Gamma knife surgery for patients with volumetric classification of nonfunctioning pituitary adenomas: a systematic review and meta-analysis

ObjectiveThe aim of this study was to scrutinize the literature to determine the efficacy and safety of gamma knife surgery (GKS) for the treatment of nonfunctioning pituitary adenomas (NFPAs) with volumetric classification.MethodsElectronic databases including MedLine, PubMed, and Cochrane Central were searched. The literature related to patients with NFPAs treated with GKS was collected. Eligible studies reported on the rate of tumor control (RTC), the rate of radiosurgery-induced optic neuropathy injury (RRIONI), the rate of radiosurgery-induced endocrinological deficits (RRIED), and other parameters.ResultsA total of 17 studies met the criteria. Based on the tumor volume, NFPAs were divided into three groups: the RTC of group I (93 patients) with tumor volumes <2 ml was 99% (95% CI 96–100%), the RRIONI was 1% (95% CI 0–4%), and the RRIED was 1% (95% CI 0–4%). The RTC of group II (301 patients) with volumes from 2 to 4 ml was 96% (95% CI 92–99%), the RRIONI was 0 (95% CI 0–2%), and RRIED was 7% (95% CI 2–14%). The RTC of group III (531 patients) with volumes larger than 4 ml was 91% (95% CI 89–94%), the RRIONI was 2% (95% CI 0–5%), and the RRIED was 22% (95% CI 14–31%). There were significant differences in the RTC and in the RRIED among the three groups (P<0.001), indicating that there were higher RRIED and lower RTC with the increase of tumor volume.ConclusionsNFPAs, according to tumor volume classification, need stratification for GKS treatment. GKS is the optimal choice for the treatment of group II NFPAs. Patients with residual tumor volumes of <4 ml will benefit most from GKS treatment.

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Radiosurgery for nonfunctioning pituitary adenoma

Neurosurgical FOCUS ◽

10.3171/foc.2003.14.5.10 ◽

2003 ◽

Vol 14 (5) ◽

pp. 1-6 ◽

Cited By ~ 16

Author(s):

Jason P. Sheehan ◽

Douglas Kondziolka ◽

John Flickinger ◽

L. Dade Lunsford

Keyword(s):

Gamma Knife ◽

Treatment Modality ◽

Pituitary Adenomas ◽

Pituitary Tumors ◽

Primary Treatment ◽

Gamma Knife Surgery ◽

Tumor Control ◽

Cavernous Sinus Invasion ◽

Nonfunctioning Pituitary Adenomas ◽

Primary Treatment Modality

Object Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study was to evaluate the efficacy and role of gamma knife surgery (GKS) in the treatment of these lesions. Methods The authors conducted a review of cases in which GKS was performed at the University of Pittsburgh between 1987 and 2001. Forty-six patients with nonfunctioning pituitary adenomas and with at least 6 months of follow-up data were identified. In 41 of these patients some form of prior treatment such as transsphenoidal resection, craniotomy and resection, or conventional radiation therapy had been conducted. Five patients were deemed ineligible for microsurgery, and GKS served as the primary treatment modality. Endocrinological, ophthalmological, and radiological responses were evaluated. The mean radiation dose to the margin was 16 Gy. In all patients with microadenomas and 91% of those with macroadenomas tumor control was demonstrated after radiosurgery. Gamma knife surgery had essentially equal efficacy in terms of achieving tumor control in cases of adenomas with cavernous sinus invasion and suprasellar extension. No new endocrinopathies were noted following radiosurgery. In two patients, however, tumor growth and decline in visual function occurred. Conclusions Gamma knife surgery is safe and effective in treating nonfunctioning pituitary adenomas. Radiosurgery may serve as a primary treatment modality in some or as a salvage treatment in others. Treatment must be tailored to meet the patient's symptoms, overall health, and tumor morphometry.

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Combination of microsurgery and Gamma Knife surgery for the treatment of intracranial chondrosarcomas

Journal of Neurosurgery ◽

10.3171/sup.2006.105.7.18 ◽

2006 ◽

Vol 105 (Supplement) ◽

pp. 18-25 ◽

Cited By ~ 13

Author(s):

Petter Förander ◽

Tiit Rähn ◽

Lars Kihlström ◽

Elfar Ulfarsson ◽

Tiit Mathiesen

Keyword(s):

Gamma Knife ◽

Cranial Nerve ◽

Residual Tumor ◽

Local Tumor Control ◽

Gamma Knife Surgery ◽

Long Term Results ◽

Tumor Control ◽

Low Grade ◽

Cranial Nerve Palsies ◽

Tumor Volume Reduction

ObjectIntracranial chondrosarcomas have a high risk of recurrence after surgery. This retrospective study of patients with intracranial chondrosarcoma was conducted to determine the long-term results of microsurgery followed by Gamma Knife surgery (GKS) for residual tumor or recurrence.MethodsThe authors treated nine patients whose median age was 36 years. Seven patients had low-grade chondrosarcomas (LGCSs), whereas mesenchymal chondrosarcomas (MCSs) were diagnosed in two. Radiosurgery was performed in eight patients, whereas one patient declined further surgical intervention and tumor-volume reduction necessary for the GKS.The patients were followed up for 15 to 173 months (median 108 months) after diagnosis and 3 to 166 months (median 88 months) after GKS. Seven patients had residual tumor tissue after microsurgery, and two operations appeared radical. In the two latter cases, tumors recurred after 25 and 45 months. Thus, definite tumor control was not achieved after surgery alone in any patient, whereas the addition of radiosurgery allowed tumor control in all six patients with LGCSs. Two of these patients experienced an initial tumor regrowth after GKS; in both cases the recurrences were outside the prescribed radiation field. The patients underwent repeated GKS, and subsequent tumor control was observed. An MCS was diagnosed in the remaining two patients. Complications after microsurgery included diplopia, facial numbness, and paresis. After GKS, one patient had radiation necrosis, which required microsurgery, and two patients had new cranial nerve palsies.Conclusions Tumor control after microsurgery alone was not achieved in any patient, whereas adjuvant radiosurgery provided local tumor control in six of eight GKS-treated patients. Tumor control was not achieved in the two patients with MCS. Similar to other treatments for intracranial chondrosarcoma, morbidity after micro- and radiosurgical combination therapy was high and included severe cranial nerve palsies.

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Gamma Knife surgery for invasive pituitary macroadenoma

Journal of Neurosurgery ◽

10.3171/sup.2006.105.7.26 ◽

2006 ◽

Vol 105 (Supplement) ◽

pp. 26-30 ◽

Cited By ~ 10

Author(s):

Mooseong Kim ◽

Sunghwa Paeng ◽

Seyoung Pyo ◽

Yeonggyun Jeong ◽

Sunil Lee ◽

...

Keyword(s):

Gamma Knife ◽

Cavernous Sinus ◽

Pituitary Adenomas ◽

Gamma Knife Surgery ◽

Tumor Control ◽

Pituitary Macroadenoma ◽

Female Ratio ◽

Fractionated Radiotherapy ◽

The Mean

ObjectPituitary adenomas have been treated using a variety of modalities including resection, medication, fractionated radiotherapy, and stereotactic radiosurgery. The policy has been that all adenomas should first be treated with resection to reduce the volume of the tumor. The authors' study was conducted to determine the efficacy of using Gamma Knife surgery (GKS) for pituitary adenomas invading the cavernous sinus.MethodsOf 397 patients with pituitary tumors who underwent GKS between October 1994 and October 2005, 68 patients had pituitary macroadenomas invading the cavernous sinus. Sixty-seven cases were available for follow up. The mean age of the patients in these cases was 42.8 years (range 14–73 years). The male/female ratio was 0.8:1. The mean adenoma volume was 9.3 cm3. A total of 24 patients had undergone craniotomies and resection, and 11 patients had undergone transsphenoidal surgery prior to GKS. The mean follow-up period was 32.8 months. Tumor control was defined as a decrease or no change in tumor volume after GKS. Endocrinological improvement was defined as a decline in hormone levels to below 50% of the pre-GKS level.Tumor control was achieved in 95.5% of the cases. Endocrinological improvement was achieved in 68% of 25 patients. One patient suffered hypopituitarism after GKS.Conclusions Gamma Knife surgery is a safe and effective treatment for invasive pituitary macroadenoma with few complications.

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Characteristic of Tumor Regrowth After Gamma Knife Radiosurgery and Outcomes of Repeat Gamma Knife Radiosurgery in Nonfunctioning Pituitary Adenomas

Frontiers in Oncology ◽

10.3389/fonc.2021.627428 ◽

2021 ◽

Vol 11 ◽

Author(s):

Yanli Li ◽

Lisha Wu ◽

Tingting Quan ◽

Junyi Fu ◽

Linhui Cao ◽

...

Keyword(s):

Gamma Knife ◽

Key Management ◽

Pituitary Adenomas ◽

Gamma Knife Radiosurgery ◽

Tumor Control ◽

Nonfunctioning Pituitary Adenomas ◽

Independent Risk Factors ◽

Tumor Regrowth ◽

Design And Methods

ObjectiveThis study aimed to report the characteristic of tumor regrowth after gamma knife radiosurgery (GKRS) and outcomes of repeat GKRS in nonfunctioning pituitary adenomas (NFPAs).Design and MethodsThis retrospective study consisted of 369 NFPA patients treated with GKRS. The median age was 45.2 (range, 7.2–84.0) years. The median tumor volume was 3.5 (range, 0.1–44.3) cm3.ResultsTwenty-four patients (6.5%) were confirmed as regrowth after GKRS. The regrowth-free survivals were 100%, 98%, 97%, 86% and 77% at 1, 3, 5, 10 and 15 year, respectively. In multivariate analysis, parasellar invasion and margin dose (<12 Gy) were associated with tumor regrowth (hazard ratio [HR] = 3.125, 95% confidence interval [CI] = 1.318–7.410, p = 0.010 and HR = 3.359, 95% CI = 1.347–8.379, p = 0.009, respectively). The median time of regrowth was 86.1 (range, 23.2–236.0) months. Previous surgery was associated with tumor regrowth out of field (p = 0.033). Twelve patients underwent repeat GKRS, including regrowth in (n = 8) and out of field (n = 4). Tumor shrunk in seven patients (58.3%), remained stable in one (8.3%) and regrowth in four (33.3%) with a median repeat GKRS margin dose of 12 (range, 10.0–14.0) Gy. The actuarial tumor control rates were 100%, 90%, 90%, 68%, and 68% at 1, 3, 5, 10, and 15 years after repeat GKRS, respectively.ConclusionsParasellar invasion and tumor margin dose (<12 Gy) were independent risk factors for tumor regrowth after GKRS. Repeat GKRS might be effective on tumor control for selected patients. For regrowth in field due to relatively insufficient radiation dose, repeat GKRS might offer satisfactory tumor control. For regrowth out of field, preventing regrowth out of field was the key management. Sufficient target coverage and close follow-up might be helpful.

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Effectiveness of a 1-day aspiration plus Gamma Knife surgery procedure for metastatic brain tumor with a cystic component

Journal of Neurosurgery ◽

10.3171/2012.7.gks121001 ◽

2012 ◽

Vol 117 (Special_Suppl) ◽

pp. 17-22 ◽

Cited By ~ 13

Author(s):

Fumi Higuchi ◽

Shunsuke Kawamoto ◽

Yoshihiro Abe ◽

Phyo Kim ◽

Keisuke Ueki

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Gamma Knife Surgery ◽

Tumor Control ◽

Efficient Treatment ◽

Stereotactic Aspiration ◽

Stereotactic Frame ◽

Cystic Component ◽

Tumor Volume Reduction ◽

Good Tumor Control

Object Gamma Knife surgery (GKS) has gained increasing relevance in the treatment of metastatic brain tumors, but many metastatic tumors contain a large cystic component and often exceed the size limit for GKS. For such lesions, the authors adopted a procedure in which stereotactic aspiration is first performed and followed immediately by GKS on the same day. In this paper, the authors describe this 1-day combined procedure and evaluate its efficacy. Methods Between 2005 and 2010, 25 cystic metastases in 25 patients were treated at Dokkyo Medical University. The patients first underwent MRI and stereotactic aspiration of the cyst while stationary in a Leksell stereotactic frame; immediately afterward, the patients underwent a second MR imaging session and Gamma Knife treatment. Tumor volume reduction, tumor control rate, and overall survival were examined. Results Tumor volume, including the cystic component, decreased from 8.0–64.2 cm3 (mean 20.3 cm3) to 3.0–36.2 cm3 (mean 10.3 cm3) following aspiration, and the volume of 24 of 25 lesions decreased to less than 16.6 cm3, which is equivalent to the volume of a 3.16-cm sphere. At least 20 Gy was delivered to the entire lesion in 24 of 25 cases. Good tumor control was obtained in 16 of 21 cases that could be evaluated during a median follow-up period of 11 months (range 1–27 months); however, reaccumulation of cyst contents was observed in 2 patients who required Ommaya reservoir placement. Conclusions The 1-day aspiration plus GKS procedure is an effective and time-efficient treatment for large cystic brain metastases.

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Volume reduction in meningiomas after gamma knife surgery

Journal of Neurosurgery ◽

10.3171/jns.2005.102.s_supplement.0189 ◽

2005 ◽

Vol 102 ◽

pp. 189-194 ◽

Cited By ~ 26

Author(s):

Guenther C. Feigl ◽

Otto Bundschuh ◽

Alireza Gharabaghi ◽

Madjid Samii ◽

Gerhard A. Horstmann

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Gamma Knife Surgery ◽

Volume Reduction ◽

World Health ◽

Tumor Control ◽

Content Type ◽

The Mean ◽

Fine Print

Object.The purpose of this study was to evaluate the volume-reducing effects of gamma knife surgery (GKS) of meningiomas with and without previous surgical treatment.Methods.A group of 127 patients with a mean age of 57.1 years (range 9–81 years) with 142 meningiomas (128 World Health Organization Grade I and 14 Grade II) were included in this study. The management strategy reduces tumor volume with surgery when necessary (81 patients). Stereotactic GKS with a Gamma Knife model C was performed in all tumors of suitable size. Magnetic resonance imaging follow-up examinations with volumetric tumor analysis was performed 6 months after treatment and annually thereafter.The mean tumor volume was 5.9 cm3(range < 5 to > 40 cm3). The mean follow-up time after GKS was 29.3 months (range 11–61 months). The mean prescription dose was 13.8 Gy (range 10–18 Gy). A reduction in volume occurred in 117 (82.4%) of all tumors, and in 20 tumors (14.1%) growth ceased. The overall tumor control rate of 96.4%. The mean volume reduction achieved with GKS was more than 46.1%. Only five tumors (3.5%) showed a volume increase.Conclusions.Gamma knife surgery was effective in reducing meningioma volume at short-term follow up. Further studies are needed to examine the development of these findings over a longer period.

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Gamma Knife surgery for patients with brainstem metastases

Journal of Neurosurgery ◽

10.3171/2012.7.gks12977 ◽

2012 ◽

Vol 117 (Special_Suppl) ◽

pp. 23-30 ◽

Cited By ~ 19

Author(s):

Takuya Kawabe ◽

Masaaki Yamamoto ◽

Yasunori Sato ◽

Bierta E. Barfod ◽

Yoichi Urakawa ◽

...

Keyword(s):

Gamma Knife ◽

Tumor Volume ◽

Recursive Partitioning ◽

Survival Rates ◽

Gamma Knife Surgery ◽

Tumor Control ◽

Karnofsky Performance Scale ◽

Radical Cure ◽

Class Iii ◽

Meningeal Dissemination

Object Because brainstem metastases are not deemed resectable, stereotactic radiosurgery (SRS) is the only treatment modality expected to achieve a radical cure. The authors describe their treatment results, focusing particularly on how long patients can survive without neurological deterioration following SRS for brainstem metastases. Methods This was an institutional review board–approved, retrospective cohort study in which the authors pulled from their database information on 2553 consecutive patients with brain metastases who underwent Gamma Knife surgery (GKS) at the Mito GammaHouse between July 1998 and July 2011. Among the 2553 patients, excluding cases in which there was meningeal dissemination, 200 cases of brainstem metastases (78 women and 122 men with a mean age of 64 years [range 36–86 years]) were identified and analyzed. The most common primary site was the lung (137 patients) followed by the gastrointestinal tract (24 patients), breast (17 patients), kidney (12 patients), and others (10 patients). Among the 200 patients, 15 patients (7.5%) harbored at least 2 tumors in the brainstem: 11 patients had 2 tumors, 2 patients had 3 tumors, and 1 patient each had 4 or 5 tumors. Therefore, a total of 222 tumors were irradiated. These 222 tumors were located in the pons (121 lesions), the midbrain (65 lesions), and the medulla oblongata (36 lesions). The mean and median tumor volumes were 1.3 and 0.2 cm3 (range 0.005–10.7 cm3), and the median peripheral radiation dose was 18.0 Gy (range 12.0–25.0 Gy). Results The overall median survival time (MST) was 6.0 months. Distribution of MSTs across Recursive Partitioning Analysis (RPA) classes showed that the MSTs were 9.4 months in Class I (20 patients), 6.0 months in Class II (171 patients), and 1.9 months in Class III (9 patients). Better Karnofsky Performance Scale score, single metastasis, and well-controlled primary tumor were significant predictive factors for longer survival. The neurological and qualitative survival rates were 90.8% and 89.2%, respectively, at 24 months post-GKS. Better KPS score and smaller tumor volume tended to be associated with prolonged qualitative survival. Follow-up imaging studies were available for 129 patients (64.5%). The tumor control rate was 81.8% at 24 months post-GKS. Smaller tumor volume tended to contribute to tumor control. Conclusions The present results indicate that GKS is effective in the treatment of brainstem metastases, particularly from the viewpoint of maintaining a good neurological condition in the patient.

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Evaluation of Fractionated Radiotherapy and Gamma Knife Radiosurgery in Cavernous Sinus Meningiomas: Treatment Strategy

Neurosurgery ◽

10.1227/01.neu.0000179924.76551.cd ◽

2005 ◽

Vol 57 (5) ◽

pp. 873-886 ◽

Cited By ~ 84

Author(s):

Philipe Metellus ◽

Jean Regis ◽

Xavier Muracciole ◽

Stephane Fuentes ◽

Henry Dufour ◽

...

Keyword(s):

Gamma Knife ◽

Cavernous Sinus ◽

Treatment Strategy ◽

Gamma Knife Radiosurgery ◽

Tumor Control ◽

Fractionated Radiotherapy ◽

Group I ◽

Group Ii

Abstract OBJECTIVE: To investigate the respective role of fractionated radiotherapy (FR) and gamma knife stereotactic (GKS) radiosurgery in cavernous sinus meningioma (CSM) treatment. METHODS: The authors report the long-term follow-up of two populations of patients harboring CSMs treated either by FR (Group I, 38 patients) or GKS radiosurgery (Group II, 36 patients). There were 31 females with a mean age of 53 years in Group I and 29 females with a mean age of 51.2 years in Group II. In 20 patients (Group I) and 13 patients (Group II), FR and GKS radiosurgery were performed as an adjuvant treatment. In 18 patients (Group I) and in 23 patients (Group II), FR and GKS radiosurgery were performed as first line treatment. In our early experience with GKS radiosurgery (1992, date of gamma knife availability in the department), patients with tumors greater than 3 cm, showing close relationship with the optic apparatus (<3 mm) or skull base dural spreading, were treated by FR. Secondarily, with the advent of new devices and our growing experience, these criteria have evolved. RESULTS: The median follow-up period was 88.6 months (range, 42–168 mo) for Group I and 63.6 months (range, 48–92 mo) for Group II. According to Sekhar's classification, 26 (68.4%) patients were Grade III to IV in Group I and 10 (27.8%) patients in Group II (P < 0.05); 23 (60.5%) patients had extensive lesions in Group I and 7 (19.4%) patients in Group II (P < 0.05). Mean tumor volume was 13.5 cm3 in Group I and 5.2 cm3 in Group II (P < 0.05). Actuarial progression-free survival was 94.7% and 94.4% in Group I and II, respectively. Clinically, improvement was seen for 24 (63.2%) patients in Group I and for 21 (53.8%) patients in Group II (P > 0.05). Radiologically, 11 (29%, Group I) patients and 19 (Group II, 52.7%) patients showed tumor shrinkage (P = 0.04). Transient morbidity was 10.5% in Group I and 2.8% in Group II. Permanent morbidity was 2.6% in Group I and 0% in Group II. CONCLUSION: FR and GKS radiosurgery are safe and efficient techniques in treatment of CSMs, affording comparable satisfactory long-term tumor control. However, GKS radiosurgery provides better radiological response, is far more convenient, and fits into most patients lives much better than FR. Therefore, in the authors' opinion, GKS radiosurgery should be advocated in first intention for patients with CSMs, whereas conventional radiotherapy should be reserved for cases that are not amenable to this technique, thus making these two therapeutic modalities not alternative but complementary tools in CS meningioma treatment strategy.

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

Journal of Neurosurgery ◽

10.3171/2011.11.jns11811 ◽

2012 ◽

Vol 116 (3) ◽

pp. 598-604 ◽

Cited By ~ 56

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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Gamma Knife surgery for skull base chordomas and chondrosarcomas

Journal of Neurosurgery ◽

10.3171/jns-07/10/0752 ◽

2007 ◽

Vol 107 (4) ◽

pp. 752-757 ◽

Cited By ~ 69

Author(s):

Toshinori Hasegawa ◽

Dai Ishii ◽

Yoshihisa Kida ◽

Masayuki Yoshimoto ◽

Joji Koike ◽

...

Keyword(s):

Skull Base ◽

Gamma Knife ◽

Tumor Volume ◽

Tumor Resection ◽

Gamma Knife Surgery ◽

High Rate ◽

Tumor Control ◽

Low Grade ◽

The Mean ◽

Skull Base Chordomas

Object The purpose of this study was to evaluate radiosurgical outcomes in skull base chordomas and chondrosarcomas, and to determine which tumors are appropriate for stereotactic radiosurgery as adjuvant therapy following maximum tumor resection. Methods Thirty-seven patients (48 lesions) were treated using Gamma Knife surgery (GKS); 27 had chordomas, seven had chondrosarcomas, and three had radiologically diagnosed chordomas. The mean tumor volume was 20 ml, and the mean maximum and marginal doses were 28 and 14 Gy, respectively. The mean follow-up period was 97 months from diagnosis and 59 months from GKS. Results The actuarial 5- and 10-year survival rates after GKS were 80 and 53%, respectively. The actuarial 5- and 10-year local tumor control (LTC) rates after single or multiple GKS sessions were 76 and 67%, respectively. All patients with low-grade chondrosarcomas achieved good LTC. A tumor volume of less than 20 ml significantly affected the high rate of LTC (p = 0.0182). No patient had adverse radiation effects, other than one in whom facial numbness worsened despite successful tumor control. Conclusions As an adjuvant treatment after resection, GKS is a reasonable option for selected patients harboring skull base chordomas or chondrosarcomas with a residual tumor volume of less than 20 ml. Dose planning with a generous treatment volume to avoid marginal treatment failure should be made at a marginal dose of at least 15 Gy to achieve long-term tumor control.

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