Fractionated stereotactic radiotherapy in craniopharyngiomas: A systematic review and single arm meta-analysis

INTRODUCTION

Numerous studies have demonstrated Fractionated Stereotactic Radiotherapy's (FSRT) effectiveness in tumor control post-resection for craniopharyngiomas. Nevertheless, past literature has presented conflicting findings particularly regarding endocrine and visual function outcomes. This study aims to elucidate FSRT's efficacy and safety for this population.

METHODS

Adhering to PRISMA, a systematic review and meta-analyses was conducted. Included studies had to report the effects of FSRT for treating craniopharyngiomas in a sample greater than four patients, addressing at least one of the outcomes of interest: improvement in visual acuity or field, new-onset hypopituitarism, effectiveness, and tumor progression. Relative risk with 95% confidence intervals were used to assess the outcomes.

RESULTS

After retrieving a total of 1292 studies, 10 articles met the predefined criteria and thus were finally selected, amounting to a total of 256 patients. The improvement in visual acuity was estimated at 45% (95% CI: 6-83%), while the improvement in the visual field was 22% (95% CI: 0-51%). Regarding endocrine function, the new-onset hypopituitarism rate was found to be 5% (95% CI: 0-11%). Relative to FSRT effectiveness, the pooled estimate of the complete tumor response rate was 17% (95% CI: 4-30%), and the tumor progression rate was 7% (95% CI: 1-13%). Also, a 3-year progression-free survival rate of 98% (95% CI: 95-100%) was obtained.

CONCLUSION

Despite limitations and risks, FSRT shows promise as a viable therapeutic option for craniopharyngiomas, offering notable benefits for visual functions and tumor control. Further research is required to better understand the associated risks, benefits, and clinical utility.

Stereotactic radiosurgery of brain metastases: a retrospective study

BACKGROUND

Single-fraction stereotactic radiosurgery (SRS) is an established standard for radiation therapy of brain metastases although recent developments indicate that multi-fractionated stereotactic radiotherapy (FSRT) results in lower radiation necrosis especially for larger metastases, and the same or even better local control in comparison to SRS.

METHODS

Seventy-two patients with 111 brain metastases received SRS with a single dose of 18 Gy between September 2014 and December 2021. The dose prescription was either 18 Gy given to the enclosing 80% isodose with a normalization to Dmax = 100% of 22.5 Gy (part I) or 18 Gy = D98, while D0.03 cc of 21.6-22.5 Gy was accepted (part II). The study retrospectively evaluated local progression-free survival (LPFS), response on the first follow-up magnetic resonance imaging (MRI), and radiation necrosis.

RESULTS

Melanoma brain metastases (n = 44) were the most frequent metastases. The median gross tumor volume (GTV) was 0.30 cm³ (IQR, 0.17-0.61). The median follow-up time of all patients was 50.8 months (IQR, 30.4-64.6). Median LPFS was 23.5 months (95%CI 17.2, 29.8). The overall LPFS rates at 12-, 18-, 24- and 30 months were 65.3%, 56.3%, 46.5%, and 38.8%. Brain metastases with radioresistant histology (melanoma, renal cell cancer, and sarcoma) showed a 12-month LPFS of 60.2%, whereas brain metastases with other histology had a 12-month LPFS of 70.1%. The response of brain metastases on first follow-up MRIs performed after a median time of 47 days (IQR, 40-63) was crucial for long-term local control and survival. Eight brain metastases (7.2%) developed radiation necrosis after a median time of 18.4 months (IQR, 9.4-26.5). In multivariate analyses, a GTV > 0.3 cm³ negatively affected LPFS (HR 2.229, 95%CI 1.172, 4.239). Melanoma, renal cell cancers, and sarcoma had a lower chance of LPFS in comparison to other cancer types (HR 2.330, 95%CI 1.155, 4.699).

CONCLUSIONS

Our results indicate a reasonable 1-year local control of brain metastases with radiosensitive histology. Radioresistant metastases show a comparatively poor local control. Treatment refinements merit exploration to improve local control of brain metastases.

TRIAL REGISTRATION

This study is retrospectively registered (ethics approval number 23-3451-104).

Comparison of Staged Stereotactic Radiosurgery and Fractionated Stereotactic Radiotherapy in Patients with Brain Metastases > 2 cm without Prior Whole Brain Radiotherapy: A Systematic Review and Meta-Analysis

OBJECTIVE

To compare fractionated stereotactic radiotherapy (FSRT) with staged stereotactic radiosurgery (SSRS) in patients with brain metastases >2 cm without prior whole brain radiotherapy.

METHODS

In this systematic review and meta-analysis, PubMed, Scopus, Web of Science, Embase, and Cochrane were searched to include studies that evaluated FSRT and/or SSRS for brain metastases >2 cm or 4 cm3 in adult patients with a known primary malignancy and no prior history of whole brain radiotherapy. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed and an indirect random-effect meta-analyses was conducted to compare treatment outcomes between the two modalities.

RESULTS

A total of 10 studies were included, comprising 612 (778 metastases) and 250 patients (265 metastases) in the SSRS and FSRT groups, respectively. The SSRS group had significantly older patients (66.6 ± 17.51 years vs. 62.37 ± 37.89 years; P = 0.029) with lower rate of control of primary disease (11.59% vs. 78.7%, P < 0.00001), and more patients with Karnofsky performance status ≥70 at baseline (92.81% vs. 88.56%; P = 0.045). FSRT was associated with a statistically nonsignificant but clinically important lower 12-month overall survival (44.75% [95% confidence interval [CI]: 30.48%-59.95%] vs. 53.25% [95%CI: 45.15%-61.19%], P = 0.1615) and higher rate of salvage radiotherapy (18.18% [95%CI: 8.75%-34%] vs. 12.27% [95%CI: 5.98%-23.53%], P = 0.0841). Both groups had comparable rates of local tumor control, mortality, tumor progression, recurrence, neurological death, and 6-month overall survival.

CONCLUSIONS

SSRS and FSRT were found to be comparable for treating brain metastases >2 cm not previously irradiated. Given the paucity of such studies, trials directly comparing the two treatment strategies are warranted to support these findings.

Treatment Outcomes After Higher-dose Fractionated Stereotactic Radiotherapy (FSRT) Alone for 1-4 Brain Metastases

BACKGROUND/AIM

Fractionated stereotactic radiotherapy (FSRT) is increasingly used for brain metastases. We investigated higher-dose FSRT with biologically effective doses (BED) of 49.6-66.7 Gy₁₂ Patients and Methods: Eleven characteristics were evaluated for local control (LC), overall survival (OS), and freedom from radiation necrosis (RN) in 69 patients with 1-4 brain metastases. Fifty-seven patients (83%) had extracranial metastases, 23 (33%) Karnofsky performance scores (KPS) ≤70, and 21 (30%) brain metastases ≥21 mm.

RESULTS

At 1 and 2 years, LC-rates were 81% and 63%, OS-rates 66% and 43%, and freedom from RN-rates 98% and 87%, respectively. Median time to local progression was 35 months, median survival 19 months. KPS ≥90 was associated with better OS (p=0.048). BED of 49.6-57 Gy₁₂ (vs. 63-66.7 Gy₁₂) was associated with higher rates of freedom from RN (p=0.046), not with LC (p=0.78) or OS (p=0.55).

CONCLUSION

Higher-dose FSRT appears feasible and effective in patients with 1-4 brain metastases. BED 63-66.7 Gy₁₂ may not improve LC and OS but may increase RN risk.

Fractionated stereotactic radiotherapy of brain metastases: results of a retrospective study

BACKGROUND

Lasting local control of brain metastases following stereotactic radiotherapy is becoming increasingly relevant since systemic treatment constantly improves the prognosis of patients with extracranial metastases.

METHODS

73 patients with 103 brain metastases received hypofractionated stereotactic radiotherapy (FSRT) in 6 fractions of 5 Gy between January 2017 and December 2021 at the University Hospital Regensburg, Germany. The study retrospectively evaluated local progression free survival (LPFS), overall survival (OS) and distant brain progression free survival (DPFS) of patients without prior radiotherapy of the brain. Response rate and brain radiation necrosis were reported. Cox proportional hazard models evaluated prognostic factors of OS and LPFS.

RESULTS

The median patient age was 61.0 years (Interquartile range, IQR 51.0, 67.5). The most common tumor types were malignant melanoma (34.2%) and non-small cell lung adenocarcinoma (26.0%). The median gross tumor volume (GTV) was 0.9 cm³ (IQR 0.4, 3.6). The median follow-up time of all patients was 36.3 months (95%CI 29.1, 43.4). The median OS was 17.4 months (95%CI 9.9, 24.9). Overall survival rates at 6-, 12-, 18-, 24-, and 30 months were 81.9%, 59.1%, 49.0%, 41.3%, and 37.2%, retrospectively. The mean LPFS was 38.1 months (95%CI 31.4, 44.9), while the median LPFS has not been reached. LPFS rates at 6-, 12-, 18-, 24- and 30 months were 78.9%, 68.7%, 64.3%, 61.6% and 58.7%, retrospectively. Median DPFS of all patients was 7.7 months (95%CI 6.1, 9.3). Six, 12-, 18-, 24- and 30 months DPFS rates were 62.1%, 36.3%, 31.1%, 24.8% and 21.7%. Five brain metastases (4.8%) developed brain radiation necrosis. In multivariate analysis, the number of brain metastases negatively affected LPFS. Non-melanoma and non-renal cell cancer was associated with a higher chance of LPFS in comparison to other cancer. A GTV > 1.5 cm³ translated into a higher risk of death compared to a GTV ≤ 1.5 cm³ and Karnofsky performance score was predictive of OS.

CONCLUSIONS

FSRT in 6 fractions of 5 Gy seems to be an effective treatment with an acceptable local control for patients with brain metastases although melanoma and renal cell cancer seem to have a worse local control in comparison to other cancer.

TRIAL REGISTRATION

This study is retrospectively registered.

Single fraction stereotactic radiosurgery and fractionated stereotactic radiotherapy provide equal prognosis with overall survival in patients with brain metastases at diagnosis without surgery at primary site

Background and purpose

Stereotactic radiosurgery (SRS) and fractionated stereotactic radiation therapy (SRT) are both treatments shown to be effective in treating brain metastases (BMs). However, it is unknown how these treatments compare in effectiveness and safety in cancer patients with BMs regardless of the primary cancer. The main objective of this study is to investigate the SRS and SRT treatments' associations with the overall survival (OS) of patients diagnosed with BMs using the National Cancer Database (NCDB).

Materials and methods

Patients in the NCDB with breast cancer, non-small cell lung cancer, small cell lung cancer, other lung cancers, melanoma, colorectal cancer, or kidney cancer who had BMs at the time of their primary cancer diagnosis and received either SRS or SRT as treatment for their BMs were included in the study. We analyzed OS with a Cox proportional hazard analysis that adjusted variables associated with improved OS during univariable analysis.

Results

Of the total 6,961 patients that fit the criteria for the study, 5,423 (77.9%) received SRS and 1,538 (22.1%) received SRT. Patients who received SRS treatment had a median survival time of 10.9 (95% CI [10.5-11.3]), and those who received SRT treatment had a median survival time of 11.3 (95% CI [10.4-12.3]) months. This difference was not found to be significant (Log-rank P = 0.31). Multivariable Cox proportional hazard analysis did not yield a significant difference between the treatments' associations with OS (Hazard Ratio: 0.942, CI 95% [0.882-1.006]; P = .08) or SRS vs. SRT.

Conclusions

In this analysis, SRS and SRT did not show a significant difference in their associations with OS. Future studies investigating the neurotoxicity risks of SRS as compared to SRT are warranted.

An exploratory analysis of MR-guided fractionated stereotactic radiotherapy in patients with brain metastases

Purpose

To assess the feasibility and potential benefits of online adaptive MR-guided fractionated stereotatic radiotherapy (FSRT) in patients with brain metastases (BMs).

Methods and materials

Twenty-eight consecutive patients with BMs were treated with FSRT of 30 Gy in 5 fractions on the 1.5 T MR-Linac. The FSRT fractions employed daily MR scans and the contours were utilized to create each adapted plan. The brain lesions and perilesional edema were delineated on MR images of pre-treatment simulation (Fx0) and all fractions (Fx1, Fx2, Fx3, Fx4 and Fx5) to evaluate the inter-fractional changes. These changes were quantified using absolute/relative volume, Dice similarity coefficient (DSC) and Hausdorff distance (HD) metrics. Planning target volume (PTV) coverage and organ at risk (OAR) constraints were used to compare non-adaptive and adaptive plans.

Results

A total of 28 patients with 88 lesions were evaluated, and 23 patients (23/28, 82.1%) had primary lung adenocarcinoma. Significant tumor volume reduction had been found during FSRT compared to Fx0 for all 88 lesions (median -0.75%, -5.33%, -9.32%, -17.96% and -27.73% at Fx1, Fx2, Fx3, Fx4 and Fx5, p < 0.05). There were 47 (47/88, 53.4%) lesions being accompanied by perilesional edema and the inter-fractional changes were significantly different compared to those without perilesional edema (p < 0.001). Patients with multiple lesions (13/28, 46.4%) had more significant inter-fractional tumor changes than those with single lesion (15/28, 53.6%), including tumor volume reduction and anatomical shift (p < 0.001). PTV coverage of non-adaptive plans was below the prescribed coverage in 26/140 fractions (19%), with 12 (9%) failing by more than 10%. All 140 adaptive fractions met prescribed target coverage. The adaptive plans also had lower dose to whole brain than non-adaptive plans (p < 0.001).

Conclusions

Significant inter-fractional tumor changes could be found during FSRT in patients with BMs treated on the 1.5 T MR-Linac. Daily MR-guided re-optimization of treatment plans showed dosimetric benefit in patients with perilesional edema or multiple lesions.

Vestibular Schwannoma Hypofractionated Stereotactic Radiation Therapy in Five Fractions

AIM

To retrospectively analyse the long-term results of hypofractionated stereotactic radiation therapy (HSRT) applied in five fractions for vestibular schwannomas.

MATERIALS AND METHODS

One hundred and thirty-four patients with vestibular schwannomas underwent medical treatment of HSRT. The median follow-up time interval was 54 months (range 6-121 months). All patients had a prescribed dose of 22 Gy in five fractions to D90. Restaging was carried out by thin-slice contrast-enhanced T1 magnetic resonance imaging. Progression was defined as 2 mm post-treatment tumour enlargement. Progression or death for any reason was counted as an event in progression-free survival rates. Acute toxicity was defined as adverse events occurring within 3 months of HSRT; long-term toxicity was defined as such events occurring after 3 months.

RESULTS

In 74/128 patients who had >6 months of follow-up (54%), the HSRT resulted in a partial or a complete response. The mean time interval for response in 50% of these was 4 years, whereas in 49 patients (38%) vestibular schwannomas failed to show any response, resulting in stable disease. Five of 128 patients (4%) showed marked progressive vestibular schwannomas after treatment in the first 3 years; two of them received conventionally fractionated radiation therapy. Local control at 3, 5 and 7 years was 96%, 95% and 94%, respectively. Seven were lost to follow-up. The median planning target volume was 2.1 ml (range 0.78-8.66). The 3- and 5-year progression-free survival rates were 95% and 94%, respectively. Seven patients reported a marked deterioration in hearing ability. Post-radiation therapy magnetic resonance imaging showed variability in oedema collection, but no patient suffered from radio-necrosis. Grade 2 temporary facial nerve disorders were observed in 10 patients (8%) 3-6 months after HSRT.

CONCLUSION

Delivering HSRT in five fractions for vestibular schwannoma appears safe and efficient, combining both efficiency and short treatment time while optimising neurological function preservation.

Gamma Knife fractionated stereotactic radiotherapy (fSRT) of large brain tumors

The purpose of this study was to directly compare the plan quality of Gamma Knife (GK) (Elekta, Stockholm, Sweden)- vs linear accelerator (LINAC)-based delivery techniques for fractionated stereotactic radiotherapy (fSRT) of large brain metastases. Eighteen patients with clinical target volumes (CTVs) larger than 9.5 cc were selected to generate comparative plans for the prescription dose of 9 Gy × 3 fractions, utilizing the Eclipse (Varian, Palo Alto, US) vs Leksell GammaPlan (LGP) (Elekta, Stockholm, Sweden) treatment planning systems (TPS). Each GK plan was first developed using LGP's automatic planning, followed by manual adjustments/refinements. The same MRI and structures, including CTVs and organs at risk, were then DICOM-transferred to the Eclipse TPS. Volumetric Modulated Arc Therapy (VMAT) and Dynamic Conformal Arc (DCA) plans for a Truebeam, with high-definition multi-leaf collimators (MLCs), were developed on these MR images and structures using a single isocenter and 3 non-coplanar arcs. No planning target volume (PTV) margins were added, and no heterogeneity correction was used for either TPS. GK plans were prescribed to the 50% isodose line, and Eclipse VMAT and DCA plans allowed a maximum dose up to 170% and ∼125%, respectively. Gradient index (GI), Paddick Conformity Index (PCI), V_20GyRind, and V_4GyRind of all 3 techniques were calculated and compared. One-way analysis of variance (ANOVA) was performed to determine the statistical significance of the differences of these planning indices for the 3 planning techniques. A total of eighteen treatment targets were analyzed. Median CTV volume was 14.4 cc (range 9.5 cc - 55.9 cc). Mean ± standard deviation of PCI were 0.85 ± 0.03, 0.90 ± 0.03, and 0.72 ± 0.11 for GK, VMAT and DCA plans, respectively. They were respectively 2.64 ± 0.17, 2.46 ± 0.18, and 2.83 ± 0.48 for GI; 15.33 ± 8.45 cc, 10.47 ± 4.32 cc and 23.51 ± 16 cc for V_20GyRind; and 316.28 ± 138.35 cc, 317.81 ± 108.21 cc, and 394.85 ± 142.16 cc for V_4GyRind. The differences were statistically significant with p < 0.01 for all indices, except for V_4GyRind (p > 0.129). In conclusion, a direct dosimetric comparison using the same MRI scan and contours was performed to evaluate the plan quality of various fSRT delivery techniques for CTV > 9.5 cc. LINAC VMAT plans provided the best dosimetric outcome in regard to PCI, GI, and V_20GyRind. GK outcomes were similar to LINAC VMAT plans while LINAC DCA outcomes were significantly worse. Even though GK has a smaller physical penumbra, LINAC VMAT outperformed GK in this study due to enhanced penumbra sharpening and better beam optimization.

Effects of two different radiotherapies for craniopharyngiomas using stereotactic radiosurgery/ stereotactic radiotherapy or fractionated stereotactic radiotherapy

Background

Numerous studies have reported about good tumor control with both stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) for residual and recurrent craniopharyngiomas, but no studies have reported on the appropriate use of different types of radiation modalities. This study aimed to report the outcomes of SRS/stereotactic radiotherapy (SRT) or FSRT and compare tumor control in a single center.

Methods

From 2014 when TrueBeamTM STx with Novalis was introduced in our hospital to 2021, 21 patients underwent SRS/SRT or FSRT with gamma knife surgery (GKS) and Novalis. We have selected the radiation modalities considering mainly the distance of the optic nerve and chiasm. Imaging and clinical follow-up data were sent and reviewed.

Results

The mean age was 52 years and there were 11 men. Of the 21 total patients, three experienced SRS (GKS, 50% isodose 12-15 Gy), five underwent SRT (GKS or Novalis, 19.5-24 Gy 3 fractions), and 13 patients underwent FSRT (Novalis, 54 Gy 30 fractions). The median follow-up was 32.6 (range 17-44) months after SRS/SRT and 34.0 (range 4-61) months after FSRT. In the SRS/SRT group, the mean tumor volume decreased from 1.103 to 0.131 cm³ (P < 0.01), and in the FSRT group, from 3.015 to 1.012 cm³ (P < 0.01). No radiation-induced optic neuropathy and other acute toxicity occurred.

Conclusion

Craniopharyngioma can be expected to have very good tumor control by selecting SRS/SRT or FSRT depending on the distance between the optic nerve and the tumor.

Every other day stereotactic radiation therapy for the treatment of uveal melanoma decreases toxicity

BACKGROUND AND PURPOSE

To report the long-term results of stereotactic radiosurgery and fractionated stereotactic radiation therapy (SRS/FSRT) in patients with uveal melanoma (UM).

MATERIALS AND METHODS

We retrospectively evaluated the results of patients treated between 2007 and 2019. The primary endpoints were local control (LC), local recurrence-free survival (LRFS), enucleation-free survival (EFS) and treatment toxicity.

RESULTS

443 patients with 445 UMs were treated via CyberKnife®. According to the COMS classification, 70% of the tumors were small/medium and 30% were large. Median total RT dose was 54 Gy, median BED10 was 151 Gy. After a median 74-months follow-up, SRS/FSRT yielded an 83% overall LC rate. The 5- and 10-year LRFS rate was 74% and 56%, respectively. Patient age and the COMS size were prognostic for all survival endpoints. An increased SRS/FSRT dose was associated with higher LRFS and EFS rates. SRS/FSRT-related toxicity was observed in 49% of the eyes. Median visual acuity (VA) significantly deteriorated after SRS/FSRT in 76% of the treated eyes. The overall eye preservation rate was 62%, and the 5- and 10-year EFS rate was 64% and 36%, respectively. The delivery of FSRT every other day resulted in a significantly lower rate of toxicity and enucleation compared to FSRT on consecutive days.

CONCLUSION

A total dose of ≥45 Gy and BED_10Gy ≥ 112.5 SRS/FSRT is associated with a higher LC rate in patients with UM. Despite the favorable outcomes, treatment toxicity is the major limitation of this treatment. Toxicity and enucleation can be minimized by treating the eye every other day.

Interfractional change of tumor volume during fractionated stereotactic radiotherapy using gamma knife for brain metastases

PURPOSE

Fractionated stereotactic radiotherapy (FSRT) using gamma knife is useful for brain metastases. However, several uncertainties derived from fractionation pose issues for maintaining high-level accuracy. This study analyzed interfractional tumor change by performing radiological reassessment at the midterm of FSRT with ≥ 10 fractions, and the significance of replanning was evaluated.

METHODS

Data of FSRT using gamma knife with ≥ 10 fractions were retrospectively collected. Interfractional volume changes in MRI at the midterm of the irradiation period were analyzed. Radiological changes after FSRT and final outcomes were also investigated.

RESULTS

Overall, 114 lesions in 74 treatments from 66 patients were included, with previously irradiated lesions accounting for 46%. The median interval between planning and the interfractional MRI was 7 days. The interfractional change rates of tumor volume ranged from - 48 to + 72%. Significant interfractional enlargement was observed in 16 lesions (14%); evident regression was confirmed in 17 lesions (15%). Predictive factors for interfractional enlargement were small tumor and cystic lesion; high biologically effective dose was associated with regression. After FSRT, most lesions regressed within 6 months despite interfractional change type. The incidences of tumor control and radiation necrosis indicated no differences between interfractionally-regressed lesions and others.

CONCLUSION

This is the first study to evaluate interfractional tumor change in FSRT using gamma knife with ≥ 10 fractions, indicating significant volume changes in 29% of the lesions. These preliminary results suggest that interfractional reassessment of a treatment plan in FSRT with irradiation periods exceeding a week is necessary for more adaptive treatment.

Treatment for vestibular schwannoma: Systematic review and single arm meta-analysis

OBJECTIVE

Vestibular schwannoma is a benign tumor in the schwannoma cells of the 8th cranial nerve. It causes symptoms like tinnitus, vertigo and end up with loss of hearing so the appropriate treatment is very important. There are many treatment techniques including conservative, surgery and radiosurgery. We aimed to systematically review and single arm meta-analysis the different treatment techniques of vestibular schwannoma.

METHODS

A comprehensive literature search using thirteen databases including PubMed, Scopus, and Web of Science was performed. All clinical trials about treatment vestibular schwannoma were included and single arm meta-analyzed. We assessed the risk of bias using ROBIN-I's tool and scale of Council Australia's Cancer Guidelines Wiki. The protocol was registered in PROSPERO (CRD42018089784) and has been updated on 17 April 2019.

RESULTS

A total of 35 clinical trials studies were included in the final analysis. The pooled proportion of stable hearing capability in patients receiving gamma knife radiosurgery (GKRS) was 64% (95% CI: 52%-74%). GKRS favored increased hearing capability 10% (95% CI: 7%-16%). Regarding tumor size, GKRS is the most protective method 53% (95% CI: 37%-69%). Complications occurred most commonly in single fractional linac stereotactic radiosurgery (SFSRT) 37% (95% CI: 12%-72%).

CONCLUSION

Our analysis suggested gamma knife radiosurgery could be the most ideal treatment for vestibular schwannoma based on stabilizing hearing capability, increasing hearing capability, decreasing tumor size and complications.

Interfractional target changes in brain metastases during 13-fraction stereotactic radiotherapy

BACKGROUND

The risk for radiation necrosis is lower in fractionated stereotactic radiotherapy (SRT) than in conventional radiotherapy, and 13-fraction SRT is our method of choice for the treatment of brain metastases ≥ around 2 cm or patients who are expected to have a good prognosis. As 13-fraction SRT lasts for at least 17 days, adaptive radiotherapy based on contrast-enhanced mid-treatment magnetic resonance imaging (MRI) is often necessary for patients undergoing 13-fraction SRT. In this study, we retrospectively analyzed interfractional target changes in patients with brain metastases treated with 13-fraction SRT.

METHODS

Our analyses included data from 23 patients and 27 metastatic brain lesions treated with 13-fraction SRT with dynamic conformal arc therapy. The peripheral dose prescribed to the planning target volume (PTV) was 39-44.2 Gy in 13-fractions. The gross tumor volume (GTV) of the initial SRT plan (initial GTV), initial PTV, and modified GTV based on the mid-treatment MRI scan (mid-treatment GTV) were assessed.

RESULTS

The median initial GTV was 3.8 cm³ and the median time from SRT initiation to the mid-treatment MRI scan was 6 days. Compared to the initial GTV, the mid-treatment GTV increased by more than 20% in five lesions and decreased by more than 20% in five lesions. Interfractional GTV volume changes of more than 20% were not significantly associated with primary disease or the presence of cystic components/necrosis. The mid-treatment GTV did not overlap perfectly with the initial PTV in more than half of the lesions.

CONCLUSIONS

Compared to the initial GTV, the mid-treatment GTV changed by more than 20% in almost one-third of lesions treated with 13-fraction SRT. As SRT usually generates a steep dose gradient as well as increasing the maximum dose of PTV compared to conventional radiotherapy, assessment of the volume and locational target changes and adaptive radiotherapy should be considered as the number of fractions increases.

Stereotactic reirradiation with temozolomide in patients with recurrent aggressive pituitary tumors and pituitary carcinomas

OBJECTIVES

To evaluate the efficacy of a second course of fractionated stereotactic radiotherapy (re-SRT) and temozolomide (TMZ) as salvage treatment option in patients with aggressive pituitary tumors (APTs) and pituitary carcinomas (PCs).

PATIENTS AND METHODS

Twenty-one patients with recurrent or progressive APTs (n = 17) and PCs (n = 4) who received combined TMZ and re-SRT, 36 Gy/18fractions or 37.5 Gy/15fractions, were retrospectively evaluated. TMZ was given at a dose of 75 mg/m² given concurrently to re-SRT, and then 150-200 mg/m²/day for 5 days every 4 weeks or 50 mg/m² daily for 12 months. Local control (LC) and overall survival (OS) were calculated from the time of re-SRT by Kaplan-Meier method.

RESULTS

With a median follow-up of 27 months (range 12-58 months), 2-year and 4-year LC rates were 73% and 65%, respectively; 2-year and 4-year survival rates were 82% and 66%, respectively. A complete response was achieved in 2 and partial response in 11 patients. Six patients recurred with a median time to progression of 14 months. O(6)-Methylguanine-DNA methyltransferase (MGMT) status and tumor volume emerged as prognostic factors. Grade 3 radiation-related toxicities occurred in 3 (14%) patients. Grade 2 or 3 hematologic toxicities during chemotherapy occurred in 8 (38%) patients.

CONCLUSION

Re-SRT and TMZ is a safe treatment offering high LC in patients with progressive APTs and PCs. The potential advantages of combined chemoradiation as up-front or salvage treatment need to be explored in prospective trials.

Radiation techniques in aggressive pituitary tumours and carcinomas

Defining the role of radiation techniques in treatment of aggressive pituitary tumours and carcinomas is a difficult task: indeed, studies reported in the literature on this topic can probably be counted on the fingers of one hand. To try to better define these roles, it is thus necessary to extrapolate based on anti-secretory and anti-tumor efficacy reported in studies on non-selected pituitary tumours, regardless of their pathological status and intrinsic aggressiveness. Generally, radiation techniques are delivered as part of a multimodal treatment, usually with the primary aim of controlling tumor volume. Side-effects need to be divided into short and long-term, also depending on the overall prognosis of the tumour, since hypopituitarism will likely appear in the majority of patients, extra-pituitary side-effects, which have been reported after a significant delay after the procedure, can only be considered in patients with less aggressive pituitary tumours. In this review, we will first detail the different modalities of radiation techniques and the inherent limits of each technique depending on the volume and the localization of the tumour. We will then discuss the anti-tumour and anti-secretory efficacy of radiation techniques in aggressive pituitary tumors, either as a single treatment or as part of a multimodal treatment. Finally we will discuss the technique-specific side-effects.

Fractionated stereotactic radiotherapy as a therapeutic alternative

Intramuscular cavernous venous malformations affecting extraocular muscles are extremely uncommon. Due to their location, complete resection could be difficult. A clinical case is presented of an inferior rectus muscle orbital cavernous malformation treated with fractionated stereotactic radiotherapy after post-surgical excision recurrence. The malformation responded to radiotherapy with a reduction in size and symptoms. Fractionated stereotactic radiotherapy is an alternative and effective treatment for cavernous venous malformations that are surgically challenging due to their radiotherapy sensitivity.

Normofractionated stereotactic radiotherapy versus CyberKnife-based hypofractionation in skull base meningioma: a German and Italian pooled cohort analysis

Background

This retrospective German and Italian multicenter analysis aimed to compare the role of normofractionated stereotactic radiotherapy (nFSRT) to CyberKnife-based hypofractionated stereotactic radiotherapy (CK-hFSRT) for skull base meningiomas.

Methods

Overall, 341 patients across three centers were treated with either nFSRT or CK-hFSRT for skull base meningioma. Treatment planning was based on computed tomography (CT) and magnetic resonance imaging (MRI) following institutional guidelines. Most nFSRT patients received 33 × 1.8 Gy, and most CK-hFSRT patients received 5 × 5 Gy. The median follow-up time was 36 months (range: 1–232 months).

Results

In the CK-hFSRT group, the 1-, 3-, and 10-year local control (LC) rates were 99.4, 96.8, and 80.3%, respectively. In the nFSRT group, the 1-, 3-, and 10-year LC rates were 100, 99, and 79.1%, respectively. There were no significant differences in LC rates between the nFSRT and CK-hFSRT groups (p = 0.56, hazard ratio = 0.76, 95% confidence interval, 0.3–1.9). In the CK-hFSRT group, only one case (0.49%) of severe toxicity (CTCAE 4.0 ≥ 3) was observed. In the nFSRT group, three cases (2.1%) of grade III toxicity were observed.

Conclusion

This analysis of pooled data from three centers showed excellent LC and low side effect rates for patients treated with CK-hFSRT or nFSRT. The efficacy, safety, and convenience of a shortened treatment period provide a compelling case for the use of CK-hFSRT in patients with moderate size skull base meningioma and provided that OAR constraints are met.

Impact of adjuvant fractionated stereotactic radiotherapy dose on local control of brain metastases

PURPOSE

The aim of this study was to determine whether a higher biological effective dose (BED) would result in improved local control in patients treated with fractionated stereotactic radiotherapy (FSRT) for their resected brain metastases.

METHODS

Patients with newly diagnosed brain metastases without previous brain radiotherapy were retrospectively reviewed. Patients underwent surgical resection of at least one brain metastasis and were treated with adjuvant FSRT, delivering 25-36 Gy in 5-6 fractions. Outcomes were computed using Kaplan-Meier survival analysis and univariate analysis.

RESULTS

Fifty-four patients with 63 post-operative cavities were included. Median follow-up was 16 months (3-60). Median metastasis size at diagnosis was 2.9 cm (0.6-8.1) and median planning target volume was 19.7 cm³ (6.3-68.1). Two-year local control (LC) was 83%. When stratified by dose, 2 years LC rate was 95.1% in those treated with 30-36 Gy in 5-6 fractions (BED₁₀ of 48-57.6 Gy₁₀) versus 59.1% lesions treated with 25 Gy in 5 fractions (BED₁₀ of 37.5 Gy₁₀) (p < 0.001). LC was not associated with resection cavity size. One year overall survival was 68.7%, and was independent of BED₁₀. Symptomatic radiation necrosis occurred in 7.9% of patients and was not associated with dose.

CONCLUSION

In the post-operative setting, high-dose FSRT (BED₁₀ > 37.5 Gy₁₀) were associated with a significantly higher rate of LC compared to lower BED regimens. Overall, 25 Gy in 5 fractions is not an adequate dose to control microscopic disease. If selecting a 5-fraction regimen, 30 Gy in five fractions appears to provide excellent tumor bed control.

Adjuvant radiotherapy improves progression-free survival in intracranial atypical meningioma

Background

Meningiomas are the most common primary tumors of the central nervous system. In patients with WHO grade I meningiomas no adjuvant therapy is recommended after resection. In case of anaplastic meningiomas (WHO grade III), adjuvant fractionated radiotherapy is generally recommended, regardless of the extent of surgical resection. For atypical meningiomas (WHO grade II) optimal postoperative management has not been clearly defined yet.

Methods

We conducted a retrospective analysis of patients treated for intracranial atypical meningioma at Charité Universitätsmedizin Berlin from March 1999 to October 2018. Considering the individual circumstances (risk of recurrence, anatomical location, etc.), patients were either advised to follow a wait-and-see approach or to undergo adjuvant radiotherapy. Primary endpoint was progression-free survival (PFS).

Results

This analysis included 99 patients with atypical meningioma (WHO grade II). Nineteen patients received adjuvant RT after primary tumor resection (intervention group). The remaining 80 patients did not receive any further adjuvant therapy after surgical resection (control group). Median follow-up was 37 months. Median PFS after primary resection was significantly longer in the intervention group than in the control group (64 m vs. 37 m, p = 0.009, HR = 0.204, 95% CI = 0.062–0.668). The influence of adjuvant RT was confirmed in multivariable analysis (p = 0.041, HR = 0.192, 95% CI = 0.039–0.932).

Conclusions

Our study adds to the evidence that RT can improve PFS in patients with atypical meningioma.

Fractionated stereotactic radiotherapy for local control of resected brain metastases

PURPOSE

Postoperative stereotactic radiosurgery (SRS) has been shown to establish local control in patients with resected brain metastases, yet its efficacy may be limited, particularly for resected lesions with large post-operative resection cavities. We describe the efficacy of postoperative fractionated stereotactic radiotherapy (FSRT) for local control in patients who have undergone resection for brain metastases.

METHODS

In this retrospective cohort study, we analyzed patients who received FSRT for resected brain metastases in 3 or 5 fractions. Time to local recurrence was the primary endpoint in this study.

RESULTS

Sixty-seven patients (n = 29 female, n = 38 male) met study criteria for review. The median age of the cohort was 62 years (range 18-79 years). Median preoperative tumor volume was 11.1 cm³ (range 0.4-77.0 cm³). The rate of local control was 91.0% at 6 months, 85.1% at 12 months, and 85.1% at 18 months. Estimates of freedom from local recurrence at 6 and 12 months were 90.9% and 84.3%, respectively. Higher biologically equivalent doses (BED10) were found to be predictive of longer freedom from local recurrence on univariate and multivariable analysis. Larger cavity volumes were found to correspond to longer time to local recurrence on univariate and multivariable analysis.

CONCLUSION

Our results suggest that postoperative FSRT may be an effective method for providing local control to the surgical bed in patients with resected brain metastases, particularly for larger tumors not amenable to conventional, single-fraction SRS. Additional prospective studies are needed to confirm these findings.

Hearing Preservation for Vestibular Schwannomas Treated with Stereotactic Radiosurgery or Fractionated Stereotactic Radiotherapy

BACKGROUND

Vestibular schwannomas (VS) are benign intracranial neoplasms arising from the eighth cranial nerve for which targeted radiation therapy (RT) has proved increasingly successful. However, long-term hearing and related cranial nerve outcomes have been disputed for the 3 current RT modalities.

OBJECTIVE

To determine differences in hearing preservation for patients treated with stereotactic radiosurgery (SRS), fractionated stereotactic radiotherapy (FSRT), or hypofractionated stereotactic radiotherapy (hypoFSRT) for VS.

METHODS

A retrospective electronic chart review was conducted for all patients with unilateral VS treated with primary RT at a single academic medical center between 2000 and 2017. The primary outcome measure was preservation of serviceable hearing status in the affected ear at last follow-up. Secondary outcomes included tinnitus, vertigo, and imbalance.

RESULTS

A total of 33 FSRT cases, 21 SRS cases, and 6 hypoFSRT cases were identified. Postoperative deterioration in serviceable hearing and tinnitus showed significant differences across cohorts. The SRS cohort had a higher baseline incidence of nonserviceable hearing and disequilibrium compared with other cohorts before RT (P = 0.001 and 0.022, respectively); no differences in baseline morbidity were observed for vertigo and tinnitus. The 5-year tumor control rate was 95.2%, 93.9%, and 100% with SRS, FSRT, and hypoFSRT, respectively.

CONCLUSIONS

Our series indicated an excellent tumor control rate in all the modalities. Our SRS cohort showed increased incidence and shorter time to hearing deterioration compared with the FSRT and hypoFSRT cohorts. The FSRT and hypoFSRT cohorts have shown comparable overall outcomes. Onset of post-RT tinnitus was observed only with FSRT.

Progression of hearing loss after LINAC-based stereotactic radiotherapy for vestibular schwannoma is associated with cochlear dose, not with pre-treatment hearing level

Background

Although stereotactic radiotherapy (SRT) for vestibular schwannoma has demonstrated excellent local control rates, hearing deterioration is often reported after treatment. We therefore wished to assess the change in hearing loss after SRT and to determine which patient, tumor and treatment-related factors influence deterioration.

Methods

We retrospectively analyzed progression of hearing loss in patients with vestibular schwannoma who had received stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) as a primary treatment between 2000 and 2014. SRS had been delivered as a single fraction of 12 Gy, and patients treated with FSRT had received 30 fractions of 1.8 Gy. To compare the effects of SRS and FSRT, we converted cochlear doses into EQD₂. Primary outcomes were loss of functional hearing, Gardner Robertson (GR) classes I and II, and loss of baseline hearing class. These events were used in Kaplan Meier plots and Cox regression. We also calculated the rate of change in Pure Tone Average (PTA) in dB per month elapsed after radiation—a measure we use in linear regression—to assess the associations between the rate of change in PTA and age, pre-treatment hearing level, tumor size, dose scheme, cochlear dose, and time elapsed after treatment (time-to-first-audiogram).

Results

The median follow-up was 36 months for 67 SRS patients and 63 months for 27 FSRT patients. Multivariate Cox regression and in linear regression both showed that the cochlear V90 was significantly associated with the progression of hearing loss. But although pre-treatment PTA correlated with rate of change in Cox regression, it did not correlate in linear regression. The time-to-first-audiogram was also significantly associated, indicating time dependency of the rate of change. None of the analysis showed a significant difference between dose schemes.

Conclusions

We found no significant difference between SRS and FSRT. As the deterioration in hearing after radiotherapy for vestibular schwannoma was associated with the cochlea V90, restricting the V90 may reduce progression of hearing loss. The association between loss of functional hearing and baseline PTA seems to be biased by the use of a categorized variable for hearing loss.

Management of nonfunctioning pituitary tumors: radiotherapy

External beam radiotherapy (RT) is an essential part of the management of intracranial tumors and has been used in treating pituitary adenomas for more than five decades. It has been demonstrated that conventional RT for postoperative residual or progressive nonfunctioning pituitary adenomas (NFAs) present an excellent long-term local tumor control, although its use has been limited because of the potential late toxicity related to radiation treatments. Recent advances in radiation techniques have led to more accurate treatments, rendering obsolete many commonly held views of the "old" radiotherapy. New techniques include intensity modulated radiotherapy, volumetric-modulated arc therapy, and stereotactic techniques, either stereotactic radiosurgery or fractionated stereotactic radiotherapy. New techniques allow the delivering of higher radiation doses to the target with rapid dose fall-off in the surrounding normal tissues, and potentially limiting the long term toxicity of radiation. In this review, we present a critical analysis of the most recent available literature on the use of radiation in patients with NFAs, focusing particularly on the efficacy and safety of radiation stereotactic techniques.

Hippocampal sparing in stereotactic radiotherapy for brain metastases: To contour or not contour the hippocampus?

PURPOSE

The aim of our study was to evaluate hippocampal irradiation in patients treated with fractionated stereotactic brain radiotherapy.

PATIENTS AND METHODS

Retrospective hippocampal dosimetric analysis performed on 22 patients with one to four brain metastases treated with fractionated stereotactic radiotherapy using volumetric intensity-modulated arc therapy. Original plans did not include hippocampus as avoidance structure in optimization criteria; hippocampus was retrospectively delineated on magnetic resonance coregistered with planning CT and using as reference the RTOG 0933 atlas. Hippocampus was defined both as a single and as pair organ. Constraints analysed were: Dmax<16Gy, D40%<7.3Gy, D100%=Dmin<9Gy. Assuming a α/β ratio of 2Gy, biologically equivalent dose in 2Gy fractions was calculated. Hippocampal-sparing plans were developed in cases where hippocampal constraints were not respected in the original plan.

RESULTS

Among constraints analysed Dmax and D40% have been exceeded in ten out of 22 cases. The constraints were not respected in patients with more than one metastatic lesion and in three patients with only one lesion. Considering all exceeded constraints values in non-hippocampal sparing plans, the 50% of them was respected after replanning. No significant differences were found among conformity and homogeneity index between non-hippocampal sparing and hippocampal sparing plans.

CONCLUSION

Volumetric intensity-modulated arc therapy hippocampal sparing plans significantly decreases dose to hippocampus assuring an equal target coverage and organs at risk avoiding.

Stereotactic radiosurgery vs. fractionated radiotherapy for tumor control in vestibular schwannoma patients: a systematic review

Objective

Repeated controlled studies have revealed that stereotactic radiosurgery is better than microsurgery for patients with vestibular schwannoma (VS) <3 cm in need of intervention. In this systematic review we aimed to compare results from single-fraction stereotactic radiosurgery (SRS) to fractionated stereotactic radiotherapy (FSRT) for patients with VS.

Data sources and eligibility criteria

We systematically searched MEDLINE, Web of Science, Embase and Cochrane and screened relevant articles for references. Publications from 1995 through 2014 with a minimum of 50 adult (>18 years) patients with unilateral VS, followed for a median of >5 years, were eligible for inclusion. After screening titles and abstracts of the 1094 identified articles and systematically reviewing 98 of these articles, 19 were included.

Intervention

Patients with unilateral VS treated with radiosurgery were compared to patients treated with fractionated stereotactic radiotherapy.

Results

No randomized controlled trial (RCT) was identified. None of the identified controlled studies comparing SRS with FSRT were eligible according to the inclusion criteria. Nineteen case series on SRS (n = 17) and FSRT (n = 2) were included in the systematic review. Loss of tumor control necessitating a new VS-targeted intervention was found in an average of 5.0% of the patients treated with SRS and in 4.8% treated with FSRT. Mean deterioration ratio for patients with serviceable hearing before treatment was 49% for SRS and 45% for FSRT, respectively. The risk for facial nerve deterioration was 3.6% for SRS and 11.2% for FSRT and for trigeminal nerve deterioration 6.0% for SRS and 8.4% for FSRT. Since these results were obtained from case series, a regular meta-analysis was not attempted.

Conclusion

SRS and FSRT are both noninvasive treatment alternatives for patients with VS with low rates of treatment failure in need of rescue therapy. In this selection of patients, the progression-free survival rates were on the order of 92–100% for both treatment options. There is a lack of high-quality studies comparing radiation therapy alternatives for patients with VS. Finally, 19 articles reported long-term tumor control after SRS, while only 2 articles reported long-term FSRT results, making effect estimates more uncertain for FSRT.

Electronic supplementary material

The online version of this article (doi:10.1007/s00701-017-3164-6) contains supplementary material, which is available to authorized users.

Target delineation and optimal radiosurgical dose for pituitary tumors

Stereotactic radiosurgery (SRS) delivered as either single-fraction or multi-fraction SRS (2–5 fractions) is frequently employed in patients with residual or recurrent pituitary adenoma. The most common delivery systems used for SRS include the cobalt-60 system Gamma Knife, the CyberKnife (CK) robotic radiosurgery system, or a modified conventional radiotherapy machine (linear accelerator, LINAC). Tumor control and normalization of hormone hypersecretion have been reported in 75–100 % and 25–80 % of patients, respectively. Hypopituitarism is the most commonly reported late complication of radiation treatment, whereas other toxicities occur less frequently. We have provided an overview of the recent available literature on SRS in patients with a pituitary adenoma. Critical aspects of pituitary irradiation, including target delineation and doses to organs at risk, optimal radiation dose, as well as the long-term efficacy and toxicity of SRS for either nonfunctioning or secreting pituitary adenomas are discussed. Single-fraction SRS represents an effective treatment for patients with a pituitary adenoma; however, caution should be used for lesions > 2.5–3 cm in size and/or involving the anterior optic pathway. Future studies will be necessary to optimize target doses and critical organ dose constrains in order to reduce the long-term toxicity of treatments while maintaining high efficacy.

A Feasibility Study of a Tilted Head Position in Helical Tomotherapy for Fractionated Stereotactic Radiotherapy of Intracranial Malignancies

Herein, we evaluated the feasibility of placing patients in a tilted head position as part of routine clinical practice for fractionated stereotactic radiotherapy (FSRT) of intracranial tumors using helical tomotherapy (HT), by assessing its dosimetric benefit and setup accuracy. We reviewed treatment plans of four cases that were to receive FSRT for brain lesions in normal and head-tilted positions. These patients underwent two computed tomography (CT) scans: first in the normal supine position and then in the supine position with the head tilted at a 458 angle. Two separate HT plans for each position were generated in these four patients, using the same planning parameters. Plans were compared for target conformity and dose homogeneity. Maximum and average doses to critical organs, including normal brain, brain stem, optic chiasm, optic nerves, and the eyes, were considered. To evaluate setup accuracy, patient movement during treatment was assessed by post-treatment megavoltage CT scans. Both HT plans achieved similar conformal and homogeneous dose coverage to the target. Head-tilted HT delivered lower average and maximum doses to critical organs in the cases where the tumor was located on the same plane with critical organs, particularly when they were not directly attached. Placement in the head-tilted position without a mouthpiece allowed for increased patient movement during treatment, while use of a mouthpiece reduced patient movement to even less than that observed for normal setup in the supine position. This pilot study showed that placement in a tilted head position for FSRT of intracranial tumors using HT may be of clinical use, but depends on the tumor location.

Fractionated stereotactic radiotherapy of benign skull-base tumors: a dosimetric comparison of volumetric modulated arc therapy with Rapidarc® versus non-coplanar dynamic arcs

Background

Benign tumors of the skull base are a challenge when delivering radiotherapy. An appropriate choice of radiation technique may significantly improve the patient’s outcomes. Our study aimed to compare the dosimetric results of fractionated stereotactic radiotherapy between non-coplanar dynamic arcs and coplanar volumetric modulated arctherapy (Rapidarc®).

Methods

Thirteen patients treated with Novalis TX® were analysed: six vestibular schwannomas, four pituitary adenomas and three meningioma. Two treatment plans were created for each case: dynamic arcs (4–5 non coplanar arcs) and Rapidarc® (2 coplanar arcs). All tumors were >3 cm and accessible to both techniques. Patients had a stereotactic facemask (Brainlab) and were daily repositioned by Exactrac®. GTV and CTV were contoured according to tumor type. A 1-mm margin was added to the CTV to obtain PTV. Radiation doses were 52.2–54 Gy, using 1.8 Gy per fraction. Treatment time was faster with Rapidarc®.

Results

The mean PTV V95 % was 98.8 for Rapidarc® and 95.9 % for DA (p = 0.09). Homogeneity index was better with Rapidarc®: 0.06 vs. 0.09 (p = 0.01). Higher conformity index values were obtained with Rapidarc®: 75.2 vs. 67.9 % (p = 0.04). The volume of healthy brain that received a high dose (V90 %) was 0.7 % using Rapidarc® vs. 1.4 % with dynamic arcs (p = 0.05). Rapidarc® and dynamic arcs gave, respectively, a mean D40 % of 10.5 vs. 18.1 Gy (p = 0.005) for the hippocampus and a Dmean of 25.4 vs. 35.3 Gy (p = 0.008) for the ipsilateral cochlea. Low-dose delivery with Rapidarc® and dynamic arcs were, respectively, 184 vs. 166 cm³ for V20 Gy (p = 0.14) and 1265 vs. 1056 cm³ for V5 Gy (p = 0.67).

Conclusions

Fractionated stereotactic radiotherapy using Rapidarc® for large benign tumors of the skull base provided target volume coverage that was at least equal to that of dynamics arcs, with better conformity and homogeneity and faster treatment time. Rapidarc® also offered better sparing of the ipsilateral cochlea and hippocampus. Low-dose delivery were similar between both techniques.

Re-irradiation of recurrent anaplastic ependymoma using radiosurgery or fractionated stereotactic radiotherapy

PURPOSE

Recurrent ependymomas were retreated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT). The efficacy, toxicities, and differences between SRS and FSRT were analyzed.

METHODS

Eight patients with recurrent ependymomas fulfilling the criteria described below were evaluated. Inclusion criteria were: (1) the patient had previously undergone surgery and conventional radiotherapy as first-line treatment; (2) targets were located in or adjacent to the eloquent area or were deep-seated; and (3) the previously irradiated volume overlapped the target lesion.

RESULTS

FSRT was delivered to 18 lesions, SRS to 20 lesions. A median follow-up period was 23 months. The local control rate was 76 % at 3 years. No significant differences in local control were observed due to tumor size or fractionation schedule. Lesions receiving >25 Gy/5 fr or 21 Gy/3 fr did not recur within 1 year, whereas no dose-response relationship was observed in those treated with SRS. No grade ≥2 toxicity was observed.

CONCLUSION

Our treatment protocol provided an acceptable LC rate and minimal toxicities. Because local recurrence of tumors may result in patient death, a minimum dose of 21 Gy/3 fr or 25 Gy/5 fr or higher may be most suitable for treatment of these cases.

Long-term results of fractionated stereotactic radiotherapy as third-line treatment in acromegaly

The treatment of acromegaly is based on surgery, drugs, and radiotherapy as a third-line option. Fractionated stereotactic radiotherapy (FSRT) is a new technique with a need for long-term evaluation. The purpose of the study was to evaluate long-term results of FSRT in acromegaly. Overall, 34 patients [sex ratio 1.12, age 45 (5-65) years] with a pituitary adenoma of 24.5 (9-76) mm including 20 invasive tumors were treated by radiotherapy in fractionated stereotactic conditions delivering 50 gy in 27 sessions. Baseline growth hormone (GH) and IGF1 levels were 18 (±14.5) and 632.6 (±339) µg/L, respectively. Indications of FSRT were failure of surgery and drug treatments (n = 30) or contraindication/refusal of surgery (n = 4). Hormonal control was defined by normal age- and sex-adjusted IGF1. Remission was defined by hormonal control after withdrawal of drugs for a minimum of three consecutive months. Data were analyzed in SPSS software with a significance level at p < 0.05. After a mean follow-up of 152 months, hormonal control was achieved in 33 patients (97 %) with withdrawal of drugs in 13 patients (38.2 %) without any recurrence. Factors found to be significantly associated to remission in a multivariate Cox regression were lower baseline hormone levels (GH and IGF1) and smaller tumor size. Tumor control was achieved in all patients. Acquired hypopituitarism after radiotherapy was the main side effect reported with a rate of 39 %. FSRT seems to be an effective and well tolerated third-line treatment of acromegaly, particularly adapted to macro adenomas treatment.

Re-resection for recurrent high-grade glioma in the setting of re-irradiation: more is not always better

The optimal treatment for patients with recurrent high grade glioma (HGG) remains controversial. Available therapies include surgery, re-irradiation, alternating electric fields or systemic therapy. Here we investigate whether re-resection will improve survival in patients receiving repeat radiotherapy for tumor recurrence. 231 consecutive patients with recurrent HGG treated with re-irradiation between 1994 and 2012 were analyzed. 105 patients underwent re-resection. Re-irradiation was delivered using daily fractions of 3.5 Gy to a median total dose of 35 Gy. Survival was then analyzed comparing patients with and without re-resection. Overall survival (OS) and survival from the first recurrence are reported. Univariate and cox-proportional hazard modeling was performed in a step-wise multivariate analysis using known prognostic factors. The median follow-up time from initial diagnosis was 25.7 months. The median OS from initial diagnosis of the entire group was 22.5 months. There was no significant difference in median overall survival between patients who received re-resection versus no re-resection, 23 versus 21.9 months respectively (p = 0.6). Additionally, there was no difference in median survival from the time of first recurrence 10.5 months without re-resection versus 11.1 months with re-resection (p = 0.09). After adjusting for known prognostic variables, only age remained significant. Re-irradiation is an effective salvage therapy for patients with localized, progressive high grade glioma, achieving a median survival of 10-11 months from re-irradiation. Our data reveals no significant improvement in survival with the addition of re-resection to re-irradiated patients with HGG.

Fractionated stereotactic radiotherapy plus bevacizumab after response to bevacizumab plus irinotecan as a rescue treatment for high-grade gliomas

AIM

To evaluate the possibility of implementing a new scheme of rescue treatment after relapse or progression of high-grade glioma (HGG) treated at the first-line with bevacizumab and irinotecan (BVZ+CPT11), evaluating the response and toxicity of associating BVZ and fractionated stereotactic radiotherapy (BVZ+FSRT).

MATERIALS AND METHODS

We retrospectively analysed data from 59 patients with relapse of HGG. Nine patients with HGG relapse after treatment using the Stupp protocol that were treated with BVZ+CPT11 for progression between July 2007 and August 2012, after which the response was assessed according to the Revised Assessment in Neuro-Oncology (RANO) criteria. BVZ was administered at a dose of 10 mg/kg and FSRT up to a prescribed dose of 30 Gy, 500 cGy per fraction, three days a week. The median follow-up was 38 months.

RESULTS

The treatment was well-tolerated by all patients. The response after nuclear magnetic resonance imaging (MRI) at 3-6 months was progression in two patients, stable disease in four, and three patients had a partial response. The median overall survival (OS) from diagnosis until death or the last control was 36.8 months. The median progression-free survival (PFS) was 10.8 months. The results from tumour sub-group analysis indicated that the PFS was not statistically significant although it seemed that it was higher in grade-III. The OS was higher in grade-III gliomas.

CONCLUSIONS

The combination of BVZ+FSRT as a second-line HGG relapse rescue treatment is well-tolerated and seems to offer promising results. We believe that multi-centre prospective studies are needed to determine the long-term efficacy and toxicity of this therapeutic approach.

Non surgical treatment of vestibular schwannoma

INTRODUCTION AND OBJECTIVES

To evaluate the results of local control and complications in the treatment of vestibular schwannoma treated with radiation.

METHODS

A retrospective study of 194 patients diagnosed with vestibular schwannoma, treated consecutively with radiation (either stereotactic radiosurgery or fractionated radiotherapy) from 1997 to 2012. We analyze the local control of tumors, as well as secondary complications to treatment with radiation.

RESULTS

A total of 132 (68%) tumors 68% are grade I-II tumors of the Koos classification, 40 (19%) are grade III, and 22 (13%) are grade IV. The tumors associated with neurofibromatosis (NF2), are 3.6% (6 tumors in 4 patients). The tumor control for the overall serie is 97% at 5 years, with a median follow-up of 80.4 months. For large tumors the local control is 91% at 5 years. Free survival of chronic complications is 89% at 5 years. Additionally, 50 tumors were subjected to regular follow-up with MRI without treatment, and 28 (58%) did not experienced tumor growth.

CONCLUSIONS

Radiation and follow up with MRI, are an alternative to surgery in the treatment of vestibular schwannoma, with a low level of complications inside of multidisciplinary approach.

Stereotactic radiotherapy and radiosurgery for non-functioning and secreting pituitary adenomas

Radiotherapy (RT) is frequently employed in patients with residual or recurrent pituitary adenoma with excellent rates of tumor control and remission of hormonal hypersecretion. Advances in RT have improved with the use of stereotactic techniques either as fractionated stereotactic radiotherapy (FSRT) or stereotactic radiosurgery (SRS), all aiming to improve the dose distribution to the tumor while reducing the amount of normal brain receiving significant doses of radiation. We provide an overview of the recent published literature on the long-term efficacy and adverse effects of stereotactic irradiation in nonfunctioning and secreting pituitary adenomas. Both techniques are associated with excellent clinical outcomes; however, advantages and drawbacks of each of these techniques in terms of local control, hormonal excess normalization, and radiation-induced toxicity remain a matter of debate. In clinical practice, single-fraction SRS may represent a convenient approach to patients with small and medium-sized pituitary adenoma away at least 2 mm from the optic chiasm, whereas FSRT is preferred over SRS for lesions >2.5-3 cm in size and/or involving the anterior optic pathway.

Long-term efficacy of fractionated radiotherapy for benign meningiomas

PURPOSE

To assess long term efficacy of fractionated stereotactic radiotherapy (fSRT) in the treatment of benign intracranial meningiomas.

MATERIALS AND METHODS

Retrospective study of 222 patients with histologically confirmed (58%) and unverified presumed (42%) grade I intracranial meningioma treated with fSRT in a single institution to doses of 50-55Gy in 30-33 fractions.

RESULTS

At a median follow-up of 43months (range 3-144) the 5 and 10years local control (LC) were 93% and 86%. Patients with tumors involving the optic nerve (42 patients) and patients with cavernous sinus/parasellar region meningiomas (78 patients) had 5 and 10years LC of 100%. The 5 and 10years survival probabilities were 93% and 84%. On multivariate analysis gender and tumor site were independent predictors of LC. Worsening of pre-existing cranial nerve deficit occurred in 8 (3.5%) and onset of new deficit in 1 (0.5%) patient. Two patients with optic nerve sheath meningioma (1%) developed radiation retinopathy. There were no cases of radiation necrosis or second brain tumors.

CONCLUSION

fSRT achieves excellent medium and long term tumor control with minimal morbidity particularly in patients with benign meningiomas involving the parasellar region and the optic nerves and questions the role of other treatment modalities for tumors at these locations.

Fractionated stereotactic radiotherapy with static field conformal and non coplanar arcs for pediatric patients with craniopharyngioma: analysis of long term visual outcome and endocrine toxicity

We assessed the efficacy and the toxicity for pediatric craniopharyngioma patients of fractionated stereotactic radiotherapy (FSRT). Between May 2000 and May 2009, 9 patients (male to female ratio, 5:4) with craniopharyngiomas underwent FSRT (median dose, 54 Gy). Among the 9 patients, 6 received radiation therapy (RT) for recurrent tumors and 3 for residual disease as adjuvant therapy after incomplete surgery. Median tumor volume was 2.3 cm³ (range, 0.1-5.8). The median target coverage was 93.7% (range 79.3-99.8%). The median conformity index was 0.94 (range, 0.6-1.4). Dose to the hippocampal region was assessed for all patients.After a median follow-up of 62.5 months (range, 32-127)the treated volume decreased in size in four of eight patients (50%). One patient was lost to follow-up. Local control and survival rates at 3 years were 100% and there were no marginal relapses. One patient, with a chronic bilateral papillary oedema after surgery, visual defect deteriorated after FSRT to a complete hemianopsia. One male patient with normal pituitary function before FSRT presented with precocious puberty at the age of 7.4 years, 24 months after FSRT. Four patients (50%) were severely obese at their last visit. FSRT is a safe treatment option for craniopharyngioma after incomplete resection.

The treatment of a large acoustic tumor with fractionated stereotactic radiotherapy

The treatment of acoustic neuromas (AN) usually involves surgical excision or stereotactic radiosurgery. However, for large AN (mean diameter > 3 cm), stereotactic radiosurgery is rarely used, leaving patients with limited noninvasive treatment options. Recently, the use of fractionated stereotactic radiotherapy (FSRT) has been effective in treating small to medium-sized AN. We present a patient with a large AN treated with FSRT. The patient was a 43-year-old man presenting with imbalance, tinnitus, vertigo, and right-sided hearing decline associated with vomiting and hydrocephalus. Magnetic resonance (MR) imaging revealed a large, 3.8-cm, right cerebellopontine-angle tumor compressing the fourth ventricle. Following right frontal ventriculoperitoneal shunt placement, the patient underwent FSRT for treatment of the tumor. Using the Radionics X-Knife 4.0 3D treatment planning system, a total of 54 Gy was delivered in 1.8-Gy daily fractions with the prescription isodose line of 90%. Treatments were delivered using a dedicated Varian 6/100 linear accelerator, and head immobilization was achieved with the Gill-Thomas-Cosman relocatable stereotactic frame. The patient was subsequently evaluated with serial contrast-enhanced MR imaging. Following FSRT, local control (defined as the absence of tumor progression) was achieved, and treatment was well tolerated. There was no hearing-related, trigeminal, or facial-nerve morbidity following FSRT at 63-month follow-up. Treating a patient with a large AN with FSRT resulted in local tumor control, with no trigeminal nerve, facial nerve, or hearing-related morbidity. These results support FSRT as a potential noninvasive treatment modality for AN some would consider too large for single-fraction stereotactic radiosurgery (SRS).