Clinical relevance of the radiation dose bath in lower grade glioma, a cross-sectional pilot study on neurocognitive and radiological outcome

The effect of radiation dose to the brain on early self-reported cognitive function in brain and head-and-neck cancer patients

Purpose

Assess cognitive changes after radiotherapy (RT) in brain and head-and-neck (HN) cancer patients using patient-reported outcome measures (PROMs) and evaluate a dose-effect relationship for brain structures.

Materials and methods

Primary brain and HN cancer patients treated with RT between 2012-2021 were included. Patient characteristics, clinical parameters, and PROMs at baseline and 1-year follow-up were collected. Cognitive functioning (CF) from the EORTC QLQ-C30, communication deficit (CD) from the QLQ-BN20, and one cognition-related questions from the EQ6D questionnaire were used, the latter two only for brain patients. Missing data were imputed and the four-point scale scores were transformed to a 100-point scale. Change in scores from baseline to 1-year were categorized into improvement/constant or deterioration. Organs-at-risk (OARs) were contoured either clinically or retrospectively using autocontouring and dose to the OARs were calculated.

Results

A total of 110 brain and 356 HN cancer patients were included. Median age was 56 (brain) and 67.5 (HN) years. Baseline and 1-year CF was significantly lower for brain patients (p < 0.001). Univariate analysis for ΔCF showed that age at start RT ≤ 65 years, receiving chemotherapy, higher CF Baseline score, brain mean dose > 3 Gy, and multiple dose levels to left and right hippocampus were statistically associated with cognitive deterioration. Multivariate analysis for ΔCF identified age at RT ≤ 65 years, higher CF Baseline score, and brain mean dose > 3 Gy as significant predictors.

Conclusion

This study identified risk factors for subjective cognitive decline and suggests that patients' self-perceived cognitive deterioration may be related to age, CF baseline score and brain radiation dose above 3 Gy.

Trajectory of long-term neuropsychological performances and cognitive-deterioration-free survival after hippocampus-sparing whole-brain radiotherapy in cancer patients mostly with newly diagnosed brain oligometastases

Neurocognitive functions (NCFs) might change after conventional whole-brain radiotherapy (WBRT). The technique of hippocampus sparing during WBRT (HS-WBRT) may substantially preserve NCFs. Therefore, the aim of this study was to examine whether trajectories of neuropsychological performances maintained or improved after HS-WBRT. A total of 125 cancer patients underwent the HS-WBRT course. Before HS-WBRT, all participants underwent multidomain neurocognitive assessment, mainly involving executive functions and hippocampus-related memory. After radiotherapy, the above assessment was administered at regular time points to monitor longitudinal neuropsychological performances. The delta values of post-radiotherapy and baseline NCF scores showed a sustained trend, signifying cognitive maintenance rather than deterioration. This trend was observed for hippocampus-related verbal memory and frontal-lobe-related executive functions, represented by the score of Word List-immediate memory and Modified Card Sorting Test - Complete Categories, respectively. The potential predictors of longitudinal multidomain neuropsychological performances included age at enrollment, baseline NCF scores, and the assessment time (months) elapsed since enrollment, signifying the trajectory of patients' neuropsychological performances after HS-WBRT. Among longitudinal neuropsychological outcomes, there was a considerable time trend toward maintenance in verbal learning immediate memory [odds ratio, 1.112, 95% confidence interval, 1.08 - 1.15], which persisted even after adjusting for the most independent predictor (baseline NCF scores). Functional preservation of longitudinal multidomain neuropsychological performances was evident after HS-WBRT. Such neurocognitive preservation, particularly hippocampus-related memory functions, was meaningfully sustained in our patients after undergoing the standardized course of hippocampus sparing during WBRT.

Longitudinal brain volumetrics in glioma survivors

OBJECTIVE

Radiation therapy (RT) is used selectively for patients with low-grade glioma (LGG) given the concerns for potential cognitive effects in survivors, but prior cognitive outcome studies among LGG survivors have had inconsistent findings. Translational studies that characterize changes in brain anatomy and physiology after treatment of LGG may help to both contextualize cognitive findings and improve the overall understanding of radiation effects in normal brain tissue. This study aimed to investigate the hypothesis that patients with LGG who are treated with RT will experience greater brain volume loss than those who do not receive RT.

METHODS

This retrospective longitudinal study included all patients with WHO grade 2 glioma who received posttreatment surveillance MRI at the University of Alabama at Birmingham. Volumetric analysis of contralateral cortical white matter (WM), cortical gray matter (GM), and hippocampus was performed on all posttreatment T1-weighted MRI sequences using the SynthSeg script. The effect of clinical and treatment variables on brain volumes was assessed using two-level hierarchical linear models.

RESULTS

The final study cohort consisted of 105 patients with 1974 time points analyzed. The median length of imaging follow-up was 4.6 years (range 0.36-18.9 years), and the median number of time points analyzed per patient was 12 (range 2-40). Resection was performed in 79 (75.2%) patients, RT was administered to 61 (58.1%) patients, and chemotherapy was administered to 66 (62.9%) patients. Age at diagnosis (β = -0.06, p < 0.001) and use of RT (β = -1.12, p = 0.002) were associated with the slope of the contralateral cortical GM volume model (i.e., change in GM over time). Age at diagnosis (β = -0.08, p < 0.001), midline involvement (β = 1.31, p = 0.006), and use of RT (β = -1.45, p = 0.001) were associated with slope of the contralateral cortical WM volume model. Age (β = -0.0027, p = 0.001), tumor resection (β = -0.069, p < 0.001), use of chemotherapy (β = -0.0597, p = 0.003), and use of RT (β = -0.0589, p < 0.001) were associated with the slope of the contralateral hippocampus volume model.

CONCLUSIONS

This study demonstrated volume loss in contralateral brain structures among LGG survivors, and patients who received RT experienced greater volume loss than those who did not. The results of this study may help to provide context for cognitive outcome research in LGG survivors and inform the design of future strategies to preserve cognition.

Volumetric brain assessment of long-term head and neck cancer survivors

BACKGROUND

Radiation therapy (RT) for locally advanced head and neck cancer (HNC) often exposes subcortical brain structures to radiation. We performed this study to assess region-specific brain volumetrics in a population of long term HNC survivors.

METHODS AND MATERIALS

Forty HNC survivors were enrolled at a mean of 6.4 years from completion of RT. Patients underwent a research MRI protocol that included a 3D T1- weighted whole-brain scan on a 3 Tesla MRI scanner. Voxel based morphometry was performed using the Computational Anatomy Toolbox with the Neuromorphometrics atlas. Healthy controls from the Human Connectome Project were used as a comparison cohort. Study participants also completed a comprehensive neurocognitive assessment.

RESULTS

The final study cohort consisted of 38 participants after excluding 2 participants due to image quality. HNC survivors displayed widespread reduction in gray matter (GM) brain region volumes that included bilateral medial frontal cortex, temporal lobe, hippocampus, supplemental motor area, and cerebellum. Greater radiation exposure was associated with reduced GM volume in the left ventral diencephalon (r = -0.512, p = 0.003). Associations between cognition and regional GM volumes were identified for motor coordination and bilateral cerebellum (left, r = 0.444, p = 0.009; right, r = 0.372, p = 0.030), confrontation naming and left amygdala (r = 0.382, p = 0.026), verbal memory and bilateral thalamus (left, r = 0.435, p = 0.010; right, r = 0.424, p = 0.012), right amygdala (r = 0.339, p = 0.050), and right putamen (r = 0.364, p = 0.034).

CONCLUSIONS

Reductions in GM were observed within this cohort of primarily non-nasopharyngeal HNC survivors as compared to a control sample. GM volumes were associated with performance in multiple cognitive domains. Results of this exploratory study support the need for investigation of anatomic brain changes as an important translational corollary to cognitive problems among HNC survivors.

Unilateral hippocampal sparing during whole brain radiotherapy for multiple brain metastases: narrative and critical review

Background

The landscape of brain metastases radiotherapy is evolving, with a shift away from whole-brain radiotherapy (WBRT) toward targeted stereotactic approaches aimed at preserving neurocognitive functions and maintaining overall quality of life. For patients with multiple metastases, especially in cases where targeted radiotherapy is no longer feasible due to widespread dissemination, the concept of hippocampal sparing radiotherapy (HA_WBRT) gains prominence.

Methods

In this narrative review we explore the role of the hippocampi in memory formation and the implications of their postradiotherapy lateral damage. We also consider the potential advantages of selectively sparing one hippocampus during whole-brain radiotherapy (WBRT). Additionally, by systematic evaluation of relevant papers published on PubMed database over last 20 years, we provide a comprehensive overview of the various changes that can occur in the left or right hippocampus as a consequence of radiotherapy.

Results

While it is important to note that various neurocognitive functions are interconnected throughout the brain, we can discern certain specialized roles of the hippocampi. The left hippocampus appears to play a predominant role in verbal memory, whereas the right hippocampus is associated more with visuospatial memory. Additionally, the anterior part of the hippocampus is more involved in episodic memory and emotional processing, while the posterior part is primarily responsible for spatial memory and pattern separation. Notably, a substantial body of evidence demonstrates a significant correlation between post-radiotherapy changes in the left hippocampus and subsequent cognitive decline in patients.

Conclusion

In the context of individualized palliative radiotherapy, sparing the unilateral (specifically, the left, which is dominant in most individuals) hippocampus could expand the repertoire of strategies available for adapted WBRT in cases involving multiple brain metastases where stereotactic radiotherapy is not a viable option. Prospective ongoing studies assessing various memory-sparing radiotherapy techniques will define new standard of radiotherapy care of patients with multiple brain metastases.

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.