurgery (≤12 Gy at the tumor margin) can achieve a high tumor growth control rate and maintain low postradiosurgical morbidity (including hearing preservation) for acoustic neuromas.

Reduced-Dose Fractionated Stereotactic Radiotherapy for Acoustic Neuromas

Neurosurgery ◽  
2013 ◽  
Vol 73 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Colin E. Champ ◽  
Xinglei Shen ◽  
Wenyin Shi ◽  
Sonal U. Mayekar ◽  
Katherine Chapman ◽  
...  
Keyword(s):  
Stereotactic Radiotherapy ◽  
Hearing Preservation ◽  
Fractionated Stereotactic Radiotherapy ◽  
Symptom Improvement ◽  
Tumor Control ◽  
Noninvasive Treatment ◽  
Reduced Dose ◽  
Acoustic Neuromas ◽  
Cranial Nerve Dysfunction

Abstract BACKGROUND: Fractionated stereotactic radiotherapy (FSRT) is a noninvasive treatment for acoustic neuromas (ANs). Initial reports from our institution demonstrated that the reduction of treatment dose to 46.8 Gy resulted in improved preservation of functional hearing status. OBJECTIVE: We now report the tumor control (TC), symptomatic outcome, and hearing preservation (HP) rate in patients treated with reduced-dose FSRT. METHODS: We analyzed all patients with AN treated from 2002 to 2011. All patients received 46.8 Gy in 1.8-Gy fractions. Follow-up audiogram and magnetic resonance imaging were performed in ⩽1-year intervals. TC and HP were calculated by the Kaplan-Meier method. Analysis of HP, defined as Gardner-Robertson value ⩽2, was determined by audiometric data. Non-hearing-related symptoms were defined by Common Terminology Criteria for Adverse Events version 4. RESULTS: In total, 154 patients were analyzed. At a median follow-up of 35 months (range, 4-108), TC was achieved in 96% of patients (n = 148/154) and at 3 and 5 years was 99% and 93%. Eighty-seven patients had serviceable hearing at the time of FSRT and evaluable audiometric follow-up. Overall HP was 67% and at 3 and 5 years was 66% and 54%. Pure tone average decreased by a median of 13 dB in all patients. Nineteen percent (n = 31) of patients experienced symptom improvement, and 8% (n = 13) had worsening of symptoms. Cranial nerve dysfunction occurred in 3.8% of patients (n = 6). CONCLUSION: Reduced-dose FSRT to 46.8 Gy for AN achieves excellent functional HP rates and limited toxicity without compromising long-term TC. Based on these promising outcomes, further attempts at dose deescalation may be warranted.

Facial Nerve Outcomes After Vestibular Schwannoma Microsurgical Resection in Neurofibromatosis Type 2

2020 ◽  
pp. 019459982095414
Author(s):  
Catherine Sobieski ◽  
Daniel E. Killeen ◽  
Samuel L. Barnett ◽  
Bruce E. Mickey ◽  
Jacob B. Hunter ◽  
...  
Keyword(s):  
Facial Nerve ◽  
Vestibular Schwannoma ◽  
Tumor Volume ◽  
Tumor Resection ◽  
Neurofibromatosis Type ◽  
Neurofibromatosis Type 2 ◽  
Tumor Diameter ◽  
Microsurgical Resection

Objective The aim of this study is to investigate facial nerve outcomes after microsurgical resection in neurofibromatosis type 2 (NF2) compared to sporadic tumors. Study Design Single institutional retrospective chart review. Setting Tertiary referral center. Methods All adult patients with NF2 vestibular schwannoma (VS) or sporadic VS who underwent microsurgical resection from 2008 to 2019 with preoperative magnetic resonance imaging (MRI) and 1 year of postsurgical follow-up were included. The primary outcome measure was postoperative House-Brackmann (HB) facial nerve score measured at first postoperative visit and after at least 10 months. Results In total, 161 sporadic VSs and 14 NF2 VSs met inclusion criteria. Both median tumor diameter (NF2, 33.5 mm vs sporadic, 24 mm, P = .0011) and median tumor volume (NF2, 12.4 cm3 vs sporadic, 2.9 cm3, P = .0005) were significantly greater in patients with NF2. The median follow-up was 24.9 months (range, 12-130.1). Median facial nerve function after 1 year for patients with NF2 was HB 3 (range, 1-6) compared to HB 1 (range, 1-6) for sporadic VS ( P = .001). With multivariate logistic regression, NF2 tumors (odds ratio [OR] = 13.9, P = .001) and tumor volume ≥3 cm3 (OR = 3.6, P = .025) were significantly associated with HB ≥3 when controlling for age, sex, extent of tumor resection, translabyrinthine approach, and prior radiation. Conclusion Tumor volume >3 cm3 and NF2 tumors are associated with poorer facial nerve outcomes 1 year following microsurgical resection.

scholarly journals Long-term outcome after Gamma Knife radiosurgery for acoustic neuroma of all Koos grades: a single-center study

2019 ◽  
Vol 130 (2) ◽  
pp. 388-397 ◽  
Author(s):  
Josa M. Frischer ◽  
Elise Gruber ◽  
Verena Schöffmann ◽  
Adolf Ertl ◽  
Romana Höftberger ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Acoustic Neuroma ◽  
Gamma Knife Radiosurgery ◽  
Hearing Preservation ◽  
Tumor Control ◽  
Long Term Outcome ◽  
Acoustic Neuromas ◽  
Long Term Follow Up

OBJECTIVEThe authors present long-term follow-up data on patients treated with Gamma Knife radiosurgery (GKRS) for acoustic neuroma.METHODSSix hundred eighteen patients were radiosurgically treated for acoustic neuroma between 1992 and 2016 at the Department of Neurosurgery, Medical University Vienna. Patients with neurofibromatosis and patients treated too recently to attain 1 year of follow-up were excluded from this retrospective study. Thus, data on 557 patients with spontaneous acoustic neuroma of any Koos grade are presented, as are long-term follow-up data on 426 patients with a minimum follow-up of 2 years. Patients were assessed according to the Gardner-Robertson (GR) hearing scale and the House-Brackmann facial nerve function scale, both prior to GKRS and at the times of follow-up.RESULTSFour hundred fifty-two patients (81%) were treated with radiosurgery alone and 105 patients (19%) with combined microsurgery-radiosurgery. While the combined treatment was especially favored before 2002, the percentage of cases treated with radiosurgery alone has significantly increased since then. The overall complication rate after GKRS was low and has declined significantly in the last decade. The risk of developing hydrocephalus after GKRS increased with tumor size. One case (0.2%) of malignant transformation after GKRS was diagnosed. Radiological tumor control rates of 92%, 91%, and 91% at 5, 10, and 15 years after GKRS, regardless of the Koos grade or pretreatment, were observed. The overall tumor control rate without the need for additional treatment was even higher at 98%. At the last follow-up, functional hearing was preserved in 55% of patients who had been classified with GR hearing class I or II prior to GKRS. Hearing preservation rates of 53%, 34%, and 34% at 5, 10, and 15 years after GKRS were observed. The multivariate regression model revealed that the GR hearing class prior to GKRS and the median dose to the cochlea were independent predictors of the GR class at follow-up.CONCLUSIONSIn small to medium-sized spontaneous acoustic neuromas, radiosurgery should be recognized as the primary treatment at an early stage. Although minimizing the cochlear dose seems beneficial for hearing preservation, the authors, like others before, do not recommend undertreating intracanalicular tumors in favor of low cochlear doses. For larger acoustic neuromas, radiosurgery remains a reliable management option with tumor control rates similar to those for smaller acoustic neuromas; however, careful patient selection and counseling are recommended given the higher risk of side effects. Microsurgery must be considered in acoustic neuromas with significant brainstem compression or hydrocephalus.

Long-term tumor control and cranial nerve outcomes following Gamma Knife surgery for larger-volume vestibular schwannomas

2012 ◽  
Vol 116 (3) ◽  
pp. 598-604 ◽  
Author(s):  
Brian D. Milligan ◽  
Bruce E. Pollock ◽  
Robert L. Foote ◽  
Michael J. Link
Keyword(s):  
Posterior Fossa ◽  
Gamma Knife ◽  
Cranial Nerve ◽  
Tumor Volume ◽  
Gamma Knife Surgery ◽  
Tumor Control ◽  
Tumor Diameter ◽  
Tumor Margin ◽  
Median Maximum

Object Gamma Knife surgery (GKS) for vestibular schwannoma (VS) is an accepted treatment for small- to medium-sized tumors, generally smaller than 2.5 cm in the maximum posterior fossa dimension. The purpose of this study was to evaluate the efficacy and toxicity of GKS for larger tumors. Methods Prospectively collected data were analyzed for 22 patients who had undergone GKS for VSs larger than 2.5 cm in the posterior fossa diameter between 1997 and 2006. No patient had symptomatic brainstem compression at the time of GKS. The median treated tumor volume was 9.4 cm3 (range 5.3–19.1 cm3). The median maximum posterior fossa diameter was 2.8 cm (range 2.5–3.8 cm). The median tumor margin dose was 12 Gy (range 12–14 Gy). Serial imaging, audiometry (10 patients with serviceable hearing pre-GKS), and clinical follow-up were available for a median of 66 months (range 26–121 months). Tumor control failure was defined as either a progressive increase in tumor diameter of at least 2 mm in any dimension or a later resection. Results Four patients met the criteria for GKS failure, including 1 patient who demonstrated sarcomatous degeneration more than 7 years after GKS and died 3 months after microsurgical debulking. An enlarging cystic component was the surgical indication in 1 of the 2 patients who required resection, although 27% of tumors (6 lesions) were cystic before GKS. The 3-year actuarial rate of tumor control, freedom from new facial neuropathy, and preservation of functional hearing were 86%, 92%, and 47%, respectively. At 5 years post-GKS, these rates decreased to 82%, 85%, and 28%, respectively. At the most recent follow-up, 91% of tumors were smaller than at the time of GKS and the median maximum posterior fossa diameter reduction was 26%. On multivariate analysis, none of the following factors was associated with GKS failure, new facial weakness, new trigeminal neuropathy, or loss of serviceable hearing: patient age, tumor volume, tumor margin dose, and preoperative cranial nerve dysfunction. Conclusions Single-session radiosurgery is a successful treatment for the majority of patients with larger VSs. Although tumor control rates are lower than those for smaller VSs managed with GKS, the cranial nerve morbidity of GKS is significantly lower than that typically achieved via resection of larger VSs.

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