Radiation response of the central nervous system

Memantine to Reduce Cognitive Impairment After Radiation in Children: A Pilot Study Evaluating the Feasibility of Memantine in Reducing Cognitive Impairment in Pediatric Patients after Radiation Therapy for Central Nervous System Tumors

PURPOSE

Memantine is standard in certain adults receiving brain radiation therapy (RT) to decrease cognitive impacts, but it is unknown whether pediatric patients can take, tolerate, and/or benefit from memantine. In this prospective single-arm feasibility study, we hypothesized that pediatric patients receiving central nervous system (CNS) RT would tolerate memantine with good adherence.

METHODS AND MATERIALS

Patients aged 4 to 18 years with a primary CNS malignancy (excluding World Health Organization grade 4 astrocytoma, glioblastoma) receiving intracranial RT were eligible. A 6-month memantine course was given during and after RT, with dose titration in 5 mg increments over 4 weeks targeting a weight-based maximum (0.4 mg/kg to the closest 5 mg), not to exceed 10 mg twice a day. The primary endpoint was to achieve 80% drug adherence rate in 80% of patients measured 1 month after RT. Secondary objectives included memantine feasibility at 3 and 6 months.

RESULTS

Eighteen patients enrolled from 2020 to 2022 and were prescribed memantine with RT. The study closed early to avoid competing with the phase 3 randomized Children's Oncology Group study ACCL2031. No predefined stopping rules were met. One patient withdrew for cognition-altering substance use, leaving 17 patients available for analysis. One patient discontinued memantine after one dose due to nausea. For the remaining 16 patients, there was a median of 100% pill completion rate (range, 74%-100%; n = 9/17 with 100% adherence) at 1 month after RT, with 15/16 (94%) with adherence rates >80%. At the 3- and 6-month post-RT time points for secondary endpoints, the median adherence rates were 100% (range, 55%-100%) and 96% (range, 33%-100%), respectively. Grade 1 to 2 fatigue, headache, and nausea were the most common toxicity events, at least possibly related to the study drug (n = 27), without attributable grade 3+ events.

CONCLUSIONS

Memantine is a feasible, safe, and well-tolerated addition to multimodality treatment for pediatric CNS malignancies. Results of ACCL2031 are awaited to define the value of memantine in this population.

Spinal chordoma and chondrosarcoma treatment experiences - a 20-year retrospective study from databases of two medical centers

The research retrospectively analyzed cases of spinal chordoma and chondrosarcoma involving patients who received treatment at the two hospitals between 2001 and 2023. Among the 48 patients studied (39 chordoma and 9 chondrosarcoma cases), the average age was 53.9 ± 15.8 years, with a range of 17 to 86 years. Out of these patients, 43 underwent excision surgery and were categorized based on tumor margin into negative (R0) or microscopically positive (R1) margin (n = 14) and macroscopically positive (R2) margin (n = 29) groups. The mean overall survival (OS) for R0/R1 and R2 groups was 156.5 ± 19.3 and 79.2 ± 11.9 months, respectively (p value = 0.012). The mean progression-free survival (PFS) for R0/R1 and R2 was 112.9 ± 24.4 and 25.5 ± 5.5 months (p value < 0.001). The study showed that regardless of whether patients in the R0/R1 or R2 groups received radiation therapy (RT) or not, there was no significant improvement in OS or PFS. Specifically, the OS and PFS for the RT only group were 75.9 ± 16.6 and 73.3 ± 18.0 months. In conclusion, the recommended treatment approach for spinal chordoma and chondrosarcoma remains en bloc resection surgery with an appropriate margin. Patients who are unsuitable for or decline surgery may find a beneficial disease control rate with traditional external beam photon/proton therapy.

Brain and Brain Stem Necrosis After Reirradiation for Recurrent Childhood Primary Central Nervous System Tumors: A PENTEC Comprehensive Review

PURPOSE

Reirradiation is increasingly used in children and adolescents/young adults (AYA) with recurrent primary central nervous system tumors. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) reirradiation task force aimed to quantify risks of brain and brain stem necrosis after reirradiation.

METHODS AND MATERIALS

A systematic literature search using the PubMed and Cochrane databases for peer-reviewed articles from 1975 to 2021 identified 92 studies on reirradiation for recurrent tumors in children/AYA. Seventeen studies representing 449 patients who reported brain and brain stem necrosis after reirradiation contained sufficient data for analysis. While all 17 studies described techniques and doses used for reirradiation, they lacked essential details on clinically significant dose-volume metrics necessary for dose-response modeling on late effects. We, therefore, estimated incidences of necrosis with an exact 95% CI and qualitatively described data. Results from multiple studies were pooled by taking the weighted average of the reported crude rates from individual studies.

RESULTS

Treated cancers included ependymoma (n = 279 patients; 7 studies), medulloblastoma (n = 98 patients; 6 studies), any CNS tumors (n = 62 patients; 3 studies), and supratentorial high-grade gliomas (n = 10 patients; 1 study). The median interval between initial and reirradiation was 2.3 years (range, 1.2-4.75 years). The median cumulative prescription dose in equivalent dose in 2-Gy fractions (EQD22; assuming α/β value = 2 Gy) was 103.8 Gy (range, 55.8-141.3 Gy). Among 449 reirradiated children/AYA, 22 (4.9%; 95% CI, 3.1%-7.3%) developed brain necrosis and 14 (3.1%; 95% CI, 1.7%-5.2%) developed brain stem necrosis with a weighted median follow-up of 1.6 years (range, 0.5-7.4 years). The median cumulative prescription EQD22 was 111.4 Gy (range, 55.8-141.3 Gy) for development of any necrosis, 107.7 Gy (range, 55.8-141.3 Gy) for brain necrosis, and 112.1 Gy (range, 100.2-117 Gy) for brain stem necrosis. The median latent period between reirradiation and the development of necrosis was 5.7 months (range, 4.3-24 months). Though there were more events among children/AYA undergoing hypofractionated versus conventionally fractionated reirradiation, the differences were not statistically significant (P = .46).

CONCLUSIONS

Existing reports suggest that in children/AYA with recurrent brain tumors, reirradiation with a total EQD22 of about 112 Gy is associated with an approximate 5% to 7% incidence of brain/brain stem necrosis after a median follow-up of 1.6 years (with the initial course of radiation therapy being given with conventional prescription doses of ≤2 Gy per fraction and the second course with variable fractionations). We recommend a uniform approach for reporting dosimetric endpoints to derive robust predictive models of late toxicities following reirradiation.

Primary Hypothyroidism in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

From the Pediatric Normal Tissue Effects in the Clinic (PENTEC) initiative, a systematic review and meta-analysis of publications reporting on radiation dose-volume effects for risk of primary hypothyroidism after radiation therapy for pediatric malignancies was performed.

METHODS AND MATERIALS

All studies included childhood cancer survivors, diagnosed at age <21 years, whose radiation therapy fields exposed the thyroid gland and who were followed for primary hypothyroidism. Children who received pituitary-hypothalamic or total-body irradiation were excluded. PubMed and the Cochrane Library were searched for studies published from 1970 to 2017. Data on age at treatment, patient sex, radiation dose to neck or thyroid gland, specific endpoints for hypothyroidism that were used in the studies, and reported risks of hypothyroidism were collected. Radiation dose-volume effects were modeled using logistic dose response. Relative excess risk of hypothyroidism as a function of age at treatment and sex was assessed by meta-analysis of reported relative risks (RR) and odds ratios.

RESULTS

Fifteen publications (of 1709 identified) were included for systematic review. Eight studies reported data amenable for dose-response analysis. At mean thyroid doses of 10, 20, and 30 Gy, predicted rates of uncompensated (clinical) hypothyroidism were 4%, 7%, and 13%, respectively. Predicted rates of compensated (subclinical) hypothyroidism were 12%, 25%, and 44% after thyroid doses of 10, 20, and 30 Gy, respectively. Female sex (RR = 1.7, P < .0001) and age >15 years at radiation therapy (RR = 1.3, P = .005) were associated with higher risks of hypothyroidism. After a mean thyroid dose of 20 Gy, predicted risks of hypothyroidism were 13% for males <14 years of age, increasing to 29% for females >15 years of age.

CONCLUSION

A radiation dose response for risk of hypothyroidism is evident; a threshold radiation dose associated with no risk is not observed. Thyroid dose exposure should be minimized when feasible. Data on hypothyroidism after radiation therapy should be better reported to facilitate pooled analyses.

Predictive Factors Associated With Radiation Myelopathy in Pediatric Patients With Cancer: A PENTEC Comprehensive Review

PURPOSE

Radiation myelitis (RM) is a rare complication of radiation therapy (RT). The Pediatric Normal Tissue Effects in the Clinic spinal cord task force aimed to identify RT dose effects and assess risk factors for RM in children. Through systematic review, we analyzed RT dose, fraction size, latency between completion of RT and toxicity, chemotherapy use, age when irradiated, and sex.

METHODS AND MATERIALS

We conducted literature searches of peer-reviewed manuscripts published from 1964 to June 2017 evaluating RM among children. Normality of variables was assessed with Kolmogorov-Smirnov or Shapiro-Wilk tests. Spearman's rank correlation coefficients were used to test correlations between RT dose/fraction size and latency between RT and development of toxicity.

RESULTS

Of 1329 identified and screened reports, 144 reports were fully reviewed and determined to have adequate data for analysis; 16 of these reports had a total of 33 cases of RM with a median age of 13 years (range, 0.2-18) at the time of RT. The most common primary tumor histologies were rhabdomyosarcoma (n = 9), medulloblastoma (n = 5), and Hodgkin lymphoma (n = 2); the most common chemotherapy agents given were vincristine (n = 15), intrathecal methotrexate (n = 12), and intrathecal cytarabine (n = 10). The median RT dose and fraction size were 40 Gy (range, 24-57.4 Gy) and 1.8 Gy (range, 1.3-2.6 Gy), respectively. RT dose resulting in RM in patients who also received chemotherapy was lower than in those not receiving chemotherapy (mean 39.6 vs 49.7 Gy; P = .04). There was no association of age with RT dose. The median latency period was 7 months (range, 1-29). Higher RT dose was correlated with longer latency periods (P = .03) to RM whereas sex, age, fraction size, and chemotherapy use were not. Two of 17 patients with adequate follow-up recovered from RM; unfortunately, it was fatal in 6 of 15 evaluable patients. Complication probability modeling was not possible because of the rarity of events.

CONCLUSIONS

This report demonstrates a relatively short latency from RT (with or without chemotherapy) to RM and a wide range of doses (including fraction sizes) associated with RM. No apparent association with age at the time of RT could be discerned. Chemotherapy appears to reduce spinal cord tolerance. Recovery from RM is rare, and it is often fatal.

Metabolic and Toxic Myelopathies

OBJECTIVE

This article reviews the clinical presentation, diagnostic evaluation, and treatment of metabolic and toxic myelopathies resulting from nutritional deficiencies, environmental and dietary toxins, drugs of abuse, systemic medical illnesses, and oncologic treatments.

LATEST DEVELOPMENTS

Increased use of bariatric surgery for obesity has led to higher incidences of deficiencies in nutrients such as vitamin B12 and copper, which can cause subacute combined degeneration. Myelopathies secondary to dietary toxins including konzo and lathyrism are likely to become more prevalent in the setting of climate change leading to drought and flooding. Although modern advances in radiation therapy techniques have reduced the incidence of radiation myelopathy, patients with cancer are living longer due to improved treatments and may require reirradiation that can increase the risk of this condition. Immune checkpoint inhibitors are increasingly used for the treatment of cancer and are associated with a wide variety of immune-mediated neurologic syndromes including myelitis.

ESSENTIAL POINTS

Metabolic and toxic causes should be considered in the diagnosis of myelopathy in patients with particular clinical syndromes, risk factors, and neuroimaging findings. Some of these conditions may be reversible if identified and treated early, requiring careful history, examination, and laboratory and radiologic evaluation for prompt diagnosis.

Obtaining organ-specific radiobiological parameters from clinical data for radiation therapy planning of head and neck cancers

Objective.Different radiation therapy (RT) strategies, e.g. conventional fractionation RT (CFRT), hypofractionation RT (HFRT), stereotactic body RT (SBRT), adaptive RT, and re-irradiation are often used to treat head and neck (HN) cancers. Combining and/or comparing these strategies requires calculating biological effective dose (BED). The purpose of this study is to develop a practical process to estimate organ-specific radiobiologic model parameters that may be used for BED calculations in individualized RT planning for HN cancers.Approach.Clinical dose constraint data for CFRT, HFRT and SBRT for 5 organs at risk (OARs) namely spinal cord, brainstem, brachial plexus, optic pathway, and esophagus obtained from literature were analyzed. These clinical data correspond to a particular endpoint. The linear-quadratic (LQ) and linear-quadratic-linear (LQ-L) models were used to fit these clinical data and extract relevant model parameters (alpha/beta ratio, gamma/alpha,dTand BED) from the iso-effective curve. The dose constraints in terms of equivalent physical dose in 2 Gy-fraction (EQD2) were calculated using the obtained parameters.Main results.The LQ-L and LQ models fitted clinical data well from the CFRT to SBRT with the LQ-L representing a better fit for most of the OARs. The alpha/beta values for LQ-L (LQ) were found to be 2.72 (2.11) Gy, 0.55 (0.30) Gy, 2.82 (2.90) Gy, 6.57 (3.86) Gy, 5.38 (4.71) Gy, and the dose constraint EQD2 were 55.91 (54.90) Gy, 57.35 (56.79) Gy, 57.54 (56.35) Gy, 60.13 (59.72) Gy and 65.66 (64.50) Gy for spinal cord, optic pathway, brainstem, brachial plexus, and esophagus, respectively. Additional two LQ-L parametersdTwere 5.24 Gy, 5.09 Gy, 7.00 Gy, 5.23 Gy, and 6.16 Gy, and gamma/alpha were 7.91, 34.02, 8.67, 5.62 and 4.95.Significance.A practical process was developed to extract organ-specific radiobiological model parameters from clinical data. The obtained parameters can be used for biologically based radiation planning such as calculating dose constraints of different fractionation regimens.

Whole brain radiation therapy resulting in radionecrosis: a possible link with radiosensitising chemoimmunotherapy

Radionecrosis describes a rare but serious complication of radiation therapy. In clinical practice, stereotactic radiosurgery (SRS) is increasingly used in combination with systemic therapy, including chemotherapy, immune checkpoint inhibitor and targeted therapy, either concurrently or sequentially. There is a paucity of literature regarding radionecrosis in patients receiving whole brain radiation therapy (WBRT) alone (without additional SRS) in combination with immunotherapy or targeted therapies. It is observed that certain combinations increase the overall radiosensitivity of the tumorous lesions. We present a rare case of symptomatic radionecrosis almost 1 year after WBRT in a patient with non-squamous non-small cell lung cancer on third-line chemoimmunotherapy. We discuss available research regarding factors that may lead to radionecrosis in these patients, including molecular and genetic profiles, specific drug therapy combinations and their timing or increased overall survival.

Dosimetric comparison of four radiotherapy techniques for stage III non‑small cell lung cancer

The present study was implemented to compare the dosimetric parameters of the target dose coverage and critical structures in the treatment planning of four radiotherapy techniques [namely, three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), hybrid IMRT (h-IMRT) and volumetric-modulated arc therapy (VMAT)] for stage III non-small cell lung cancer (NSCLC) qualified plans for medical physicists, therapists and physicians. A total of 40 patients confirmed to have stage IIIA or IIIB NSCLC were enrolled, and four plans were designed for each patient. The prescription dose to the planning target volume (PTV) was assigned as 60 Gy in 30 fractions. The conformity index (CI), heterogeneity index (HI) and parameters of organs at risk (OARs) were calculated. For the PTV, the CI for VMAT was found to be the highest of all the four techniques (P<0.05), whereas the HI for the h-IMRT technique was found to be the lowest (P<0.05). Concerning the OARs, for the percentage of lung volume receiving a dose >5 Gy (lung V₅), the highest value was obtained with VMAT (P<0.05), whereas for lung V₃₀ and heart V₃₀, the VMAT and IMRT techniques were found to be better compared with 3D-CRT and h-IMRT (P<0.05). For esophagus V₅₀, the maximal dose (D_max) and mean dose for the IMRT technique displayed the best results (P<0.05), and in the case of the spinal cord, the D_max with VMAT showed a significant advantage over the other techniques (P<0.05). The treatment monitor units (MUs) in IMRT were found to be the largest (P<0.05), whereas the treatment time with VMAT was the shortest (P<0.05). For smaller PTVs, VMAT was the technique that provided the optimal dose distribution and sparing of the heart. Compared with 3D-CRT alone, adding 20% IMRT to the 3D-CRT base plan was shown to improve the plan quality, and IMRT and VMAT, as techniques, had better dose coverage and sparing of OARs. Furthermore, for patients in whom the lung V5 could be kept low enough, VMAT potentially offered a good alternative to the technique to IMRT, thereby offering additional possibilities for sparing of other OARs, and decreasing the MUs and treatment time.

Efficacy and toxicity of primary re-irradiation for malignant spinal cord compression based on radiobiological modelling: a phase II clinical trial

BACKGROUND

The efficacy and safety of primary re-irradiation for MSCC are not known. Our aim was to establish the efficacy and safety of biologically effective dose-based re-irradiation.

METHODS

Patients presenting with MSCC at a previously irradiated spine segment, and not proceeding with surgical decompression, were eligible. A 3 Gray per fraction experimental schedule (minimum 18 Gy/6 fractions, maximum 30 Gy/10 fractions) was used, delivering a maximum cumulative spinal dose of 100 Gy2 if the interval since the last radiotherapy was within 6 months, or 130 Gy2 if longer. The primary outcome was a change in mobility from week 1 to week 5 post-treatment, as assessed by the Tomita score. The RTOG SOMA score was used to screen for spinal toxicity, and an MRI performed to assess for radiation-induced myelopathy (RIM).

RESULTS

Twenty-two patients were enroled, of whom eleven were evaluable for the primary outcome. Nine of eleven (81.8%) had stable or improved Tomita scores at 5 weeks. One of eight (12.5%) evaluable for late toxicity developed RIM.

CONCLUSIONS

Re-irradiation is an efficacious treatment for MSCC. There is a risk of RIM with a cumulative dose of 120 Gy2.

CLINICAL TRIAL REGISTRATION

Cancer Trials Ireland (ICORG 07-11); NCT00974168.

Effectiveness of 6D couch with daily cone beam computed tomography in reducing PTV margins for glioblastoma multiforme

Objectives

Image-guided radiotherapy maximizes therapeutic index of brain irradiation by reducing setup errors during treatment. The aim of study was to analyze setup errors in the radiation treatment of glioblastoma multiforme and if decrease in planning target volume (PTV), margin is feasible using daily cone beam CT (CBCT) and 6D couch correction.

Materials and Methods

Twenty-one patients (630 fractions of radiotherapy) were studied in which corrections were made in 6° of freedom. We determined setup errors, impact of setup errors of initial three fractions CBCT versus rest of the treatment with daily CBCT, and mean difference in setup errors with or without application of 6D couch and volumetric benefit of reduction of PTV margin from 0.5 cm to 0.3 cm.

Results

The mean shift in the conventional directions, namely, vertical, longitudinal, and lateral was 0.17 cm, 0.19 cm, and 0.11 cm. There was significant change in vertical shift when first three fractions were compared with rest of the treatment with daily CBCT. When the effect of 6D couch was nullified, all directions showed increased error with longitudinal shift being significant. The number of setup errors of magnitude >0.3 cm was more significant when only conventional shifts were applied as compared with 6D couch. There was significant decrease in volume of brain parenchyma irradiated when margin of PTV was reduced from 0.5 cm to 0.3 cm.

Conclusion

Daily CBCT along with 6D couch correction can reduce setup error which allows reduction in PTV margin during radiotherapy planning in turn improving the therapeutic index.

Safety and Efficacy of Dose-Escalated Radiation Therapy With a Simultaneous Integrated Boost for the Treatment of Spinal Metastases

PURPOSE

Intensity modulated radiation therapy (RT) for spine metastases using a simultaneous integrated boost (SSIB) was shown as an alternative to the treatment of select osseous metastases that are not amenable to spine stereotactic radiosurgery. We sought to update our clinical experience using SSIB in patients for whom dose escalation was warranted but spine stereotactic radiosurgery was not feasible.

METHODS AND MATERIALS

A total of 58 patients with 63 spinal metastatic sites treated with SSIB between 2012 and 2021 were retrospectively reviewed. The gross tumor volume and clinical target volume were prescribed 40 and 30 Gy in 10 fractions, respectively.

RESULTS

The median follow-up time was 31 months. Of 79% of patients who reported pain before RT with SSIB, 82% reported an improvement following treatment. Patient-reported pain scores on a 10-point scale revealed a significant decrease in pain at 1, 3, 6, and 12 months after SSIB (P < .0001). Additionally, there were limited toxicities; only 1 patient suffered grade 3 toxicity (pain) following RT. There were no reports of radiation-induced myelopathy at last follow-up, and 8 patients (13%) experienced a vertebral column fracture post-treatment. Local control was 88% (95% confidence interval [CI], 80%-98%) and 74% (95% CI, 59%-91%) at 1 and 2 years, respectively. Overall survival was 64% (95% CI, 53%-78%) and 45% (95% CI, 34%-61%) at 1 and 2 years, respectively. The median overall survival was 18 months (95% CI, 13-27 months). Multivariable analysis using patient, tumor, and dosimetric characteristics revealed that a higher Karnofsky performance status before RT (hazard ratio, 0.44, 0.22-0.89; P = .02) was associated with longer survival.

CONCLUSIONS

These data demonstrate excellent pain relief and local control with limited acute toxicities following treatment with RT using SSIB to 40 Gy. Collectively, our data suggest that dose escalation to spine metastases using SSIB can be safe and efficacious for patients, especially those with radioresistant disease. Further investigation is warranted to validate these findings.

A shortened whole brain radiation therapy protocol for meningoencephalitis of unknown origin in dogs

Introduction

A variety of treatment options have been described for canine meningoencephalitis of unknown origin (MUO). Few studies focused on radiation therapy as a second line immunomodulating treatment, implicating its effective use. However, a standard radiation therapy protocol is lacking, and further research will help to evaluate the effect of different dose regimens.

Methods

Ten dogs diagnosed with MUO based on MRI and CSF findings were prospectively enrolled. The dogs were treated with a shortened whole brain radiation therapy protocol (5 × 4 Gy) in combination with prednisolone. Neurologic changes were quantified using an established scoring scheme. Follow-up MRI and CSF examination was scheduled three months after radiation therapy. Overall survival and time to progression were calculated. Histopathology of the brain was performed in case of death.

Results

Seven dogs were diagnosed de novo and three had a history of relapsing MUO. Neurological status improved in all 10 dogs during radiation therapy, with 4/10 returning to normal shortly after radiation therapy. Three dogs died within the first three months after radiation therapy. At follow-up MRI lesions completely resolved in two dogs, partially resolved in five dogs, and progressed in one dog. After follow-up MRI, dogs were further treated with prednisolone monotherapy (two dogs) and additional immunosuppressant drugs (five dogs). Overall, four dogs showed disease progression, with a mean time to progression of 691 days (95%CI: 396-987) and mean overall survival for all dogs was 723 days (95%CI: 436-1011) (both medians not reached). Histopathology confirmed MUO in three dogs but was suggestive for oligodendroglioma in one dog. Radiation induced side effects were not seen.

Conclusion

Shortened whole-brain radiation therapy could be an additional treatment option for MUO in conjunction to prednisolone, specifically for cases that require rapid relief of symptoms and with relapsing history.

Ionizing radiation, cerebrovascular disease, and consequent dementia: A review and proposed framework relevant to space radiation exposure

Space exploration requires the characterization and management or mitigation of a variety of human health risks. Exposure to space radiation is one of the main health concerns because it has the potential to increase the risk of cancer, cardiovascular disease, and both acute and late neurodegeneration. Space radiation-induced decrements to the vascular system may impact the risk for cerebrovascular disease and consequent dementia. These risks may be independent or synergistic with direct damage to central nervous system tissues. The purpose of this work is to review epidemiological and experimental data regarding the impact of low-to-moderate dose ionizing radiation on the central nervous system and the cerebrovascular system. A proposed framework outlines how space radiation-induced effects on the vasculature may increase risk for both cerebrovascular dysfunction and neural and cognitive adverse outcomes. The results of this work suggest that there are multiple processes by which ionizing radiation exposure may impact cerebrovascular function including increases in oxidative stress, neuroinflammation, endothelial cell dysfunction, arterial stiffening, atherosclerosis, and cerebral amyloid angiopathy. Cerebrovascular adverse outcomes may also promote neural and cognitive adverse outcomes. However, there are many gaps in both the human and preclinical evidence base regarding the long-term impact of ionizing radiation exposure on brain health due to heterogeneity in both exposures and outcomes. The unique composition of the space radiation environment makes the translation of the evidence base from terrestrial exposures to space exposures difficult. Additional investigation and understanding of the impact of low-to-moderate doses of ionizing radiation including high (H) atomic number (Z) and energy (E) (HZE) ions on the cerebrovascular system is needed. Furthermore, investigation of how decrements in vascular systems may contribute to development of neurodegenerative diseases in independent or synergistic pathways is important for protecting the long-term health of astronauts.

Unleashing the Mystery of a Treated Case of Medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children. Despite advancement in treatment modalities, recurrence remains common, even among those treated with a combination of neurosurgery, craniospinal irradiation, and chemotherapy. The diagnosis of recurrence is usually not difficult in these cases. However, it may pose a challenge in cases with unusual clinical presentation and imaging. Imaging findings on magnetic resonance imaging, with application of perfusion, in conjunction with positron emission tomography-computed tomography can help in clinching the diagnosis in such cases. MB subgroups show consistent patterns even in cases of recurrence, and sonic hedgehog group MB may present as local recurrence showing enhancement with no diffusion restriction, as demonstrated in this case.

Treatment of intracranial neoplasia in dogs using higher doses: A randomized controlled trial comparing a boosted to a conventional radiation protocol

BACKGROUND

Local progression of intracranial tumors can be the consequence of insufficient radiation dose delivered. Dose increases in the brain must be made carefully so as not to risk debilitating adverse effects such as radiation necrosis.

HYPOTHESIS

A new protocol with 10 × 4 Gy + 11% physical dose increase limited to the macroscopic tumor volume results in a clinically better outcome compared to a 10 × 4 Gy protocol.

ANIMALS

Fifty-seven client-owned dogs with primary intracranial neoplasia.

METHODS

Randomized controlled trial. Twenty-eight dogs were assigned to the control protocol (10 × 4 Gy) and 29 to the simultaneous integrated boost (SIB) protocol with 4.45 Gy dose increase. Treatment groups were compared for outcome and signs of toxicity.

RESULTS

Mild, transient acute or early-delayed adverse radiation effects were observed in 5 dogs. Severe late adverse effects were not seen. Between the protocols, no significant differences were found for outcome (intention-to-treat analysis): overall time to progression (TTP) was 708 days (95% confidence interval (95% CI) [545,872]), in the control group it was 828 days (95% CI [401,1256]), and in the SIB group 627 days (95% CI [282,973]; P = .07). Median overall survival (OS) was 684 days (95% CI [516,853]), in the control group it was 724 days (95% CI [623,826]), and in the SIB group 557 days (95% CI [95,1020]; P = .47). None of the tested variables was prognostic in terms of outcome.

CONCLUSION AND CLINICAL IMPORTANCE

The dose escalation used with an 11% physical dose increase did not result in better outcome.

Diffusion tensor imaging in glioblastoma patients treated with volumetric modulated arc radiotherapy: a longitudinal study

BACKGROUND

Chemo- and radiotherapy (RT) is standard treatment for patients with high-grade glioma, but may cause side-effects on the patient's cognitive function.

AIM

Use of diffusion tensor imaging (DTI) to investigate the longitudinal changes in normal-appearing brain tissue in glioblastoma patients undergoing modern arc-based RT with volumetric modulated arc therapy (VMAT) or helical tomotherapy.

MATERIALS AND METHODS

The study included 27 patients newly diagnosed with glioblastoma and planned for VMAT or tomotherapy. All subjects underwent magnetic resonance imaging at the start of RT and at week 3, 6, 15, and 26. Fourteen subjects were additionally imaged at week 52. The DTI data were co-registered to the dose distribution maps. Longitudinal changes in fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) were assessed in the corpus callosum, the centrum semiovale, the hippocampus, and the amygdala.

RESULTS

Significant longitudinal changes in FA, MD, and RD were mainly found in the corpus callosum. In the other examined brain structures, only sparse and transient changes were seen. No consistent correlations were found between biodose, age, or gender and changes in DTI parameters.

CONCLUSION

Longitudinal changes in MD, FA, and RD were observed but only in a limited number of brain structures and the changes were smaller than expected from literature. The results suggest that modern, arc-based RT may have less negative effect on normal-appearing parts of the brain tissue up to 12 months after radiotherapy.

Effect of surgery and radiotherapy on overall survival in patients with chondrosarcoma: A SEER-based study

PURPOSE

Chondrosarcoma is an orthopedic malignancy, and the purpose of this study was to evaluate the effect of surgery and radiotherapy (RT) on the survival of patients with chondrosarcoma.

METHODS

Data were obtained from the SEER database for patients diagnosed with chondrosarcoma between 1988 and 2015. All patients were divided into surgery, RT, surgery + RT, and no surgery/no RT groups. Kaplan-Meier curves were used to analyze the overall survival and cancer-specific survival of patients in different treatment groups. The propensity score matching was used to balance baseline covariates between patients in the surgery and surgery + RT groups and in the RT and surgery + RT groups.

RESULTS

Data from 3756 patients with chondrosarcoma were included in this study. The number of patients who underwent surgery, RT, surgery + RT, and no surgery or RT was 2885 (76.8%), 112 (3.0%), 403 (10.7%), and 356 (9.5%), respectively. Multivariate Cox regression models showed that treatment modality was independent risk factor for OS and CSS. Before PSM, Kaplan-Meier curves showed that OS and CSS were highest in the surgery group and lowest in the RT group. After PSM, although there was no significant difference in OS (p = .13) and CSS (p = .22) between the surgery and surgery + RT group, OS was longer in the surgery group than in the surgery + RT group. Additionally, OS (p < .001) and CSS (p = .009) were longer in the surgery + RT group than in the RT group after PSM.

CONCLUSION

Surgical resection was the key approach for the treatment of chondrosarcoma, while RT confers no significant advantage in improving patient survival time.

Quantifying the risk and dosimetric variables of symptomatic brainstem injury after proton beam radiation in pediatric brain tumors

BACKGROUND

Brainstem toxicity after radiation therapy (RT) is a devastating complication and a particular concern with proton radiation (PBT). We investigated the incidence and clinical correlates of brainstem injury in pediatric brain tumors treated with PBT.

METHODS

All patients <21 years with brain tumors treated with PBT at our institution from 2007-2019, with a brainstem Dmean >30 Gy and/or Dmax >50.4 Gy were included. Symptomatic brainstem injury (SBI) was defined as any new or progressive cranial neuropathy, ataxia, and/or motor weakness with corresponding radiographic abnormality within brainstem.

RESULTS

A total of 595 patients were reviewed and 468 (medulloblastoma = 200, gliomas = 114, ependymoma = 87, ATRT = 43) met our inclusion criteria. Median age at RT was 6.3 years and median prescribed RT dose was 54Gy [RBE]. Fifteen patients (3.2%) developed SBI, at a median of 4 months after RT. Grades 2, 3, 4, and 5 brainstem injuries were seen in 7, 5, 1, and 2 patients respectively. Asymptomatic radiographic changes were seen in 51 patients (10.9%). SBI was significantly higher in patients with age ≤3 years, female gender, ATRT histology, patients receiving high-dose chemotherapy with stem cell rescue, and those not receiving craniospinal irradiation. Patients with SBI had a significantly higher V50-52. In 2014, our institution started using strict brainstem dose constraints (Dmax ≤57 Gy, Dmean ≤52.4 Gy, and V54≤10%). There was a trend towards decrease in SBI from 4.4% (2007-2013) to 1.5% (2014-2019) (P = .089) without affecting survival.

CONCLUSION

Our results suggest a low risk of SBI after PBT for pediatric brain tumors, comparable to photon therapy. A lower risk was seen after adopting strict brainstem dose constraints.

Evaluation of normal-appearing white matter with perfusion and diffusion MRI in patients with treated glioblastoma

OBJECTIVE

We tried to reveal how the normal appearing white matter (NAWM) was affected in patients with glioblastoma treated with chemo-radiotherapy (CRT) in the period following the treatment, by multiparametric MRI.

MATERIALS AND METHODS

43 multiparametric MRI examinations of 17 patients with glioblastoma treated with CRT were examined. A total of six different series or maps were analyzed in the examinations: Apparent Diffusion Coefficient (ADC) and Fractional Anisotropy (FA) maps, Gradient Echo (GRE) sequence, Dynamic susceptibility contrast (DSC) and Arterial spin labeling (ASL) perfusion sequences. Each sequence in each examination was examined in detail with 14 Region of Interest (ROI) measurements. The obtained values were proportioned to the contralateral NAWM values and the results were recorded as normalized values. Time dependent changes of normalized values were statistically analyzed.

RESULTS

The most prominent changes in follow-up imaging occurred in the perilesional region. In perilesional NAWM, we found a decrease in normalized FA (nFA), rCBV (nrCBV), rCBF (nrCBF), ASL (nASL)values (p < 0.005) in the first 3 months after treatment, followed by a plateau and an increase approaching pretreatment values, although it did not reach. Similar but milder findings were present in other NAWM areas. In perilesional NAWM, nrCBV values were found to be positively high correlated with nrCBF and nASL, and negatively high correlated with nADC values (r: 0.963, 0.736, - 0.973, respectively). We also found high correlations between the mean values of nrCBV, nrCBF, nASL in other NAWM areas (r: 0.891, 0.864, respectively).

DISCUSSION

We showed that both DSC and ASL perfusion values decreased correlatively in the first 3 months and showed a plateau after 1 year in patients with glioblastoma treated with CRT, unlike the literature. Although it was not as evident as perfusion MRI, it was observed that the ADC values also showed a plateau pattern following the increase in the first 3 months. Further studies are needed to explain late pathophysiological changes. Because of the high correlation, our results support ASL perfusion instead of contrast enhanced perfusion methods.

Predicted probabilities of brain injury after carbon ion radiotherapy for head and neck and skull base tumors in long-term survivors

BACKGROUND AND PURPOSE

We aimed to determine the risk factors for radiation-induced brain injury (RIBI¹) after carbon ion radiotherapy (CIRT) to predict their probabilities in long-term survivors.

MATERIALS AND METHODS

We evaluated 104 patients with head, neck, and skull base tumors who underwent CIRT in a regimen of 32 fractions and were followed up for at least 24 months. RIBI was assessed using the Common Terminology Criteria for Adverse Events.

RESULTS

The median follow-up period was 45.5 months; 19 (18.3 %) patients developed grade ≥2 RIBI. The maximal absolute dose covering 5 mL of the brain (D5ml) was the only significant risk factor for grade ≥2 RIBI in the multivariate logistic regression analysis (p = 0.001). The tolerance doses of D5ml for the 5% and 50% probabilities of developing grade ≥2 RIBI were estimated to be 55.4 Gy (relative biological effectiveness [RBE]) and 68.4 Gy (RBE) by a logistic model, respectively.

CONCLUSION

D5ml was most significantly associated with grade ≥2 RIBI and may enable the prediction of its probability.

Sensitization of Endothelial Cells to Ionizing Radiation Exacerbates Delayed Radiation Myelopathy in Mice

Delayed radiation myelopathy is a rare, but significant late side effect from radiation therapy that can lead to paralysis. The cellular and molecular mechanisms leading to delayed radiation myelopathy are not completely understood but may be a consequence of damage to oligodendrocyte progenitor cells and vascular endothelial cells. Here, we aimed to determine the contribution of endothelial cell damage to the development of radiation-induced spinal cord injury using a genetically defined mouse model in which endothelial cells are sensitized to radiation due to loss of the tumor suppressor p53. Tie2Cre; p53FL/+ and Tie2Cre; p53FL/- mice, which lack one and both alleles of p53 in endothelial cells, respectively, were treated with focal irradiation that specifically targeted the lumbosacral region of the spinal cord. The development of hindlimb paralysis was followed for up to 18 weeks after either a 26.7 Gy or 28.4 Gy dose of radiation. During 18 weeks of follow-up, 83% and 100% of Tie2Cre; p53FL/- mice developed hindlimb paralysis after 26.7 and 28.4 Gy, respectively. In contrast, during this period only 8% of Tie2Cre; p53FL/+ mice exhibited paralysis after 28.4 Gy. In addition, 8 weeks after 28.4 Gy the irradiated spinal cord from Tie2Cre; p53FL/- mice showed a significantly higher fractional area positive for the neurological injury marker glial fibrillary acidic protein (GFAP) compared with the irradiated spinal cord from Tie2Cre; p53FL/+ mice. Together, our findings show that deletion of p53 in endothelial cells sensitizes mice to the development of delayed radiation myelopathy indicating that endothelial cells are a critical cellular target of radiation that regulates myelopathy.

DCE-MRI detected vascular permeability changes in the rat spinal cord do not explain shorter latency times for paresis after carbon ions relative to photons

BACKGROUND AND PURPOSE

Radiation-induced myelopathy, an irreversible complication occurring after a long symptom-free latency time, is preceded by a fixed sequence of magnetic resonance- (MR-) visible morphological alterations. Vascular degradation is assumed the main reason for radiation-induced myelopathy. We used dynamic contrast-enhanced (DCE-) MRI to identify different vascular changes after photon and carbon ion irradiation, which precede or coincide with morphological changes.

MATERIALS AND METHODS

The cervical spinal cord of rats was irradiated with iso-effective photon or carbon (¹²C-)ion doses. Afterwards, animals underwent frequent DCE-MR imaging until they developed symptomatic radiation-induced myelopathy (paresis II). Measurements were performed at certain time points: 1 month, 2 months, 3 months, 4 months, and 6 months after irradiation, and when animals showed morphological (such as edema/syrinx/contrast agent (CA) accumulation) or neurological alterations (such as, paresis I, and paresis II). DCE-MRI data was analyzed using the extended Toft's model.

RESULTS

Fit quality improved with gradual disintegration of the blood spinal cord barrier (BSCB) towards paresis II. Vascular permeability increased three months after photon irradiation, and rapidly escalated after animals showed MR-visible morphological changes until paresis II. After ¹²C-ion irradiation, vascular permeability increased when animals showed morphological alterations and increased further until animals had paresis II. The volume transfer constant and the plasma volume showed no significant changes.

CONCLUSION

Only after photon irradiation, DCE-MRI provides a temporal advantage in detecting early physiological signs in radiation-induced myelopathy compared to morphological MRI. As a generally lower level of vascular permeability after ¹²C-ions led to an earlier development of paresis as compared to photons, we conclude that other mechanisms dominate the development of paresis II.

Further development of spinal cord retreatment dose estimation: including radiotherapy with protons and light ions

PURPOSE

A graphical user interface (GUI) was developed to aid in the assessment of changes in the radiation tolerance of spinal cord/similar central nervous system tissues with time between two individual treatment courses.

METHODS

The GUI allows any combination of photons, protons (or ions) to be used as the initial, or retreatment, radiotherapy courses. Allowances for clinical circumstances, of reduced tolerance, can also be made. The radiobiological model was published previously and has been incorporated with additional checks and safety features, to be as safe to use as possible. The proton option includes use of a fixed RBE of 1.1 (set as the default), or a variable RBE, the latter depending on the proton linear energy transfer (LET) for organs at risk. This second LET-based approach can also be used for ions, by changing the LET parameters.

RESULTS

GUI screenshots are used to show the input and output parameters for different clinical situations used in worked examples. The results from the GUI are in agreement with manual calculations, but the results are now rapidly available without tedious and error-prone manual computations. The software outputs provide a maximum dose limit boundary, which should not be exceeded. Clinicians may also choose to further lower the number of treatment fractions, whilst using the same dose per fraction (or conversely a lower dose per fraction but with the same number of fractions) in order to achieve the intended clinical benefit as safely as possible.

CONCLUSIONS

The new GUI will allow scientific-based estimations of time related radiation tolerance changes in the spinal cord and similar central nervous tissues (optic chiasm, brainstem), which can be used to guide the choice of retreatment dose fractionation schedules, with either photons, protons or ions.

All for one, though not one for all: team players in normal tissue radiobiology

PURPOSE

As part of the special issue on 'Women in Science', this review offers a perspective on past and ongoing work in the field of normal (non-cancer) tissue radiation biology, highlighting the work of many of the leading contributors to this field of research. We discuss some of the hypotheses that have guided investigations, with a focus on some of the critical organs considered dose-limiting with respect to radiation therapy, and speculate on where the field needs to go in the future.

CONCLUSIONS

The scope of work that makes up normal tissue radiation biology has and continues to play a pivotal role in the radiation sciences, ensuring the most effective application of radiation in imaging and therapy, as well as contributing to radiation protection efforts. However, despite the proven historical value of preclinical findings, recent decades have seen clinical practice move ahead with altered fractionation scheduling based on empirical observations, with little to no (or even negative) supporting scientific data. Given our current appreciation of the complexity of normal tissue radiation responses and their temporal variability, with tissue- and/or organ-specific mechanisms that include intra-, inter- and extracellular messaging, as well as contributions from systemic compartments, such as the immune system, the need to maintain a positive therapeutic ratio has never been more urgent. Importantly, mitigation and treatment strategies, whether for the clinic, emergency use following accidental or deliberate releases, or reducing occupational risk, will likely require multi-targeted approaches that involve both local and systemic intervention. From our personal perspective as five 'Women in Science', we would like to acknowledge and applaud the role that many female scientists have played in this field. We stand on the shoulders of those who have gone before, some of whom are fellow contributors to this special issue.

Brain Damage and Patterns of Neurovascular Disorder after Ionizing Irradiation. Complications in Radiotherapy and Radiation Combined Injury

Exposure to ionizing radiation, mechanical trauma, toxic chemicals or infections, or combinations thereof (i.e., combined injury) can induce organic injury to brain tissues, the structural disarrangement of interactive networks of neurovascular and glial cells, as well as on arrays of the paracrine and systemic destruction. This leads to subsequent decline in cognitive capacity and decompensation of mental health. There is an ongoing need for improvement in mitigating and treating radiation- or combined injury-induced brain injury. Cranial irradiation per se can cause a multifactorial encephalopathy that occurs in a radiation dose- and time-dependent manner due to differences in radiosensitivity among the various constituents of brain parenchyma and vasculature. Of particular concern are the radiosensitivity and inflammation susceptibility of: 1. the neurogenic and oligodendrogenic niches in the subependymal and hippocampal domains; and 2. the microvascular endothelium. Thus, cranial or total-body irradiation can cause a plethora of biochemical and cellular disorders in brain tissues, including: 1. decline in neurogenesis and oligodendrogenesis; 2. impairment of the blood-brain barrier; and 3. ablation of vascular capillary. These changes, along with cerebrovascular inflammation, underlie different stages of encephalopathy, from the early protracted stage to the late delayed stage. It is evident that ionizing radiation combined with other traumatic insults such as penetrating wound, burn, blast, systemic infection and chemotherapy, among others, can exacerbate the radiation sequelae (and vice versa) with increasing severity of neurogenic and microvascular patterns of radiation brain damage.

Efficacy and safety of hypofractionated stereotactic radiotherapy for brain metastases using three fractions: A single-centre retrospective study

PURPOSE

Hypofractionated stereotactic radiotherapy (HFSRT) has become a standard of care for patients with a limited number of brain metastases (BM). An increasing number of linear accelerators (LA) are able to accurately perform HFSRT including VersaHD® (Elekta®) LA. The main aim of this study was to report clinical outcomes of BM treated by HFSRT using 3×7.7Gy on 70% isodose line in terms of local control (LC).

PATIENTS AND METHODS

Between November 2016 and October 2018, all patients suffering from histologically-proven primary with one or several newly diagnosed BM treated by HFSRT were retrospectively included and evaluated. Patients who had received prior treatment by neurosurgery or cerebral radiotherapy were excluded.

RESULTS

Among 44 patients, 61 BM were treated. With a median follow-up of 31.9 months, LC rates at 6 and 12 months were 93.2% and 90.9, respectively. Single-BM was independently predictive of LC (P=0.025) and overall survival (P=0.013). Acute toxicity rates were acceptable: 65.9% of patients had grade 1 and 2 and no acute grade 3 toxicity according to the NCI-CTCAE (version 5.0). Regarding delayed toxicity, one case (2.3%) of radionecrosis was confirmed by magnetic resonance spectroscopy.

CONCLUSION

In our single-centre retrospective analysis, BM treatment by HFSRT delivered in three fractions showed a 12-month LC rate of 90.9% without major toxicities, which suggests safety and efficiency of this technique. However, longer-term follow-up and prospective studies are still needed to confirm these results.

Increased Radiosurgery Toxicity Associated With Treatment of Vestibular Schwannoma in Multiple Sclerosis

OBJECTIVE

Explore the risk of radiation-induced neurotoxicity in patients with multiple sclerosis (MS) treated with stereotactic radiosurgery (SRS) and better understand the pathophysiology of radiation-induced injury in the central nervous system (CNS).

PATIENTS/INTERVENTION

We present the clinical course and magnetic resonance imaging (MRI) findings of a 52-year-old woman with a history of relapsing remitting MS, who developed radiation-induced neurotoxicity following CyberKnife SRS (25 Gy in five fractions) for a left-sided vestibular schwannoma (VS).

MAIN OUTCOME MEASURE

Risk of radiation-induced damage following SRS to the CNS, including radiation type and dose, toxicity, and time to symptom onset, in patients with MS.

RESULTS

Our patient developed increased imbalance (grade 2 toxicity) 3 months following CyberKnife SRS. Brain MRI showed new fluid-attenuated inversion recovery (FLAIR) hyperintensity in the pons and cerebellum. Neurotoxicity from SRS is rare. However, our literature review showed that 19 patients with MS who underwent intracranial radiation therapy sustained radiation-induced toxicity. The potential mechanisms for increased toxicity in MS could be due to a combination of demyelination, inflammatory, and/or vascular changes. Efficacy of treatments including steroids, bevacizumab, and hyperbaric oxygen therapy is currently unknown.

CONCLUSION

Treatment options of SRS and surgery for VS should be carefully considered as patients with known MS may be at increased risk for radiation-induced damage following SRS to the CNS. Thoughtful radiosurgical planning and dosing accounting for this inherent risk is essential for managing patients with MS and VS.

Longitudinal MRI study after carbon ion and photon irradiation: shorter latency time for myelopathy is not associated with differential morphological changes

BACKGROUND

Radiation-induced myelopathy is a severe and irreversible complication that occurs after a long symptom-free latency time if the spinal cord was exposed to a significant irradiation dose during tumor treatment. As carbon ions are increasingly investigated for tumor treatment in clinical trials, their effect on normal tissue needs further investigation to assure safety of patient treatments. Magnetic resonance imaging (MRI)-visible morphological alterations could serve as predictive markers for medicinal interventions to avoid severe side effects. Thus, MRI-visible morphological alterations in the rat spinal cord after high dose photon and carbon ion irradiation and their latency times were investigated.

METHODS

Rats whose spinal cords were irradiated with iso-effective high photon (n = 8) or carbon ion (n = 8) doses as well as sham-treated control animals (n = 6) underwent frequent MRI measurements until they developed radiation-induced myelopathy (paresis II). MR images were analyzed for morphological alterations and animals were regularly tested for neurological deficits. In addition, histological analysis was performed of animals suffering from paresis II compared to controls.

RESULTS

For both beam modalities, first morphological alterations occurred outside the spinal cord (bone marrow conversion, contrast agent accumulation in the musculature ventral and dorsal to the spinal cord) followed by morphological alterations inside the spinal cord (edema, syrinx, contrast agent accumulation) and eventually neurological alterations (paresis I and II). Latency times were significantly shorter after carbon ions as compared to photon irradiation.

CONCLUSIONS

Irradiation of the rat spinal cord with photon or carbon ion doses that lead to 100% myelopathy induced a comparable fixed sequence of MRI-visible morphological alterations and neurological distortions. However, at least in the animal model used in this study, the observed MRI-visible morphological alterations in the spinal cord are not suited as predictive markers to identify animals that will develop myelopathy as the time between MRI-visible alterations and the occurrence of myelopathy is too short to intervene with protective or mitigative drugs.

[Surgical management of brain metastases following female reproductive system cancers: analysis of 37 cases]

Background. Previously, treatment of women with brain metastases following reproductive system cancers was palliative and included whole brain radiotherapy. Currently, treatment approaches have changed and life expectancy has increased. Nevertheless, the role of surgical treatment in these patients is still discussed.

OBJECTIVE

To demonstrate an appropriateness and role of neurosurgical care in the complex management of women with brain metastases following reproductive system cancers.

MATERIAL AND METHODS

There were 78 women with brain metastases following reproductive system cancer. All patients were treated at the Blokhin National Cancer Medical Research Center for the period 2004-2019. We have also reviewed the literature data for the last 30 years.

Results and discussion. Resection of brain metastases in complex treatment of endometrial, ovarian and cervical cancer ensured favorable long-term survival in our material. Thus, mean life expectancy after resection of brain metastases was 16.3 months in patients with ovarian cancer, uterine cancer - 15.6 months, cervical cancer - 10.25 months. Obviously, surgery is not indicated in all cases. However, this approach improves local control and should be used in combination with other treatment methods for improvement of life expectancy and its quality in certain patients.

CONCLUSION

Selective surgical approach should be essential in the treatment of patients with brain metastases following reproductive system cancer. A multidisciplinary approach ensures the best treatment outcomes.

Brain Metastases from Uterine Cervical and Endometrial Cancer

Simple Summary

This review investigated the prevalence, clinical characteristics, clinical presentation, diagnosis, treatment, and prognosis of patients with brain metastases from uterine cervical carcinoma (CC) and uterine endometrial carcinoma (EC). The findings of this review indicate the factors that can facilitate better treatment selection and, consequently, better outcomes in patients with CC and EC.

Abstract

Reports on brain metastases (BMs) from uterine cervical carcinoma (CC) and uterine endometrial carcinoma (EC) have recently increased due to the development of massive databases and improvements in diagnostic procedures. This review separately investigates the prevalence, clinical characteristics, clinical presentation, diagnosis, treatment, and prognosis of BMs from CC and uterine endometrial carcinoma EC. For patients with CC, early-stage disease and poorly differentiated carcinoma lead to BMs, and elderly age, poor performance status, and multiple BMs are listed as poor prognostic factors. Advanced-stage disease and high-grade carcinoma are high-risk factors for BMs from EC, and multiple metastases and extracranial metastases, or unimodal therapies, are possibly factors indicating poor prognosis. There is no “most effective” therapy that has gained consensus for the treatment of BMs. Treatment decisions are based on clinical status, number of the metastases, tumor size, and metastases at distant organs. Surgical resection followed by adjuvant radiotherapy appears to be the best treatment approach to date. Stereotactic ablative radiation therapy has been increasingly associated with good outcomes in preserving cognitive functions. Despite treatment, patients died within 1 year after the BM diagnosis. BMs from uterine cancer remain quite rare, and the current evidence is limited; thus, further studies are needed.

[Radiotherapy and spinal toxicity: News and perspectives]

Radiation-induced myelopathy is a devastating late effect of radiotherapy. Fortunately, this late effect is exceptional. The clinical presentation of radiation myelopathy is aspecific, typically occurring between 6 to 24 months after radiotherapy, and radiation-induced myelopathy remains a diagnosis of exclusion. Magnetic resonance imaging is the most commonly used imaging tool. Radiation oncologists must be extremely cautious to the spinal cord dose, particularly in stereotactic radiotherapy and reirradiation. Conventionally, a maximum dose of 50Gy is tolerated in normofractionated radiotherapy (1.8 to 2Gy per fraction). Repeat radiotherapies lead to consider cumulative doses above this recommendation to offer individualized reirradiation. Several factors increase the risk of radiation-induced myelopathy, such as concomitant or neurotoxic chemotherapy. The development of predictive algorithms to prevent the risk of radiation-induced myelopathy is promising. However, radiotherapy prescription should be cautious, regarding to ALARA principle (as low as reasonably achievable). As the advent of immunotherapy has improved patient survival data and the concept of oligometastatic cancer is increasing in daily practice, stereotactic treatments and reirradiations will be increasingly frequent indications. Predict the risk of radiation-induced myelopathy is therefore a major issue in the following years, and remains a daily challenge for radiation oncologists.

Noninvasive Brain Stimulation & Space Exploration: Opportunities and Challenges

As NASA prepares for longer space missions aiming for the Moon and Mars, astronauts' health and performance are becoming a central concern due to the threats associated with galactic cosmic radiation, unnatural gravity fields, and life in extreme environments. In space, the human brain undergoes functional and structural changes related to fluid shift and changes in intracranial pressure. Behavioral abnormalities, such as cognitive deficits, sleep disruption, and visuomotor difficulties, as well as psychological effects, are also an issue. We discuss opportunities and challenges of noninvasive brain stimulation (NiBS) methods - including transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES) - to support space exploration in several ways. NiBS includes safe and portable techniques already applied in a wide range of cognitive and motor domains, as well as therapeutically. NiBS could be used to enhance in-flight performance, supporting astronauts during pre-flight Earth-based training, as well as to identify biomarkers of post-flight brain changes for optimization of rehabilitation/compensatory strategies. We review these NiBS techniques and their effects on brain physiology, psychology, and cognition.

Liquid Biopsy Strategies to Distinguish Progression from Pseudoprogression and Radiation Necrosis in Glioblastomas

Liquid biopsy for the detection and monitoring of central nervous system tumors is of significant clinical interest. At initial diagnosis, the majority of patients with central nervous system tumors undergo magnetic resonance imaging (MRI), followed by invasive brain biopsy to determine the molecular diagnosis of the WHO 2016 classification paradigm. Despite the importance of MRI for long-term treatment monitoring, in the majority of patients who receive chemoradiation therapy for glioblastoma, it can be challenging to distinguish between radiation treatment effects including pseudoprogression, radiation necrosis, and recurrent/progressive disease based on imaging alone. Tissue biopsy-based monitoring is high risk and not always feasible. However, distinguishing these entities is of critical importance for the management of patients and can significantly affect survival. Liquid biopsy strategies including circulating tumor cells, circulating free DNA, and extracellular vesicles have the potential to afford significant useful molecular information at both the stage of diagnosis and monitoring for these tumors. Here, current liquid biopsy-based approaches in the context of tumor monitoring to differentiate progressive disease from pseudoprogression and radiation necrosis are reviewed.

Low serum 25-hydroxyvitamin D3 levels and late delayed radiation-induced brain injury in patients with nasopharyngeal carcinoma: A case-control study

BACKGROUND AND PURPOSE

Inflammatory reaction plays a critical role in the pathogenesis of late delayed radiation-induced brain injury (RBI). Low vitamin D levels are closely associated with various immuno-inflammatory diseases, but the relationship with late delayed RBI remains unknown. Here, we aimed to determine the association of serum vitamin D levels with clinical parameters in late delayed RBI patients with nasopharyngeal carcinoma.

METHODS

25-Hydroxyvitamin D3 levels and clinical and cerebrospinal fluid parameters were evaluated in 21 patients with RBI and compared with 90 age-, sex-, and season-matched healthy controls.

RESULTS

25-(OH)D3 levels were lower in patients with RBI compared to controls (40.39 ± 22.11 vs. 64.54 ± 19.89 nmol/L, p < .001), especially for aged ≥60 years (vs. <60 years, p = .038), females (vs. males, p = .012), short latency (<5 years) (vs. ≥5 years, p = .015), and severe impairment (LENT/SOMA score ≥3) (vs. LENT/SOMA score <3, p = .010). Serum 25-(OH)D3 levels were associated with age (r = -.464, p = .015), Latency of RBI (r = .416, p = .031) and LENT/SOMA Scale (r = -.488, p = .010).

CONCLUSIONS

Our data showed that serum 25-(OH)D3 levels were reduced in late delayed RBI patients with nasopharyngeal carcinoma.

Malignant giant cell tumor of bone or soft tissue treated by surgery with or without radiotherapy

Malignant giant cell tumor of bone or soft tissue (MGCTBS) is one of the malignant tumors associated with poor prognosis. However, it remains controversial whether the combined treatment of both surgery and radiotherapy (surgery + RT) leads to better survival outcomes than surgical treatment alone (surgery alone) does for patients diagnosed with MGCTBS. We compared the two treatment strategies using the data provided by Surveillance, Epidemiology, and End Results (SEER) program. About 357 patients with MGCTBS who received either surgery + RT or surgery alone between 1975 and 2016 in the USA were identified and then matched based on their propensity scores estimated using the patients' baseline characteristics. We also performed a subgroup analysis for patients with high-grade and regional/distant tumor extension. Unadjusted Kaplan-Meier curves suggested that the surgery alone group had a better 10-year survival profile than the surgery + RT group. After propensity score matching, there was no statistical difference between the two treatment groups with respect to the 10-year cancer-specific survival and overall survival distributions. A subsequent subgroup analysis demonstrated that the surgery alone group has a similar 10-year survival comparing with the surgery + RT group for patients with high-grade and regional/distant tumor extension. The results of our study suggest that RT should not be recommended as a regular therapeutic method for MGCTBS, even for patients with high-grade histology and distant metastasis Clinical Significance: This study may provide better decision making for surgeons dealing with malignant giant cell tumor of bone or soft tissue. Type of study: Observation study. Level of evidence: Level III.

Single- and Multifraction Stereotactic Radiosurgery Dose/Volume Tolerances of the Brain

PURPOSE

As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy investigating normal tissue complication probability (NTCP) after hypofractionated radiation therapy, data from published reports (PubMed indexed 1995-2018) were pooled to identify dosimetric and clinical predictors of radiation-induced brain toxicity after single-fraction stereotactic radiosurgery (SRS) or fractionated stereotactic radiosurgery (fSRS).

METHODS AND MATERIALS

Eligible studies provided NTCPs for the endpoints of radionecrosis, edema, or symptoms after cranial SRS/fSRS and quantitative dose-volume metrics. Studies of patients with only glioma, meningioma, vestibular schwannoma, or brainstem targets were excluded. The data summary and analyses focused on arteriovenous malformations (AVM) and brain metastases.

RESULTS

Data from 51 reports are summarized. There was wide variability in reported rates of radionecrosis. Available data for SRS/fSRS for brain metastases were more amenable to NTCP modeling than AVM data. In the setting of brain metastases, SRS/fSRS-associated radionecrosis can be difficult to differentiate from tumor progression. For single-fraction SRS to brain metastases, tissue volumes (including target volumes) receiving 12 Gy (V12) of 5 cm³, 10 cm³, or >15 cm³ were associated with risks of symptomatic radionecrosis of approximately 10%, 15%, and 20%, respectively. SRS for AVM was associated with modestly lower rates of symptomatic radionecrosis for equivalent V12. For brain metastases, brain plus target volume V20 (3-fractions) or V24 (5-fractions) <20 cm³ was associated with <10% risk of any necrosis or edema, and <4% risk of radionecrosis requiring resection.

CONCLUSIONS

The risk of radionecrosis after SRS and fSRS can be modeled as a function of dose and volume treated. The use of fSRS appears to reduce risks of radionecrosis for larger treatment volumes relative to SRS. More standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses that can refine predictive models of brain toxicity risks.

A Comparison of Ramipril and Bevacizumab to Mitigate Radiation-Induced Brain Necrosis: An Experimental Study

BACKGROUND

Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, is a new treatment approach for radionecrosis. In our study, we compared the prophylactic and therapeutic usage of a promising agent, ramipril (an angiotensin-converting enzyme inhibitor), with that of bevacizumab for reducing radiation-induced brain injury after high-dose stereotactic radiosurgery (SRS).

METHODS

A total of 60 Wistar rats were used. The rats were irradiated with a single dose of 50 Gy using a Leksell Gamma Knife device. Bevacizumab and ramipril were administered in the prophylactic protocol (starting the first day of SRS) and in the therapeutic protocol (starting the fourth week of SRS). Their usage was continued until 12 weeks, and the right frontal lobes of the rats were examined histologically (hematoxylin and eosin stain) and immunohistochemically (hypoxia-inducible factor [HIF]-1α, VEGF, and CD31 antibody expression).

RESULTS

The expression of VEGF, HIF-1α, and CD31 had significantly increased at 12 weeks after SRS compared with the control group. The addition of bevacizumab or ramipril to SRS significantly mitigated the histological severity of radiation injury and the expression of VEGF, HIF-1α, and CD31. However, the prophylactic use of bevacizumab and ramipril seemed to be more effective than therapeutic administration. Our results also revealed that the greatest benefit was achieved with the use of prophylactic administration of bevacizumab compared with other treatment protocols.

CONCLUSIONS

Ramipril might be a promising agent for patients with radionecrosis. Clinical studies are required to investigate the effective and safe doses of ramipril, which is an inexpensive, well-tolerated drug that can cross the blood-brain barrier.

Advanced multimodal imaging in differentiating glioma recurrence from post-radiotherapy changes

Gliomas are the most common malignant primary brain tumor, and their prognosis is extremely poor. Radiotherapy is an important treatment for glioma patients, but the changes caused by radiotherapy have brought difficulties in clinical image evaluation because differentiating glioma recurrence from post-radiotherapy changes including pseudo-progression (PD) and radiation necrosis (RN) remains a challenge. Therefore, accurate and reliable imaging evaluation is very important for making clinical decisions. In recent years, advanced multimodal imaging techniques have been applied to achieve the goal of better differentiating glioma recurrence from post-radiotherapy changes for minimizing errors associated with interpretation of treatment effects. In this review, we discuss the recent applications of advanced multimodal imaging such as diffusion MRI sequences, amide proton transfer MRI sequences, perfusion MRI sequences, MR spectroscopy and multinuclides PET/CT in the evaluation of post-radiotherapy treatment response in glioma patients and highlight their potential role in differentiating post-radiotherapy changes from glioma recurrence.

Efficacy of frameless stereotactic radiotherapy for the treatment of presumptive canine intracranial gliomas: A retrospective analysis (2014-2017)

The use of conventional multi-fractionated radiotherapy for the treatment of glial tumours is well documented in the literature. Recently, stereotactic radiotherapy (SRT) has become more widely available allowing for hypo-fractionated protocols; however, its usefulness in the treatment of canine intracranial gliomas is largely undetermined. We conducted a retrospective analysis, including 21 dogs diagnosed with presumptive intracranial gliomas treated with one or more courses of three fractions of 8 to 10 Gy CyberKnife SRT. The objective of this study was to evaluate the efficacy, safety and prognostic factors associated with the use of SRT for the treatment of canine intracranial gliomas. Overall MST for all dogs was 636 days (d). Dogs treated with one course of the described SRT protocol had a MST of 258 days while those treated with >1 course had a MST of 865 days (P = .0077 log rank, 0.0139 Wilcoxon). Dogs treated with one course of SRT who received adjuvant chemotherapy had a MST of >658 days and lived significantly longer than those who did not receive chemotherapy (MST, 230 days) (P = .0414 log rank, 0.0453 Wilcoxon). The most common adverse event included presumptive transient demyelination in 3/21 dogs, which was treated successfully with corticosteroids in all patients. This study provides evidence that SRT is effective in prolonging survival in dogs with intracranial gliomas, and may provide similar results to conventional fractionated protocols, while decreasing the number of hospital visits and anaesthetic episodes. Additionally, it appears that patients can be safely treated with multiple rounds of SRT resulting in improved survival times.

Radiation Necrosis in Intracranial Lesions

Radiation necrosis (RN) is a challenging potential complication of cranial radiation therapy. Believed to result from a complex interplay of vascular, glial, and immunologic factors, the exact mechanism of RN remains unclear. Patients who develop RN typically have a history of treatment with stereotactic radiation surgery or some other form of radiation-based therapy. The time frame for its development is variable, but it most often occurs one to three years following radiation therapy. Reported treatment doses capable of inducing radiation necrosis are variable, with higher doses per fraction more likely to induce RN. Furthermore, RN remains a challenging diagnosis for clinicians to make, as its presentation is often nonspecific and imaging studies might not clearly differentiate RN from tumor recurrence or pseudoprogression. RN is initially managed with corticosteroids, followed by bevacizumab, surgical resection, or laser interstitial thermal therapy if symptoms persist. In this review, we examine the literature regarding pathophysiology, incidence, imaging characteristics, and management strategies for radiation necrosis.

Neurosurgery and Manned Spaceflight

There has been a renewed interest in manned spaceflight due to endeavors by private and government agencies. Publicized goals include manned trips to or colonization of Mars. These missions will likely be of long duration, exceeding existing records for human exposure to extra-terrestrial conditions. Participants will be exposed to microgravity, temperature extremes, and radiation, all of which may adversely affect their physiology. Moreover, pathological mechanisms may differ from those of a terrestrial nature. Known central nervous system (CNS) changes occurring in space include rises in intracranial pressure and spinal unloading. Intracranial pressure increases are thought to occur due to cephalad re-distribution of body fluids secondary to microgravity exposure. Spinal unloading in microgravity results in potential degenerative changes to the bony vertebrae, intervertebral discs, and supportive musculature. These phenomena are poorly understood. Trauma is of highest concern due to its potential to seriously incapacitate crewmembers and compromise missions. Traumatic pathology may also be exacerbated in the setting of altered CNS physiology. Though there are no documented instances of CNS pathologies arising in space, existing diagnostic and treatment capabilities will be limited relative to those on Earth. In instances where neurosurgical intervention is required in space, it is not known whether open or endoscopic approaches are feasible. It is obvious that prevention of trauma and CNS pathology should be emphasized. Further research into neurosurgical pathology, its diagnosis, and treatment in space are required should exploratory or colonization missions be attempted.

Radiation Induced Demyelination in Cervical Spinal Cord of the Head and Neck Cancer Patients after Receiving Radiotherapy

Background:

Cervical spinal cord is important and radiosensitive. It is the most critical organ for the head and neck (H&N) cancer patients during radiotherapy. If the delivered dose to the cord is more than tolerance dose, demyelination may occur.

Objective:

Current study aims to analyze the post radiotherapy status of cord in the H&N cancer patients

Material and Methods:

In this analytical study, sixty patients who received more than 50 Gray (Gy) dose for more than 10 cm length of spinal cord participated in the study. All the patients were clinically examined and magnetic resonance imaging (MRI) was performed for patients who had demyelination symptoms. Adequate medical management was provided for all the patients having demyelination.

Results:

Out of sixty patients, ten cases were reported with demyelination symptoms, and only six cases gave consent for this study. One patient was found to have irreversible demyelination while five patients had reversible demyelination.

Conclusion:

Demyelination may occur if long segment spinal cord receives dose more than tolerance limit. However target dose should not be compromised up to 54 Gy to spinal cord.

Revisiting the Role of Radiation Therapy in Chondrosarcoma: A National Cancer Database Study

Background

Although chondrosarcomas (CS) are mostly considered radioresistant, advancements in radiotherapy have brought attention to its use in these patients. Using the largest registry of primary bone tumors, the National Cancer Database (NCDB), we sought to better characterize the current use of radiotherapy in CS patients and identify any potential survival benefit with higher radiation doses and advanced radiation therapies.

Methods

We retrospectively analyzed CS patients in the NCDB from 2004 to 2015 who underwent radiotherapy. The Kaplan–Meier method with statistical comparisons was used to identify which individual variables related to dosage and delivery modality were associated with improved 5-year survival rates. Multivariate proportional hazards analyses were performed to determine independent predictors of survival.

Results

Of 5,427 patients with a histologic diagnosis of chondrosarcoma, 680 received a form of radiation therapy (13%). The multivariate proportional hazards analysis controlling for various patient, tumor, and treatment variables, including RT dose and modality, demonstrated that while overall radiation therapy (RT) was not associated with improved survival (HR 0.96, 95% CI 0.76–1.20), when examining just the patient cohort with positive surgical margins, RT trended towards improved survival (HR 0.81, 95% CI 0.58–1.13). When comparing advanced and conventional RT modalities, advanced RT was associated with significantly decreased mortality (HR 0.55, 95% CI 0.38–0.80). However, advanced modality and high-dose RT both trended only toward improved survival compared to patients who did not receive any RT (HR 0.74, 95% CI 0.52–1.06 and HR 0.93, 95% CI 0.71–1.21, respectively).

Conclusions

Despite the suggested radioresistance of CS, modern radiotherapies may present a treatment option for certain patients. Our results support a role for high-dose, advanced radiation therapies in selected high-risk CS patients with tumors in surgically challenging locations or unplanned positive margins. While there is an associated survival rate benefit, further, prospective studies are needed for validation.