Re-irradiation after gross total resection of recurrent glioblastoma : Spatial pattern of recurrence and a review of the literature as a basis for target volume definition

Preferred Imaging for Target Volume Delineation for Radiotherapy of Recurrent Glioblastoma: A Literature Review of the Available Evidence

BACKGROUND

Recurrence in glioblastoma lacks a standardized treatment, prompting an exploration of re-irradiation's efficacy.

METHODS

A comprehensive systematic review from January 2005 to May 2023 assessed the role of MRI sequences in recurrent glioblastoma re-irradiation. The search criteria, employing MeSH terms, targeted English-language, peer-reviewed articles. The inclusion criteria comprised both retrospective and prospective studies, excluding certain types and populations for specificity. The PICO methodology guided data extraction, and the statistical analysis employed Chi-squared tests via MedCalc v22.009.

RESULTS

Out of the 355 identified studies, 81 met the criteria, involving 3280 patients across 65 retrospective and 16 prospective studies. The key findings indicate diverse treatment modalities, with linac-based photons predominating. The median age at re-irradiation was 54 years, and the median time interval between radiation courses was 15.5 months. Contrast-enhanced T1-weighted sequences were favored for target delineation, with PET-imaging used in fewer studies. Re-irradiation was generally well tolerated (median G3 adverse events: 3.5%). The clinical outcomes varied, with a median 1-year local control rate of 61% and a median overall survival of 11 months. No significant differences were noted in the G3 toxicity and clinical outcomes based on the MRI sequence preference or PET-based delineation.

CONCLUSIONS

In the setting of recurrent glioblastoma, contrast-enhanced T1-weighted sequences were preferred for target delineation, allowing clinicians to deliver a safe and effective therapeutic option; amino acid PET imaging may represent a useful device to discriminate radionecrosis from recurrent disease. Future investigations, including the ongoing GLIAA, NOA-10, ARO 2013/1 trial, will aim to refine approaches and standardize methodologies for improved outcomes in recurrent glioblastoma re-irradiation.

Adjuvant re-irradiation vs. no early re-irradiation of resected recurrent glioblastoma: pooled comparative cohort analysis from two tertiary centers

BACKGROUND

The optimal management strategy for recurrent glioblastoma (rGBM) remains uncertain, and the impact of re-irradiation (Re-RT) on overall survival (OS) is still a matter of debate. This study included patients who achieved gross total resection (GTR) after a second surgery after recurrence, following the GlioCave criteria.

METHODS

Inclusion criteria include being 18 years or older, having histologically confirmed locally recurrent IDHwt or IDH unknown GBM, achieving MRI-proven GTR after the second surgery, having a Karnofsky performance status of at least 60% after the second surgery, having a minimum interval of 6 months between the first radiotherapy and the second surgery, and a maximum of 8 weeks from second surgery to the start of Re-RT.

RESULTS

A total of 44 patients have met the inclusion criteria. The median OS after the second surgery was 14 months. All patients underwent standard treatment after initial diagnosis, including maximum safe resection, adjuvant radiochemotherapy and adjuvant chemotherapy. Re-RT did not significantly impact OS. However, MGMT promoter methylation status and a longer interval (> 12 months) between treatments were associated with better OS. Multivariate analysis revealed the MGMT status as the only significant predictor of OS.

CONCLUSION

Factors such as MGMT promoter methylation status and treatment interval play crucial roles in determining patient outcomes after second surgery. Personalized treatment strategies should consider these factors to optimize the management of rGBM. Prospective research is needed to define the value of re-RT after second surgery and to inform decision making in this situation.

Hypofractionated stereotactic re-irradiation for progressive glioblastoma: twelve years' experience of a single center

PURPOSE

We aimed to evaluate the prognostic factors and the role of stereotactic radiotherapy (SRT) as a re-irradiation technique in the management of progressive glioblastoma.

METHODS

The records of 77 previously irradiated glioblastoma patients who progressed and received second course hypofractionated SRT (1-5 fractions) between 2009 and 2022 in our department were evaluated retrospectively. Statistical Package for the Social Sciences (SPSS) version 23.0 (IBM, Armonk, NY, USA) was utilized for all statistical analyses.

RESULTS

The median time to progression from the end of initial radiotherapy was 14 months (range, 6-68 months). The most common SRT schedule was 30 Gy (range, 18-50 Gy) in 5 fractions (range, 1-5 fractions). The median follow-up after SRT was 9 months (range, 3-80 months). One-year overall (OS) and progression-free survival (PFS) rates after SRT were 46% and 35%, respectively. Re-irradiation dose and the presence of pseudoprogression were both significant independent positive prognostic factors for both OS (p = 0.009 and p = 0.04, respectively) and PFS (p = 0.008 and p = 0.04, respectively). For PFS, progression-free interval > 14 months was also a prognostic factor (p = 0.04). The treatment was well tolerated without significant acute toxicity. During follow-up, radiation necrosis was observed in 17 patients (22%), and 14 (82%) of them were asymptomatic.

CONCLUSION

Hypofractionated SRT is an effective treatment approach for patients with progressive glioblastoma. Younger patients who progressed later than 14 months, received higher SRT doses, and experienced pseudoprogression following SRT had improved survival rates.

Recurrent Glioblastoma: A Review of the Treatment Options

Glioblastoma is a disease with a poor prognosis. Multiple efforts have been made to improve the long-term outcome, but the 5-year survival rate is still 5-10%. Recurrence of the disease is the usual way of progression. In this situation, there is no standard treatment. Different treatment options can be considered. Among them would be reoperation or reirradiation. There are different studies that have assessed the impact on survival and the selection of patients who may benefit most from these strategies. Chemotherapy treatments have also been considered in several studies, mainly with alkylating agents, with data mostly from phase II studies. On the other hand, multiple studies have been carried out with target-directed treatments. Bevacizumab, a monoclonal antibody with anti-angiogenic activity, has demonstrated activity in several studies, and the FDA has approved it for this indication. Several other TKI drugs have been evaluated in this setting, but no clear benefit has been demonstrated. Immunotherapy treatments have been shown to be effective in other types of tumors, and several studies have evaluated their efficacy in this disease, both immune checkpoint inhibitors, oncolytic viruses, and vaccines. This paper reviews data from different studies that have evaluated the efficacy of different forms of relapsed glioblastoma.

Safety and patterns of survivorship in recurrent GBM following resection and surgically targeted radiation therapy: Results from a prospective trial

BACKGROUND

Treatment of recurrent glioblastoma (GBM) remains problematic with survival after additional therapy typically less than 12 months. We prospectively evaluated whether outcomes might be improved with resection plus permanent implantation of a novel radiation device utilizing the gamma-emitting isotope Cs-131 embedded within bioresorbable collagen tiles.

METHODS

Recurrent histologic GBM were treated in a single-arm trial. Following radiation, the surgical bed was lined with the tiles. Subsequent treatments were at the treating physician's discretion.

RESULTS

28 patients were treated (20 at first recurrence, range 1-3). Median age was 58 years, KPS was 80, female:male ratio was 10:18. Methylguanine methyltransferase (MGMT) was methylated in 11%, unmethylated in 18%, and unknown in 71%. Post implant, 17 patients (61%) received ≥1 course of systemic therapy. For all patients, Kaplan-Meier estimates of median time to local failure were 12.1 months, post-implant survival was 10.7 months for all patients and 15.1 months for patients who received systemic therapy; for all patients, median overall survival from diagnosis was 25.0 months (range 9.1-143.1). Sex, age, and number of prior progressions were not statistically significant. Local control was continuously maintained in 46% of patients. Two deaths within 30 days occurred, one from intracranial hemorrhage and one after persistent coma. Three symptomatic adverse events occurred: one wound infection requiring surgery and two late radiation brain injury, resolved non-surgically.

CONCLUSION

This pre-commercial trial demonstrated acceptable safety and favorable post-treatment local control and survival. The device has received FDA clearance for use in newly diagnosed malignant and all recurrent intracranial neoplasms.

Bevacizumab combined with re-irradiation in recurrent glioblastoma

Background

Glioblastoma is characterized by rich vasculature and abnormal vascular structure and function. Currently, there is no standard treatment for recurrent glioblastoma (rGBM). Bevacizumab (BEV) has established role of inhibiting neovascularization, alleviating hypoxia in the tumor area and activating the immune microenvironment. BEV may exert synergistic effects with re-irradiation (re-RT) to improve the tumor microenvironment for rGBM.

Purpose

The purpose of this study was to evaluate the safety, tolerability, and efficacy of a combination of BEV and re-RT for rGBM treatment.

Methods

In this retrospective study, a total of 26 rGBM patients with surgical pathologically confirmed glioblastoma and at least one event of recurrence were enrolled. All patients were treated with re-RT in combination with BEV. BEV was administered until progression or serious adverse events.

Results

Median follow-up was 21.9 months for all patients, whereas median progression-free survival (PFS) was 8.0 months (95% confidence interval [CI]: 6.5–9.5 months). In addition, the 6-month and 1-year PFS rates were 65.4% and 28.2%, respectively. The median overall survival (OS), 6-month OS rate, and 1-year OS rate were 13.6 months (95% CI: 10.2–17.0 months), 92.3%, and 67.5%, respectively. The patient showed good tolerance during the treatment with no grade > 3 grade side event and radiation necrosis occurrence rate of 0%. Combined treatment of gross total resection (GTR) before re-RT and concurrent temozolomide during re-RT was an independent prognostic factor that affected both OS and PFS in the whole cohort (OS: 0.067, 95% CI: 0.009–0.521, p = 0.010; PFS: 0.238, 95% CI: 0.076–0.744, p = 0.038).

Conclusion

In this study, re-RT combined with concurrent and maintenance BEV treatment was safe, tolerable, and effective in rGBM patients. Moreover, GTR before re-RT and selective concurrent temozolomide could further improve patient PFS and OS.

Reirradiation: A complex situation

Reirradiation of a tumor recurrence or second cancer in a previously irradiated area is challenging due to lack of high-quality physical, radiobiological, clinical data and inherent substantial risks of toxicity with cumulative dose and uncertain tissue recovery. Yet, major advances have been made in radiotherapy techniques, that have the potential to achieve cure while limiting severe toxicity rates, but still much research is necessary to better appraise the therapeutic index in such a complex situation.

Recurrent Glioblastoma Treatment: State of the Art and Future Perspectives in the Precision Medicine Era

Current treatment guidelines for the management of recurrent glioblastoma (rGBM) are far from definitive, and the prognosis remains dismal. Despite recent advancements in the pharmacological and surgical fields, numerous doubts persist concerning the optimal strategy that clinicians should adopt for patients who fail the first lines of treatment and present signs of progressive disease. With most recurrences being located within the margins of the previously resected lesion, a comprehensive molecular and genetic profiling of rGBM revealed substantial differences compared with newly diagnosed disease. In the present comprehensive review, we sought to examine the current treatment guidelines and the new perspectives that polarize the field of neuro-oncology, strictly focusing on progressive disease. For this purpose, updated PRISMA guidelines were followed to search for pivotal studies and clinical trials published in the last five years. A total of 125 articles discussing locoregional management, radiotherapy, chemotherapy, and immunotherapy strategies were included in our analysis, and salient findings were critically summarized. In addition, an in-depth description of the molecular profile of rGBM and its distinctive characteristics is provided. Finally, we integrate the above-mentioned evidence with the current guidelines published by international societies, including AANS/CNS, EANO, AIOM, and NCCN.

Congress of Neurological Surgeons systematic review and evidence-based guidelines update on the role of radiation therapy in the management of progressive and recurrent glioblastoma in adults

TARGET POPULATION

These recommendations apply to adult patients (18 years of age and above) with progressive/recurrent glioblastoma multiforme (pGBM) after first line combined multimodality treatment.

QUESTION

Can re-irradiation (by using conventional radiotherapy, fractionated radiosurgery, or single fraction radiosurgery) be used in patients with pGBM after the first adjuvant combined multimodality treatment with radiation and chemotherapy?

RECOMMENDATION

Level III: When the target tumor is amenable for additional radiation, re-irradiation is recommended as it provides improved local tumor control, as measured by best imaging response. Such re-irradiation can take the form of conventional fractionation radiotherapy, fractionated radiosurgery, or single fraction radiosurgery.

LEVEL III

Re-Irradiation is recommended in order to maintain or improve a patient's neurological status and quality of life prior to any further tumor progression.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Management of Progressive Glioblastoma in Adults: Update of the 2014 Guidelines

BACKGROUND

The Institute of Medicine best practice recommendation to review guidelines every 5 years is followed by the Congress of Neurological Surgeons Guidelines Committee. The aim of this work was to provide an updated literature review and evidence-based recommendations on the topic of diagnosis and treatment of patients with progressive glioblastoma (pGBM).

OBJECTIVE

To review the literature published since the last guidelines on pGBM dated 2014, with literature search ending in June 2012.

METHODS

PubMed, Embase, and Cochrane were searched for the period July 1, 2012, to March 31, 2019, using search terms and search strategies to identify pertinent abstracts. These were then screened using published exclusion/inclusion criteria to identify full-text review articles. Evidence tables were constructed using data derived from full-text reviews and recommendations made from the evidence derived.

RESULTS

From the total 8786 abstracts identified by the search, 237 full-text articles met inclusion/exclusion criteria and were included in this update. Two new level II recommendations derived from this work. For the diagnosis of patients with GBM, the use of diffusion-weighted images is recommended to be included in the magnetic resonance images with and without contrast used for surveillance to detect pGBM. For the treatment of patients with pGBM, repeat cytoreductive surgery is recommended to improve overall survival. An additional 21 level III recommendations were provided.

CONCLUSION

Recent published literature provides new recommendations for the diagnosis and treatment of pGBM. The Central Nervous System Guidelines Committee will continue to pursue timely updates to further improve the care of patients with diagnosis.https://www.cns.org/guidelines/browse-guidelines-detail/guidelines-management-of-progressive-glioblastoma.

Comparison of carbon ion and photon reirradiation for recurrent glioblastoma

PURPOSE

Purpose of this study was to investigate overall survival in recurrent glioblastoma treated with either carbon ion reirradiation or photon reirradiation.

MATERIALS AND METHODS

In this retrospective study we evaluated 78 consecutive patients with recurrent IDH (Isocitrate dehydrogenase)-wildtype glioblastoma (38 patients carbon ion re-radiotherapy, 40 patients photon re-radiotherapy) treated with either carbon ion reirradiation or stereotactic photon reirradiation. 45 Gy (RBE; 15 fractions) carbon ion reirradiation (CIRT) or 39 Gy (13 fractions) photon reirradiation (FSRT) was administered, respectively. Overall survival was investigated with respect to histological, clinical, and epidemiological features. Kaplan-Meier and multivariate Cox statistics were calculated. A propensity score-matched analysis of the FSRT and CIRT groups using variables from a validated prognosis score was carried out.

RESULTS

The type of reirradiation (CIRT vs. FSRT) significantly influenced overall survival-8.0 months vs. 6.5 months (univariate: p = 0.046)-and remained an independent prognostic factor in multivariate analysis (p = 0.017). Propensity score-adjusted analysis with CIRT versus FSRT as the dependent variable yielded a significant overall survival advantage for the CIRT group (median OS 8.9 versus 7.2 months, p = 0.041, 1‑year survival 29 versus 10%). Adverse events (AE) were evaluated for both subgroups. For the FSRT group no toxicity ≥ grade 4 occurred. For the CIRT subgroup no grade 5 AE occurred, but 1 patient developed a grade 4 radionecrosis. We encountered 4 grade 3 toxicities. One patient developed a zoster at the trunk, 2 progressed in their paresis, and 1 featured progressive dysesthesia.

CONCLUSION

In conclusion, carbon ion treatment is a safe and feasible treatment option for recurrent glioblastoma. Due to the retrospective nature of the study and two different dose levels for CIRT or FSRT, the improved outcome in CIRT reirradiation might be an effect of higher biological impact from carbon ions or a simple dose-escalation effect. This hypothesis needs prospective testing in larger patient cohorts. A prospective phase III randomized trial is in preparation at our center.

Re-irradiation for high-grade gliomas: Has anything changed?

Optimal management after recurrence or progression of high-grade gliomas is still undefined and remains a challenge for neuro-oncology multidisciplinary teams. Improved radiation therapy techniques, new imaging methods, published experience, and a better radiobiological knowledge of brain tissue have positioned re-irradiation (re-RT) as an option for many of these patients. Decisions must be individualized, taking into account the pattern of relapse, previous treatment, and functional status, as well as the patient’s preferences and expected quality of life. Many questions remain unanswered with respect to re-RT: Who is the most appropriate candidate, which dose and fractionation are most effective, how to define the target volume, which imaging technique is best for planning, and what is the optimal timing? This review will focus on describing the most relevant studies that include re-RT as salvage therapy, with the aim of simplifying decision-making and designing the best available therapeutic strategy.

Local treatment for relapsing glioblastoma: A decision-making tree for choosing between reirradiation and second surgery

In case of circumscribed recurrent glioblastoma (rec-GBM), a second surgery (Re-S) and reirradiation (Re-RT) are local strategies to consider. The aim is to provide an algorithm to use in the daily clinical practice. The first step is to consider the life expectancy in order to establish whether the patient should be a candidate for active treatment. In case of a relatively good life expectancy (>3 months) and a confirmed circumscribed disease(i.e. without multiple lesions that are in different lobes/hemispheres), the next step is the assessment of the prognostic factors for local treatments. Based on the existing prognostic score systems, patients who should be excluded from local treatments may be identified; based on the validated prognostic factors, one or the other local treatment may be preferred. The last point is the estimation of expected toxicity, considering patient-related, tumor-related and treatment-related factors impacting on side effects. Lastly, patients with very good prognostic factors may be considered for receiving a combined treatment.

Prospective Longitudinal Assessment of Quality of Life and Activities of Daily Living as Patient-Reported Outcome Measures in Recurrent/Progressive Glioma Treated with High-dose Salvage Re-irradiation

AIMS

To evaluate quality of life (QOL) and activities of daily living (ADL) longitudinally in patients treated with salvage re-irradiation for recurrent/progressive glioma. Secondary end points included post-re-irradiation survival.

MATERIALS AND METHODS

Patients with diffuse glioma, aged 18-70 years with preserved performance status and unequivocal evidence of recurrence/progression with a minimum 2-year time interval from index radiation therapy were eligible. QOL was assessed by the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core-30 (QLQ-C30) and brain cancer module (BN20). ADL was assessed using a modified Barthel's index. Assessments were carried out longitudinally, first before re-irradiation, at completion of re-irradiation and subsequently periodically on follow-up. Summary scores were calculated from raw scores as per the EORTC scoring manual; higher functional scores and lower symptom scores indicating better QOL. Summary mean scores for the modified Barthel's index were also calculated, with lower scores indicating higher disability. Differences between the summary scores at different time points were tested using the Friedman test.

RESULTS

In total, 225 assessments were carried out in 60 patients accrued on the study. A significant improvement in scores was noted for physical function (P < 0.001), emotional function (P = 0.002), cognitive function (P = 0.009) and social functioning (P = 0.047) over time. Role function scores (P = 0.182) and global health status scores (P = 0.074) remained stable. Among symptom scores, fatigue showed a statistically significant improvement over time (P = 0.01), whereas other symptom scores remained largely stable. There was a significant increase in the modified Barthel's index score over time (P = 0.001), suggesting greater functional independence. At a median follow-up of 12.9 months, the 1-year Kaplan-Meier estimates with 95% confidence intervals of post-re-irradiation progression-free survival and overall survival were 45.1% (31.5-58.7%) and 62.2% (49.2-75.2%), respectively.

CONCLUSIONS

High-dose salvage re-irradiation in carefully selected patients with recurrent/progressive glioma is associated with stable QOL (preserved functional domains and reduced symptom burden) and improvement in ADL (greater functional independence) over time with encouraging survival outcomes.

Low Fraction Size Re-irradiation for Large Volume Recurrence of Glial Tumours

The aim of the present study was to evaluate the efficacy of re-irradiation (re-RT) in patients with advanced local relapses of glial tumours and to define the factors influencing the result of the hyper-fractionated external beam therapy on progression after primary management. We have analysed the data of 55 patients with brain tumours (GBM: 28) on progression, who were re-irradiated between January 2007 and December 2018. The mean volume of the recurrent tumour was 118 cm³, and the mean planning target volume (PTV) was 316 cm³, to which 32 Gy was delivered in 20 fractions at least 7.7 months after the first radiotherapy, using 3D conformal radiotherapy (CRT) or intensity modulated radiotherapy (IMRT). The median overall survival (mOS) from the re-RT was 8.4 months, and the 6-month and the 12-month OS rate was 64% and 31%, respectively. The most important factors by univariate analysis, which significantly improved the outcome of re-RT were the longer time interval between the diagnosis and second radiotherapy (p = 0.029), the lower histology grade (p = 0.034), volume of the recurrent tumour (p = 0.006) and Karnofsky performance status (KPS) (p = 0.009) at the re-irradiation. Our low fraction size re-irradiation ≥ 8 months after the first radiotherapy proved to be safe and beneficial for patients with large volume recurrent glial tumours.

Radiomics in radiation oncology-basics, methods, and limitations

Over the past years, the quantity and complexity of imaging data available for the clinical management of patients with solid tumors has increased substantially. Without the support of methods from the field of artificial intelligence (AI) and machine learning, a complete evaluation of the available image information is hardly feasible in clinical routine. Especially in radiotherapy planning, manual detection and segmentation of lesions is laborious, time consuming, and shows significant variability among observers. Here, AI already offers techniques to support radiation oncologists, whereby ultimately, the productivity and the quality are increased, potentially leading to an improved patient outcome. Besides detection and segmentation of lesions, AI allows the extraction of a vast number of quantitative imaging features from structural or functional imaging data that are typically not accessible by means of human perception. These features can be used alone or in combination with other clinical parameters to generate mathematical models that allow, for example, prediction of the response to radiotherapy. Within the large field of AI, radiomics is the subdiscipline that deals with the extraction of quantitative image features as well as the generation of predictive or prognostic mathematical models. This review gives an overview of the basics, methods, and limitations of radiomics, with a focus on patients with brain tumors treated by radiation therapy.

Spatial distribution of malignant transformation in patients with low-grade glioma

Background

Malignant transformation represents the natural evolution of diffuse low-grade gliomas (LGG). This is a catastrophic event, causing neurocognitive symptoms, intensified treatment and premature death. However, little is known concerning the spatial distribution of malignant transformation in patients with LGG.

Materials and methods

Patients histopathological diagnosed with LGG and subsequent radiological malignant transformation were identified from two different institutions. We evaluated the spatial distribution of malignant transformation with (1) visual inspection and (2) segmentations of longitudinal tumor volumes. In (1) a radiological transformation site < 2 cm from the tumor on preceding MRI was defined local transformation. In (2) overlap with pretreatment volume after importation into a common space was defined as local transformation. With a centroid model we explored if there were particular patterns of transformations within relevant subgroups.

Results

We included 43 patients in the clinical evaluation, and 36 patients had MRIs scans available for longitudinal segmentations. Prior to malignant transformation, residual radiological tumor volumes were > 10 ml in 93% of patients. The transformation site was considered local in 91% of patients by clinical assessment. Patients treated with radiotherapy prior to transformation had somewhat lower rate of local transformations (83%). Based upon the segmentations, the transformation was local in 92%. We did not observe any particular pattern of transformations in examined molecular subgroups.

Conclusion

Malignant transformation occurs locally and within the T2w hyperintensities in most patients. Although LGG is an infiltrating disease, this data conceptually strengthens the role of loco-regional treatments in patients with LGG.

Margin reduction in radiotherapy for glioblastoma through 18F-fluoroethyltyrosine PET? - A recurrence pattern analysis

BACKGROUND AND PURPOSE

¹⁸F-fluoroethyltyrosine (¹⁸F-FET) PET is increasingly used in radiation treatment planning for the primary treatment of glioblastoma (GBM) patients additionally to contrast-enhanced MRI. To answer the question, whether a margin reduction in the primary treatment setting could be achieved through ¹⁸F-FET PET imaging, a recurrence pattern analysis was performed.

PATIENTS AND METHODS

GBM patients undergoing ¹⁸F-FET PET examination before primary radiochemotherapy from 05/2009 to 11/2014 were included into the recurrence pattern analysis. Biological tumour volumes were semi-automatically created and fused with MR-based gross tumour volumes (_MRGTVs). The pattern of recurrence was examined for _MRGTVs and for _PET-MRGTVs. The minimal margin including all recurrent tumour sites was assessed by gradual expansion of the _PET-MRGTVs and _MRGTVs until inclusion of all contrast-enhancing areas at recurrence.

RESULTS

36 GBM patients were included to the analysis. The minimal margin including all contrast enhancing tumour at recurrence was significantly smaller for the _PET-MRGTVs compared to the _MRGTVs (median 12.5 mm vs. 16.5 mm; p < 0.001, Wilcoxon-Test). _PET-MRGTVs with 15 mm CTV margins were significantly smaller than _MRGTVs with 20 mm CTV margins (median volume 255.92 vs. 258.35 cm³; p = 0.020, Wilcoxon-Test; excluding 3 cases with large non-contrast enhancing tumours). The pattern of recurrence of _PET-MRGTVs with 15 mm CTV margins was comparable to _MRGTVs with 20 mm CTV margins (32 vs. 30 central, 2 vs. 4 in-field, 2 vs. 2 ex-field and no marginal recurrences).

CONCLUSION

Target volume delineation of GBM patients can be improved through ¹⁸F-FET PET imaging prior to primary radiation treatment, since vital tumour can be detected more accurately. Furthermore, the results suggest that CTV margins could be reduced through ¹⁸F-FET PET imaging prior to primary RT of GBM.

On PTV definition for glioblastoma based on fiber tracking of diffusion tensor imaging data

Radiotherapy (RT) is commonly applied for the treatment of glioblastoma multiforme (GBM). Following the planning target volume (PTV) definition procedure standardized in guidelines, a 20% risk of missing non-local recurrences is present. Purpose of this study was to evaluate whether diffusion tensor imaging (DTI)-based fiber tracking may be beneficial for PTV definition taking into account the prediction of distant recurrences. 56 GBM patients were examined with magnetic resonance imaging (MRI) including DTI performed before RT after resection of the primary tumor. Follow-up MRIs were acquired in three month intervals. For the seven patients with a distant recurrence, fiber tracking was performed with three algorithms and it was evaluated whether connections existed from the primary tumor region to the distant recurrence. It depended strongly on the used tracking algorithm and the used tracking parameters whether a connection was observed. Most of the connections were weak and thus not usable for PTV definition. Only in one of the seven patients with a recurring tumor, a clear connection was present. It seems unlikely that DTI-based fiber tracking can be beneficial for predicting distant recurrences in the planning of PTVs for glioblastoma multiforme.

Intraoperative radiotherapy for glioblastoma: an international pooled analysis

PURPOSE

To report the results of the first international pooled analysis of patients with glioblastoma treated with intraoperative radiotherapy (IORT) in addition to standard of care therapy.

METHODS

Data from 51 patients treated at five centers in Germany, China and Peru were analyzed. All patients underwent tumor resection followed by a single application of IORT (10-40 Gy, prescribed to the applicator surface) with low-energy X-rays. Thereafter, standard adjuvant radiochemotherapy and maintenance chemotherapy were applied. Factors of interest were overall survival (OS), progression-free survival (PFS), local PFS (L-PFS; defined as appearance of new lesions ≤1 cm to the cavity border) and distant PFS (D-PFS; lesions >1 cm). The same endpoints were estimated at 1-, 2- and 3-years using the Kaplan-Meier method. Additionally, rates and severity (as per Common Terminology Criteria for Adverse Events Version 5.0) of radionecrosis (RN) were analyzed.

RESULTS

The median age was 55 years (range: 16-75) and the median Karnofsky Performance Status was 80 (20-100). At a median follow-up of 18.0 months (2-42.4), the median OS, PFS, L-PFS and D-PFS were 18.0 months (95% CI: 14.7-21.3), 11.4 months (95%CI: 7.58-15.22), 16 months (95%CI: 10.21-21.8) and 30.0 months (95%CI: 18.59 - 41.41), respectively. The estimated 1-, 2- and 3-year OS, PFS, L-PFS and D-PFS were 79.5%, 38.7% and 25.6%; 46.2%, 29.4%, and 5.9%; 60.9, 37.9%, and 12.6%; and 76.7%, 65.0%, and 39.0% respectively. First progression occurred locally in only 35.3% of cases. Grade 1 RN was detected in 7.8% and grade 3 in 17.6% of the patients. No grade 4 toxicity was reported and no treatment-related deaths occurred.

CONCLUSION

Compared to historical data, this pooled analysis suggests improved efficacy and safety of IORT with low-energy X-rays for newly diagnosed glioblastoma. Prospective data is warranted to confirm these findings.

Open-Label Phase II Evaluation of Imatinib in Primary Inoperable or Incompletely Resected and Recurrent Glioblastoma

PURPOSE

Preclinical studies indicated that imatinib may have single-agent activity in glioblastoma through inhibition of tyrosine kinase activity and also that it might enhance the efficacy of radiotherapy. We therefore sought to investigate clinical efficacy in patients with newly diagnosed and recurrent glioblastoma in combination with radiotherapy.

METHODS

We conducted a nonrandomized, 2-arm, open-label phase II trial including patients aged 18 years or older with an ECOG performance status of 0-2 that were either newly diagnosed (arm A) with a measurable tumor (i.e., after incomplete resection or biopsy) or that were diagnosed with progression of a glioblastoma after initial therapy (arm B). Patients in arm A received 600 mg/day imatinib in combination with hypofractionated radiotherapy (2.5 Gy per fraction, 22 fractions). Patients in arm B received 600 mg/day imatinib alone or in combination with re-irradiation at various doses. In case tumor progression occurred, CCNU was added (2 cycles, 100 mg/m2) to imatinib. The primary end point was progression-free survival (PFS). The secondary end point was safety, defined as per Common Terminology Criteria for Adverse Events (version 2.0). Overall survival (OS) was analyzed as an exploratory end point.

RESULTS

Fifty-one patients were enrolled, of which 19 were included in arm A and 32 in arm B. The median follow-up was 4 (0.5-30) months in arm A and 6.5 (0.3-51.5) months in arm B. The median PFS was 2.8 months (95% CI 0-8.7) in arm A and 2.1 months (95% CI 0-11.8) in arm B. The median OS was 5.0 (0.8-30) months (95% CI 0-24.1) in arm A and 6.5 (0.3-51.5) months (95% CI 0-32.5) in arm B. The major grade 3 events were seizure (present in 17 patients), pneumonia (11 patients), and vigilance decrease (7 patients).

CONCLUSIONS

Imatinib showed no measurable activity in patients with newly diagnosed or recurrent glioblastoma.

A Second Course of Radiotherapy in Patients with Recurrent Malignant Gliomas: Clinical Data on Re-irradiation, Prognostic Factors, and Usefulness of Digital Biomarkers

OPINION STATEMENT

The treatment of malignant gliomas has undergone a significant intensification during the past decade, and the interdisciplinary treatment team has learned that all treatment opportunities, including surgery and radiotherapy (RT), also have a central role in recurrent gliomas. Throughout the decades, re-irradiation (re-RT) has achieved a prominent place in the treatment of recurrent gliomas. A solid body of evidence supports the safety and efficacy of re-RT, especially when modern techniques are used, and justifies the early use of this regimen, especially in the case when macroscopic disease is present. Additionally, a second adjuvant re-RT to the resection cavity is currently being investigated by several investigators and seems to offer promising results. Although advanced RT technologies, such as stereotactic radiosurgery (SRS), fractionated stereotactic radiotherapy (FSRT), intensity-modulated radiotherapy (IMRT), and image-guided radiotherapy (IGRT) have become available in many centers, re-RT should continue to be kept in experienced hands so that they can select the optimal regimen, the ideal treatment volume, and the appropriate techniques from their tool-boxes. Concomitant or adjuvant use of systemic treatment options should also strongly be taken into consideration, especially because temozolomide (TMZ), cyclohexyl-nitroso-urea (CCNU), and bevacizumab have shown a good safety profile; they should be considered, if available. Nonetheless, the selection of patients for re-RT remains crucial. Single factors, such as patient age or the progression-free interval (PFI), fall too short. Therefore, powerful prognostic scores have been generated and validated, and these scores should be used for patient selection and counseling.

Appraisal of re-irradiation for the recurrent glioblastoma in the era of MGMT promotor methylation

Despite recent innovation in treatment techniques and subsequently improved outcomes, the majority of glioblastoma (GBL) have relapses, especially in locoregional areas. Local re-irradiation (re-RT) has been established as a feasible option for recurrent GBL of all ages with safety, tolerability, and effectiveness both in survival and quality of life regardless of fractionation schedule. To keep adverse effects under acceptable range, cumulative dose limit in equivalent dose at 2 Gy fractions by the linear-quadratic model at α/β = 2 for normal brain tissue (EQD2) with narrow margin should be observed and single/hypofractionated re-RT should be undertaken very carefully to recurrent tumor with large volume or adjacent to the brainstem. Promising outcome of re-operation (re-Op) plus re-RT (re-Op/RT) need to be validated and result from re-RT with temozolomide/bevacizumab (TMZ/BV) or new strategy is expected. Development of new-concept prognostic scoring or risk group is required to select patients properly and make use of predictive biomarkers such as O(6)-methylguanine-DNA methyltransferase (MGMT) promotor methylation that influence outcomes of re-RT, re-Op/RT, or re-RT with TMZ/BV.

Re-irradiation in elderly patients with glioblastoma: a single institution experience

BACKGROUND

Re-Irradiation (Re-RT) is an established treatment option for young patients with recurrent glioblastoma (GBM). Multiple reports show a low risk of side-effects as well as a good efficacy resulting in median survival times ranging from 5 to 18 months. Elderly patients, however, are underrepresented in reports about Re-RT. Even in the elderly, with concomitant radiochemotherapy and adjuvant chemotherapy, progression-free survival times now are approaching 6 months or even longer.

METHODS

We report on 25 consecutive patients with at least 65 years of age treated with Re-RT for recurrent GBM. We analyzed the patient's files for the treatment regimens, side-effects and survival times. Survival times, as well as hazards, were calculated by the Kaplan Meier method as well as Cox-regression method, respectively.

RESULTS

The median overall survival was 6.9 months, treatment was well tolerated with only minor side effects. Use of systemic treatments as well as the length of the interval between 1st -line radiotherapy and re-irradiation were associated with a favorable prognosis. The latter remained significant after multivariate analysis.

CONCLUSION

Re-RT of elderly GBM patients should not be withheld based purely on age since the treatment is safe and results in comparable survival times to younger patients. When counseling elderly patients with recurrent GBM, especially the length of the interval since 1st line radiotherapy should be considered as a prognostic factor and an additional systemic treatment option should be considered.

The algorithms of adjuvant therapy in gliomas and their effect on survival

The treatment of gliomas became more sophisticated during the last decades. As by now, adjuvant treatment after maximum safe resection is considered an important and effective treatment strategy in most gliomas, yet the decision is based on several factors. This review summarizes the available evidence for the current adjuvant treatment algorithms with a focus on the impact on the survival of glioma patients. The review is based on the current guidelines, but it also includes new insights which have not yet been included into the official guidelines.

Multimodal treatment for local recurrent malignant gliomas: Resurgery and/or reirradiation followed by chemotherapy

The therapeutic management of recurrent malignant gliomas (MGs) is not determined. Therefore, the efficacy of a multimodal approach and a combination systemic therapy was investigated. A retrospective analysis of 26 MGs patients at first relapse treated with multimodal therapy (chemotherapy plus surgery and/or reirradiation) or chemotherapy alone was performed. Second-line chemotherapy consisted of fotemustine (FTM) in combination with bevacizumab (BEV) (cFTM/BEV) or followed by third-line BEV (sFTM/BEV). Subgroup analyses were performed. Multimodal therapy provided a higher overall response rate (ORR) (73 vs. 47%), disease control rate (DCR) (82 vs. 67%), median progression-free survival (mPFS) (11 vs. 7 months; P=0.08) and median overall survival (mOS) (13 vs. 8 months; P=0.04) compared with chemotherapy. Concomitant FTM/BEV resulted in higher ORR (84 vs. 36%), DCR (92 vs. 57%), mPFS (10 vs. 5 months; P=0.22) and mOS (11 vs. 5.2 months; P=0.15) compared with sFTM/BEV. Methylated patients did not experience additional survival benefits with multimodality treatment but had higher mPFS (10 vs 7.1 months; P=0.33) and mOS (11 vs. 8 months; P=0.33) with cFTM/BEV. Unmethylated patients experienced the greatest survival benefit with the multimodal approach (mPFS: 10 vs. 5 months; mOS 11 vs 6 months; both P=0.02) and cFTM/BEV (mPFS: 5 vs. 2 months; mOS 6 vs. 3.2 months; both P=0.01). In conclusion, in recurrent MGs, multimodal therapy and cFTM/BEV provide survival and response benefits. Methylated patients benefit from a cFTM/BEV but not from a multimodal approach. Notably, unmethylated patients had the highest survival benefit with the two strategies.

CT-guided interstitial HDR-brachytherapy for recurrent glioblastoma multiforme: a 20-year single-institute experience

PURPOSE

To report our results of computed tomography-guided interstitial high-dose-rate (HDR) brachytherapy (BRT) in the treatment of patients with recurrent inoperable glioblastoma multiforme (GBM).

PATIENTS AND METHODS

Between 1995 and 2014, 135 patients were treated with interstitial HDR BRT for inoperable recurrent GBM located within previously irradiated volumes. Patient's median age was 57.1 years (14-82 years). All patients were pretreated with surgery, postoperative external beam radiation therapy (EBRT) and systemic chemotherapy (ChT). The median recurrent tumor volume was 42 cm³ (2-207 cm³). The prescribed HDR dose was median 40 Gy (30-50 Gy) delivered in twice-daily fractions of 5.0 Gy over consecutive days. No repeat surgery or ChT was administered in conjunction with BRT. Survival from BRT, progression-free survival (PFS), toxicity as well as the impact of several prognostic factors were evaluated.

RESULTS

At a median follow-up of 9.2 months, the median overall survival following BRT and the median PFS were 9.2 and 4.6 months, respectively. Of the prognostic variables evaluated in univariate analysis, extent of surgery at initial diagnosis, tumor volume at recurrence, as well as time from EBRT to BRT reached statistical significance, retained also in multivariate analysis. Eight patients (5.9%) developed treatment-associated complications including intracerebral bleeding in 4 patients (2.9%), symptomatic focal radionecrosis in 3 patients (2.2%), and severe convulsion in 1 patient (0.7%).

CONCLUSIONS

For patients with recurrent GBM, interstitial HDR BRT is an effective re-irradiation method for even larger tumors providing palliation without excessive toxicity.

Neuroimaging classification of progression patterns in glioblastoma: a systematic review

BACKGROUND

Our primary objective was to report the current neuroimaging classification systems of spatial patterns of progression in glioblastoma. In addition, we aimed to report the terminology used to describe 'progression' and to assess the compliance with the Response Assessment in Neuro-Oncology (RANO) Criteria.

METHODS

We conducted a systematic review to identify all neuroimaging studies of glioblastoma that have employed a categorical classification system of spatial progression patterns. Our review was registered with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) registry.

RESULTS

From the included 157 results, we identified 129 studies that used labels of spatial progression patterns that were not based on radiation volumes (Group 1) and 50 studies that used labels that were based on radiation volumes (Group 2). In Group 1, we found 113 individual labels and the most frequent were: local/localised (58%), distant/distal (51%), diffuse (20%), multifocal (15%) and subependymal/subventricular zone (15%). We identified 13 different labels used to refer to 'progression', of which the most frequent were 'recurrence' (99%) and 'progression' (92%). We identified that 37% (n = 33/90) of the studies published following the release of the RANO classification were adherent compliant with the RANO criteria.

CONCLUSIONS

Our review reports significant heterogeneity in the published systems used to classify glioblastoma spatial progression patterns. Standardization of terminology and classification systems used in studying progression would increase the efficiency of our research in our attempts to more successfully treat glioblastoma.

Timing of re-irradiation in recurrent high-grade gliomas: a single institution study

There is no standard treatment available for recurrent high-grade gliomas. This monoinstitutional retrospective analysis evaluates the differences in overall survival and progression-free survival in patients according to the timing of re-irradiation. Patients suffering from a glioblastoma who received re-irradiation for recurrence were evaluated retrospectively. The median overall survival (OS) and the median progression-free survival were compared with different treatment options and within various time periods. From January 2007 until March 2015, 41 patients suffering from recurrent high-grade gliomas received re-irradiation [median dose of 30.6 Gy (range 20-40 Gy) in median 4 Gy fractions (range 1.8-5 Gy)] in our institution after initial postoperative irradiation or combined radiochemotherapy. The OS in this population was 34 months, and the OS after recurrence (OS-R) was 13 months. After diagnosis of recurrence, patients underwent additional surgical resection after a median of 1.2 months, received a second-line systemic therapy after 2.2 months with or without re-irradiation after 5.7 months. Growth of the tumour was assessed 4.3 months after the start of re-irradiation. The OS after the second surgical resection was 12.2 months, 11.7 months after the start of the second-line systemic therapy, and 6.7 months after the start of re-irradiation. The OS-R was not significantly correlated with the start of re-irradiation after a diagnosis of recurrence or the time period after the previous surgery. At this institution, re-irradiation was performed later compared to other treatment options. However, select patients could benefit from irradiation at an earlier time point. A precise time point should still be evaluated on an individual basis due to the patient's diverse conditions.