Radiotherapy in low-grade glioma adult patients: a retrospective survival and neurocognitive toxicity analysis

Neuropsychological performances in patients with infiltrative non-GBM gliomas after postoperative adjuvant photon or proton radiotherapy: A prospective and preliminary investigation

Infiltrative non-GBM gliomas are common primary intracranial malignancies, and postoperative adjuvant radiotherapy is recommended for most adult patients diagnosed with this disease to enhance local control and prolong intracranial progression-free survival (PFS). However, RT-related neurocognitive function (NCF) consequences should not be ignored. Early neurocognitive decline principally includes episodic memory, associated significantly with functions of the hippocampus. This prospective study aims to investigate the impact of adjuvant brain irradiation on neurocognitive performances and relevant oncological outcomes.Twenty-five patients with intracranial infiltrative non-GBM gliomas were enrolled when postoperative adjuvant RT was recommended. All recruited patients should receive baseline brain magnetic resonance imaging, and neuropsychological assessments before and 4 months after the RT course. A battery of neuropsychological measures, mainly including executive functions, memory, psychomotor speed and visuoconstructive ability, was used to evaluate NCFs of interest.Analyzing the delta values between post-irradiation and baseline NCF scores, we observed a robust trend reflecting cognitive stabilization rather than deterioration in almost all NCF. Both verbal and visual memory functions exhibited significant differences in the corresponding scaled scores (Z = -2.722, p = .006, regarding verbal memory; Z = -2.246, p = .025, concerning non-verbal memory). Moreover, patients' neuropsychological performances associated with psychomotor speed and executive functions also disclosed a tendency toward stabilization/improvement.This prospective study demonstrated that patients with infiltrative non-GBM exhibited a marked tendency toward neurocognitive stabilization after receiving postoperative adjuvant RT. Clinical trial registration: Trial Registration with ClinicalTrials.gov identifier: NCT03534050.

Dosimetric comparison of hippocampal-sparing technologies in patients with low-grade glioma

Background

Radiotherapy (RT) plays an integral role in the management of low-grade gliomas (LGG). Late toxicity from RT can cause progressive neurocognitive dysfunction. Radiation-induced damage to the hippocampus (HCP) plays a considerable role in memory decline. Advancements in photon planning software have resulted in the development of multi-criteria optimization (MCO) and HyperArc technologies which may improve HCP sparing while maintaining planning target volume (PTV) target coverage.

Methods

Three planning methods for hippocampal sparing (HS) were compared, volumetric modulated arc therapy (VMAT) without HS (VMAT_noHS), VMAT with HS (VMAT_HS), MCO with HS (MCO_HS), and HyperArc with HS (HyperArc_HS).

Results

Twenty-five patients were identified. The contralateral HCP was spared in 16 patients and bilateral HCP in 9 patients with superiorly located tumors. All 3 HS planning techniques showed significant reductions in dose to the spared HCP in contralateral cases but only VMAT_HS and MCO_HS achieved this in bilateral cases (P < .008). Only MCO_HS was superior to VMAT_HS in lowering the dose to both contralateral HCP and bilateral HCP in all measured metrics (P < .008). PTV and OAR (organ at risk) dose constraints were achieved for all plans.

Conclusions

This retrospective dosimetric study demonstrated the feasibility of HS for low-grade glioma. All 3 HS planning techniques achieved significant dose reductions to the spared contralateral hippocampus, but only MCO_HS and VMAT_HS achieved this in bilateral cases. MCO was superior to other planning techniques for sparing both bilateral and contralateral hippocampi.

Dosimetry comparison with helical tomotherapy, volumetric modulated arc therapy, and intensity-modulated radiotherapy for grade II gliomas: A single‑institution case series

Radiotherapy is an essential postoperative treatment for grade II gliomas. However, comparative dosimetric studies of different radiotherapy plans for grade II gliomas are still lacking. Therefore, we conducted this case series analysis to compare the dosimetric differences among helical tomotherapy (TOMO), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT) for grade II gliomas. To achieve that, seven diagnosed postoperative patients with grade II gliomas were analyzed by computed tomography and then planned with TOMO, VMAT, and IMRT. The plan target volume (PTV) prescribed dose was 50 Gy (daily fraction of 2.0 Gy, 5 days/week). The expected treatment efficiency was measured by monitor units (MUs) scoring. Treatment plans of the patients were compared in the quality of target volumes dosage coverage, the efficiency of dosage delivery, and the dosage exposure of normal adjacent organs at risk (OAR). Differences in each method were measured by utilizing the Nonparametric ANOVA. The study shows that TOMO achieved a significantly higher PTV-D_98% (doses received by 98% of the PTV volume) than VMAT and IMRT (50.30 ± 0.13 vs 49.21 ± 0.19, p = 0.006; 50.30 ± 0.13 vs 49.78 ± 0.18, p = 0.014), while there was no difference in PTV-D_2% (doses received by 2% of the PTV volume). IMRT achieved a conformity index (CI) preferably, and TOMO generated a favorable homogeneity index (HI) (p < 0.05 for both). The MUs were fewer for VMAT than IMRT and TOMO (294 ± 19, 572 ± 24, 317 ± 97, respectively). IMRT achieved better protection for the lens and brain stems. Our case series study indicated that TOMO, VMAT, and IMRT achieved a comparatively good target dosimetric coverage, and most OARs were protected well. IMRT is not inferior to TOMO and VMAT and is still very suitable for treating most grade II glioma patients.

Evaluation of the Hippocampal Normal Tissue Complication Model in a Prospective Cohort of Low Grade Glioma Patients-An Analysis Within the EORTC 22033 Clinical Trial

Purpose: To evaluate the performance of the hippocampal normal tissue complication model that relates dose to the bilateral hippocampus to memory impairment at 18 months post-treatment in a population of low-grade glioma (LGG) patients.

Methods: LGG patients treated within the radiotherapy-only arm of the EORTC 22033-26033 trial were analyzed. Hippocampal dose parameters were calculated from the original radiotherapy plans. Difference in Rey Verbal Auditory Learning test delayed recall (AVLT-DR) performance pre-and 18 (±4) months post-treatment was compared to reference data from the Maastricht Aging study. The NTCP model published by Gondi et al. was applied to the dosimetric data and model predictions were compared to actual neurocognitive outcome.

Results: A total of 29 patients met inclusion criteria. Mean dose in EQD2 Gy to the bilateral hippocampus was 39.8 Gy (95% CI 34.3–44.4 Gy), the median dose to 40% of the bilateral hippocampus was 47.2 EQD2 Gy. The model predicted a risk of memory impairment exceeding 99% in 22 patients. However, only seven patients were found to have a significant decline in AVLT-dr score.

Conclusions: In this dataset of only LGG patients treated with radiotherapy the hippocampus NTCP model did not perform as expected to predict cognitive decline based on dose to 40% of the bilateral hippocampus. Caution should be taken when extrapolating this model outside of the range of dose-volume parameters in which it was developed.

Long-term neurocognitive and other side effects of radiotherapy, with or without chemotherapy, for glioma

BACKGROUND

Gliomas are brain tumours arising from glial cells with an annual incidence of 4 to 11 people per 100,000. In this review we focus on gliomas with low aggressive potential in the short term, i.e. low-grade gliomas. Most people with low-grade gliomas are treated with surgery and may receive radiotherapy thereafter. However, there is concern about the possible long-term effects of radiotherapy, especially on neurocognitive functioning.

OBJECTIVES

To evaluate the long-term neurocognitive and other side effects of radiotherapy (with or without chemotherapy) compared with no radiotherapy, or different types of radiotherapy, among people with glioma (where 'long-term' is defined as at least two years after diagnosis); and to write a brief economic commentary.

SEARCH METHODS

We searched the following databases on 16 February 2018 and updated the search on 14 November 2018: Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 11) in the Cochrane Library; MEDLINE via Ovid; and Embase via Ovid. We also searched clinical trial registries and relevant conference proceedings from 2014 to 2018 to identify ongoing and unpublished studies.

SELECTION CRITERIA

Randomised and non-randomised trials, and controlled before-and-after studies (CBAS). Participants were aged 16 years and older with cerebral glioma other than glioblastoma. We included studies where patients in at least one treatment arm received radiotherapy, with or without chemotherapy, and where neurocognitive outcomes were assessed two or more years after treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias. We assessed the certainty of findings using the GRADE approach.

MAIN RESULTS

The review includes nine studies: seven studies were of low-grade glioma and two were of grade 3 glioma. Altogether 2406 participants were involved but there was high sample attrition and outcome data were available for a minority of people at final study assessments. In seven of the nine studies, participants were recruited to randomised controlled trials (RCTs) in which longer-term follow-up was undertaken in a subset of people that had survived without disease progression. There was moderate to high risk of bias in studies due to lack of blinding and high attrition, and in two observational studies there was high risk of selection bias. Paucity of data and risk of bias meant that evidence was of low to very low certainty. We were unable to combine results in meta-analysis due to diversity in interventions and outcomes.The studies examined the following five comparisons.Radiotherapy versus no adjuvant treatmentTwo observational studies contributed data. At the 12-year follow-up in one study, the risk of cognitive impairment (defined as cognitive disability deficits in at least five of 18 neuropsychological tests) was greater in the radiotherapy group (risk ratio (RR) 1.95, 95% confidence interval (CI) 1.02 to 3.71; n = 65); at five to six years the difference between groups did not reach statistical significance (RR 1.38, 95% CI 0.92 to 2.06; n = 195). In the other study, one subject in the radiotherapy group had cognitive impairment (defined as significant deterioration in eight of 12 neuropsychological tests) at two years compared with none in the control group (very low certainty evidence).With regard to neurocognitive scores, in one study the radiotherapy group was reported to have had significantly worse mean scores on some tests compared with no radiotherapy; however, the raw data were only given for significant findings. In the second study, there were no clear differences in any of the various cognitive outcomes at two years (n = 31) and four years (n = 15) (very low certainty evidence).Radiotherapy versus chemotherapyOne RCT contributed data on cognitive impairment at up to three years with no clear difference between arms (RR 1.43, 95% CI 0.36 to 5.70, n = 117) (low-certainty evidence).High-dose radiotherapy versus low-dose radiotherapyOnly one of two studies reporting this comparison contributed data, and at two and five years there were no clear differences between high- and low-dose radiotherapy arms (very low certainty evidence).Conventional radiotherapy versus stereotactic conformal radiotherapyOne study involving younger people contributed limited data from the subgroup aged 16 to 25 years. The numbers of participants with neurocognitive impairment at five years after treatment were two out of 12 in the conventional arm versus none out of 11 in the stereotactic conformal radiotherapy arm (RR 4.62, 95% CI 0.25 to 86.72; n = 23; low-certainty evidence).Chemoradiotherapy versus radiotherapyTwo RCTs tested for cognitive impairment. One defined cognitive impairment as a decline of more than 3 points in MMSE score compared with baseline and reported data from 2-year (110 participants), 3-year (91 participants), and 5-year (57 participants) follow-up with no clear difference between the two arms at any time point. A second study did not report raw data but measured MMSE scores over five years in 126 participants at two years, 110 at three years, 69 at four years and 53 at five years. Authors concluded that there was no difference in MMSE scores between the two study arms (P = 0.4752) (low-certainty evidence).Two RCTs reported quality of life (QoL) outcomes for this comparison. One reported no differences in Brain-QoL scores between study arms over a 5-year follow-up period (P = 0.2767; no raw data were given and denominators were not stated). The other trial reported that the long-term results of health-related QoL showed no difference between the arms but did not give the raw data for overall HRQoL scores (low-certainty evidence).We found no comparative data on endocrine dysfunction; we planned to develop a brief economic commentary but found no relevant economic studies for inclusion.

AUTHORS' CONCLUSIONS

Radiotherapy for gliomas with a good prognosis may increase the risk of neurocognitive side effects in the long term; however the magnitude of the risk is uncertain. Evidence on long-term neurocognitive side effects associated with chemoradiotherapy is also uncertain. Neurocognitive assessment should be an integral part of long-term follow-up in trials involving radiotherapy for lower-grade gliomas to improve the certainty of evidence regarding long-term neurocognitive effects. Such trials should also assess other potential long-term effects, including endocrine dysfunction, and evaluate costs and cost effectiveness.

Repeat surgery for recurrent low-grade gliomas should be standard of care

The importance of surgery and maximal extent of resection (EOR) is well established in primary low-grade glioma (LGG) management. However, the role of surgery in the management of recurrent LGG is less clear. A recent review on the management of recurrent LGG concluded there was insufficient evidence to recommend surgery. Here, we summarize the recent advances regarding the role of surgery, radiotherapy (RT) and chemotherapy in the management of recurrent LGG. There is increasing evidence to support maximal EOR for treating recurrent LGG, as it may improve progression free survival (PFS) after recurrence and overall survival (OS). Based on the studies presented in this review, we suggest that repeat surgery with maximal EOR should be standard of care for recurrent LGG treatment.

Neurocognitive Function Following Therapy for Low-Grade Gliomas

Low-grade gliomas (LGGs) are a heterogenous group of primary brain neoplasms that most commonly occur in children and young adults, characterized by a slow, indolent course and overall favorable prognosis. Standard therapies used to treat LGGs have included surgical resection, radiotherapy, chemotherapy, or a combination thereof. Given the anticipated long survival and typical young age of patients with LGG, the long-term sequelae of therapy require special attention, especially as they affect neurocognitive function and quality of life. We review the complex interplay of baseline and treatment-related factors that perturb neurocognition as well as the effect of each treatment modality on altering neurocognitive outcomes in this patient population.