Radiobiology and radiotherapy of brain metastases

Thiagarajan, Anuradha; Yamada, Yoshiya

doi:10.1007/s10585-017-9865-7

Cited by 25 publications

(16 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As current radiobiologic understanding suggests that brain metastases have a very high α/β ratio of around 12, whereas surrounding normal brain tissue is characterized by a low α/β of 2-3, dose fractionation should—in theory—be able to optimize local control while avoiding increased risk for radionecrosis ( 8 – 10 ). On the other hand, large single doses in excess of 8 Gy have been shown to cause endothelial cell apoptosis via the acid sphingomyelinase pathway, which has been discussed to enhance the effect of SRS in comparison to fractionated treatment ( 11 , 12 ). However, while SRS has been the first and foremost modality investigated in prospective studies, evidence on FSRT is still scarce and especially comparative analyses between FSRT and SRS are mostly lacking ( 13 ).…”

Section: Introductionmentioning

confidence: 99%

FSRT vs. SRS in Brain Metastases—Differences in Local Control and Radiation Necrosis—A Volumetric Study

et al. 2020

View full text Add to dashboard Cite

Background: While the role of stereotactic radiotherapy for brain metastases is increasing, evidence on the comparative efficacy and safety of fractionated stereotactic radiotherapy (FSRT) and single-session radiosurgery (SRS) is scarce. Methods: Longitudinal volumetric analysis was performed in a consecutive cohort of 120 patients and 190 brain metastases (>0.065 cm 3 in volume / > ∼5 mm in diameter) treated exclusively with FSRT (n = 98) and SRS (n = 92), respectively. A total of 972 tumor segmentations was used, averaging 5.1 time points per metastasis. Progression was defined using a volumetric extension of the RANO-BM criteria. Local control and radionecrosis were compared for lesions treated with FSRT and SRS, respectively. Results: Metastases treated with FSRT were significantly larger at baseline (mean, 4.66 vs. 0.40 cm 3 , p < 0.001). Biologically effective dose (BED) for metastases (α/β = 12, linear-quadratic-cubic model) was significantly associated with local control, whereas BED for normal brain (α/β = 2, linear-quadratic model) was significantly associated with radionecrosis. Median time to local progression was 22.9 months in the FSRT group compared to 14.5 months in the SRS group (p = 0.022). Overall radionecrosis rate at 12 months was 3.4% for FSRT and 14.8% for SRS (p = 0.010). Radionecrosis • IV requiring resection with histologic proof of radiation necrosis also was significantly reduced in the FSRT group (FSRT 0.0% vs. SRS 3.9%, p = 0.041). In multivariate analysis, FSRT was associated with reduced risk of progression (HR 0.47, p = 0.015) and reduced risk of radionecrosis (HR 0.18, p = 0.045). Conclusions: This volumetric study provides initial evidence that the improvements in therapeutic ratio expected for FSRT in larger brain metastases, might equally extend into the domain of smaller metastases, traditionally less considered for fractionated treatment. FSRT might constitute an important tool to further increase local control and reduce radionecrosis risk in stereotactic radiotherapy for brain metastases, that should be assessed in randomized intervention trials.

show abstract

Section: Introductionmentioning

confidence: 99%

FSRT vs. SRS in Brain Metastases—Differences in Local Control and Radiation Necrosis—A Volumetric Study

et al. 2020

View full text Add to dashboard Cite

show abstract

“…30 The eight lesions with tumor size reduction at time point III all showed a further increase in TSC at time point II shortly after SRS followed by a significant decrease at time point III below the initial TSC values. Considering the two different main types of radiation-induced cell death, apoptosis and mitotic cell death or mitotic catastrophe, 28,31,32 the short-term TSC increase can be predicated to the induced endothelial-cell apoptosis followed by autophagy. Apoptosis amount for the majority of ionizing radiation induced cell death characterized by cell shrinkage and increased cell membrane permeability.…”

Section: Discussionmentioning

confidence: 99%

MRI Detection of Changes in Tissue Sodium Concentration in Brain Metastases after Stereotactic Radiosurgery: A Feasibility Study

Mohamed

Adlung

Ruder

et al. 2020

Journal of Neuroimaging

View full text Add to dashboard Cite

BACKGROUND AND PURPOSE: To date, treatment response to stereotactic radiosurgery (SRS) in brain metastases (BM) can only be determined by MRI evaluation of contrast-enhancing lesions in a long-time follow-up. Sodium MRI has been a subject of immense interest in imaging research as the measure of tissue sodium concentration (TSC) can give valuable quantitative information on cell viability. We aimed to analyze the longitudinal changes of TSC in BM measured with 23 Na MRI before and after SRS for assessment of early local tumor effects. METHODS: Seven patients with a total of 12 previously untreated BM underwent SRS with 22 Gy. In addition to a standard MRI protocol including dynamic susceptibility-weighted contrast-enhanced perfusion, a 23 Na MRI was performed at three time points: (I) 2 days before, (II) 5 days, and (III) 40 days after SRS. Nine BMs were evaluated. The absolute TSC in the BM, the respective peritumoral edemas, and the normal-appearing corresponding contralateral brain area were assessed and the relative TSC were correlated to the changes in BM longest axial diameters. RESULTS: TSC was elevated in nine BM at baseline before SRS with a mean of 73.4 ± 12.3 mM. A further increase in TSC was observed 5 days after SRS in all the nine BM with a mean of 86.9 ± 13 mM. Eight of nine BM showed a mean 60.6 ± 13.3% decrease in the longest axial diameter 40 days after SRS; at this time point, the TSC also had decreased to a mean 65.1 ± 7.9 mM. In contrast, one of the nine BM had a 13.4% increase in the largest axial diameter at time point III. The TSC of this BM showed a further TSC increase of 80.1 mM 40 days after SRS. CONCLUSION: Changes in TSC using 23 Na MRI shows the possible capability to detect radiobiological changes in BM after SRS.

show abstract

“…IR, absorbed by tissues and cells, affects their functioning and structure to various extents, depending on the dose and type of radiation [13,14]. In affected cells, ROS are generated mainly through the radiolysis of water molecules (decay by the action of radiation quanta) or the excitation of water molecules and their decay [15,16,39].…”

Section: Ionizing Radiation As a Source Of Reactive Oxygen Speciesmentioning

confidence: 99%

“…The mechanism of deleterious IR action is strongly associated with increasing oxidative stress in irradiated tissues [12]. IR is capable of penetrating the cells of living organisms, where it induces the ionization of both organic and inorganic compounds [13,14]. Due to the high water content in cells, radiolysis of water molecules by IR is the main process contributing to the increased formation of reactive oxygen species (ROS) [15,16].…”

Section: Introductionmentioning

confidence: 99%

Ionizing Radiation as a Source of Oxidative Stress—The Protective Role of Melatonin and Vitamin D

Nuszkiewicz

Woźniak

Szewczyk-Golec

2020

IJMS

View full text Add to dashboard Cite

Ionizing radiation (IR) has found widespread application in modern medicine, including medical imaging and radiotherapy. As a result, both patients and healthcare professionals are exposed to various IR doses. To minimize the negative side effects of radiation associated with oxidative imbalance, antioxidant therapy has been considered. In this review, studies on the effects of melatonin and vitamin D on radiation-induced oxidative stress are discussed. According to the research data, both substances meet the conditions for use as agents that protect humans against IR-induced tissue damage. Numerous studies have confirmed that melatonin, a hydro- and lipophilic hormone with strong antioxidant properties, can potentially be used as a radioprotectant in humans. Less is known about the radioprotective effects of vitamin D, but the results to date have been promising. Deficiencies in melatonin and vitamin D are common in modern societies and may contribute to the severity of adverse side effects of medical IR exposure. Hence, supporting supplementation with both substances seems to be of first importance. Interestingly, both melatonin and vitamin D have been found to selectively radiosensitise cancer cells, which makes them promising adjuvants in radiotherapy. More research is needed in this area, especially in humans.

show abstract

Radiobiology and radiotherapy of brain metastases

Cited by 25 publications

References 32 publications

FSRT vs. SRS in Brain Metastases—Differences in Local Control and Radiation Necrosis—A Volumetric Study

FSRT vs. SRS in Brain Metastases—Differences in Local Control and Radiation Necrosis—A Volumetric Study

MRI Detection of Changes in Tissue Sodium Concentration in Brain Metastases after Stereotactic Radiosurgery: A Feasibility Study

Ionizing Radiation as a Source of Oxidative Stress—The Protective Role of Melatonin and Vitamin D

Contact Info

Product

Resources

About