Effects of radiation on bone

New sensor options for smart fracture implants and wearable devices: Laser-Doppler and white-light spectroscopy allow monitoring of bone regeneration via perfusion measurement

The diagnostic options for monitoring fracture healing are currently limited to methods that expose patients to ionizing radiation, i.e. X-rays or computed tomography. The development of new methods that ideally allow continuous monitoring via smart implants or wearables is urgently needed. Laser-Doppler and white-light spectroscopy, non-invasive light-based methods, could allow to monitor fracture healing via changes in perfusion, but this has never been investigated. It was hypothesized that 1) blood flow (BF) increases before a linear increase in oxygen saturation (SO2) and that 2) SO2 in nonunion cases remains as low as the minimum in union cases. A longitudinal observational cohort study with tibial fracture patients was conducted with additional cross-sectional measurements in nonunion patients and healthy controls. To assess SO2, relative haemoglobin amount (rHb), and BF in the fracture gap, the 'Oxygen to see' (O2C) device was used. Thirty-five patients (20 longitudinal, 15 nonunion) and 28 controls were included. In the longitudinal group, SO2 decreased, reaching a minimum (10 mm: 17.96 days, 16 mm: 15.50 days), and subsequently increased. BF increased to a maximum (10 mm: 12.90 days, 16 mm: 33.51 days), followed by a decrease. The SO2 values in the nonunion group were similar to the minimum values in the longitudinal group. Findings in nonunion patients vs. controls differed only in SO2 (10 mm: p < 0.001, 16 mm: p = 0.038), not in rHb or BF. Laser-Doppler and white-light spectroscopy provide characteristic SO2 and BF trajectories that may serve to monitor fracture healing.

FLASH Radiotherapy: From In Vivo Data to Clinical Translation

Delivery of radiotherapy (RT) at ultra-high dose rates or FLASH radiotherapy (FLASH-RT) is an emerging treatment option for patients with cancer that could increase survival outcomes and quality of life. In vivo data across a multitude of normal tissues and associated tumors have been published demonstrating the FLASH effect while bringing attention to the need for additional research. Combination of FLASH-RT with other treatment options including spatially fractionated RT, immunotherapy, and usage in the setting of reirradiation could also provide additional benefit. Phase I clinical trials have shown promising results, yet research is warranted before routine clinical use of FLASH-RT.

The Association between Gene Expression Profiling and Regression Rate of Posterior Uveal Melanoma following Proton Beam Irradiation

Introduction

This study evaluated the association between gene expression profiling (GEP), PRAME (preferentially expressed antigen in melanoma), and regression rate of uveal melanoma after proton beam irradiation (PBI).

Methods

A retrospective review of uveal melanoma patients treated with PBI between 2013 and 2021, with GEP results and at least 3 post-radiation ultrasound measurements, was conducted. Patients with local recurrences were excluded. Regression rates were analyzed using a linear mixed model to predict percentage change in thickness from baseline. Cox regression was conducted to determine whether slow or fast regression, based on the median regression rate at 18 months, correlates with metastasis risk.

Results

The study included 106 patients, with GEP classifications of 1A in 43.4%, 1B in 25.5%, and 2 in 31.1%. Overall, the mean change in tumor thickness was 20.9%, 35.1%, 51.4%, and 59.3% at 1 year, 2 years, 4 years, and 6 years, respectively. No differences in regression rates between GEP classes and PRAME expression were found through 72 months post-PBI. The median regression at 18 months was 27.1%. Slow and fast regression was not associated with the risk of metastasis.

Conclusion

No association between GEP, PRAME, and regression rate was found through 72 months post-PBI.

Bone complications of cancer treatment

With the advancements in conventional treatment modalities such as radiation, chemotherapy, and surgery, as well as the emergence of immunotherapy, the overall cure rate for solid tumor malignancies has experienced a significant increase. However, it is unfortunate that exposure to cancer treatments can have detrimental effects on the function of osteoblasts and osteoclasts, disturbing bone metabolic homeostasis in patients, as well as causing damage to bone marrow cells and other bone tissues. Consequently, certain tumor treatment options may pose a risk for subsequent bone diseases. Common bone disorders associated with cancer treatment include osteonecrosis, bone loss, and secondary bone tumors. (1)Cancer treatment-related osteonecrosis is primarily linked to the use of radiation therapy and certain chemicals, such as bisphosphonates, denosumab, antiangiogenic agents, and immunomodulators. It has been observed that high-dose radiation therapy is more likely to result in osteonecrosis. (2)Chemicals and hormones, particularly sex hormones, glucocorticoids, and thyroid hormones or thyrotropic hormones, are among the factors that can contribute to cancer treatment-related bone loss. (3)Secondary bone tumors differ from metastases originating from primary tumors, and radiotherapy plays a significant role in their development, while chemotherapy may also exert some influence. Radiogenic secondary bone tumors are predominantly malignant, with osteosarcoma being the most common type. Chemotherapy may be a risk factor for the relatively rare occurrence of secondary Ewing sarcoma of the bone. These treatment-related bone disorders have a considerable adverse impact on the prognosis of cancer patients. Hence, it is imperative to prioritize the bone health of patients undergoing cancer treatment and give it further attention.

AOP Report: Development of an adverse outcome pathway for deposition of energy leading to bone loss

Bone loss, commonly seen in osteoporosis, is a condition that entails a progressive decline of bone mineral density and microarchitecture, often seen in post-menopausal women. Bone loss has also been widely reported in astronauts exposed to a plethora of stressors and in patients with osteoporosis following radiotherapy for cancer. Studies on mechanisms are well documented but the causal connectivity of events to bone loss development remains incompletely understood. Herein, the adverse outcome pathway (AOP) framework was used to organize data and develop a qualitative AOP beginning from deposition of energy (the molecular initiating event) to bone loss (the adverse outcome). This qualitative AOP was developed in collaboration with bone loss research experts to aggregate relevant findings, supporting ongoing efforts to understand and mitigate human system risks associated with radiation exposures. A literature review was conducted to compile and evaluate the state of knowledge based on the modified Bradford Hill criteria. Following review of 2029 studies, an empirically supported AOP was developed, showing the progression to bone loss through many factors affecting the activities of bone-forming osteoblasts and bone-resorbing osteoclasts. The structural, functional, and quantitative basis of each proposed relationship was defined, for inference of causal changes between key events. Current knowledge and its gaps relating to dose-, time- and incidence-concordance across the key events were identified, as well as modulating factors that influence linkages. The new priorities for research informed by the AOP highlight areas for improvement to enable development of a quantitative AOP used to support risk assessment strategies for space travel or cancer radiotherapy.

Histograms of computed tomography values in differential diagnosis of benign and malignant osteogenic lesions

BACKGROUND

The use of histogram analysis of computed tomography (CT) values is a potential method for differentiating between benign osteoblastic lesions (BOLs) and malignant osteoblastic lesions (MOLs).

PURPOSE

To explore the diagnostic efficacy of histogram analysis in accurately distinguishing between BOLs and MOLs based on CT values.

MATERIAL AND METHODS

A total of 25 BOLs and 25 MOLs, which were confirmed through pathology or imaging follow-up, were included in this study. FireVoxel software was used to process the lesions and obtain various histogram parameters, including mean value, standard deviation, variance, coefficient of variation, skewness, kurtosis, entropy value, and percentiles ranging from 1st to 99th. Statistical tests, such as two independent-sample t-tests and the Mann-Whitney U test with Bonferroni correction, were employed to compare the differences in histogram parameters between BOLs and MOLs. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficacy of each parameter.

RESULTS

Significant differences were observed in several histogram parameters between BOLs and MOLs, including the mean value, coefficient of variation, skewness, and various percentiles. Notably, the 25th percentile demonstrated the highest diagnostic efficacy, as indicated by the largest area under the curve in the ROC curve analysis.

CONCLUSION

Histogram analysis of CT values provides valuable diagnostic information for accurately differentiating between BOLs and MOLs. Among the different parameters, the 25th percentile parameter proves to be the most effective in this discrimination process.

M2 macrophage-derived exosomes carry miR-142-3p to restore the differentiation balance of irradiated BMMSCs by targeting TGF-β1

Radiotherapy is essential to cancer treatment, while it inevitably injures surrounding normal tissues, and bone tissue is one of the most common sites prone to irradiation. Bone marrow mesenchymal stem cells (BMMSCs) are sensitive to irradiation and the irradiated dysfunction of BMMSCs may be closely related to irradiation-induced bone damage. Macropahges play important role in regulating stem cell function, bone metabolic balance and irradiation response, but the effects of macrophages on irradiated BMMSCs are still unclear. This study aimed to investigate the role of macrophages and macrophage-derived exosomes in restoring irradiated BMMSCs function. The effects of macrophage conditioned medium (CM) and macrophage-derived exosomes on osteogenic and fibrogenic differentiation capacities of irradiated BMMSCs were detected. The key microribonucleic acids (miRNAs) and targeted proteins in exosomes were also determined. The results showed that irradiation significantly inhibited the proliferation of BMMSCs, and caused differentiation imbalance of BMMSCs, with decreased osteogenic differentiation and increased fibrogenic differentiation. M2 macrophage-derived exosomes (M2D-exos) inhibited the fibrogenic differentiation and promoted the osteogenic differentiation of irradiated BMMSCs. We identified that miR-142-3p was significantly overexpressed in M2D-exos and irradiated BMMSCs treated with M2D-exos. After inhibition of miR-142-3p in M2 macrophage, the effects of M2D-exos on irradiated BMMSCs differentiation were eliminated. Furthermore, transforming growth factor beta 1 (TGF-β1), as a direct target of miR-142-3p, was significantly decreased in irradiated BMMSCs treated with M2D-exos. This study indicated that M2D-exos could carry miR-142-3p to restore the differentiation balance of irradiated BMMSCs by targeting TGF-β1. These findings pave a new way for promising and cell-free method to treat irradiation-induced bone damage.

Does Microwave Exposure at Different Doses in the Pre/Postnatal Period Affect Growing Rat Bone Development?

Effects of pre/postnatal 2.45 GHz continuous wave (CW), Wireless-Fidelity (Wi-Fi) Microwave (MW) irradiation on bone have yet to be well defined. The present study used biochemical and histological methods to investigate effects on bone formation and resorption in the serum and the tibia bone tissues of growing rats exposed to MW irradiation during the pre/postnatal period. Six groups were created: one control group and five experimental groups subjected to low-level different electromagnetic fields (EMF) of growing male rats born from pregnant rats. During the experiment, the bodies of all five groups were exposed to 2.45 GHz CW-MW for one hour/day. EMF exposure started after fertilization in the experimental group. When the growing male rats were 45 days old in the postnatal period, the control and five experimental groups' growing male and maternal rats were sacrificed, and their tibia tissues were removed. Maternal rats were not included in the study. No differences were observed between the control and five experimental groups in Receptor Activator Nuclear factor-kB (RANK) biochemical results. In contrast, there was a statistically significant increase in soluble Receptor Activator of Nuclear factor-kB Ligand (sRANKL) and Osteoprotegerin (OPG) for 10 V/m and 15 V/m EMF values. Histologically, changes in the same groups supported biochemical results. These results indicate that pre/postnatal exposure to 2.45 GHz EMF at 10 and 15 V/m potentially affects bone development.

Late Complications in Long-Term Childhood Cancer Survivors: What the Oral Health Professional Needs to Know

With diagnostic and therapeutic advances, over 80% of children diagnosed with cancer become long-term survivors. As the number of childhood cancer survivors (CCS) continues to increase, dental practitioners become more likely to have CCS among their patients. CCS may develop late complications from damage caused by their cancer treatment to endocrine, cardiovascular, musculoskeletal, and other organ systems. These complications may surface decades after the completion of treatment. Adverse outcomes of childhood cancer treatment frequently involve oral and craniofacial structures including the dentition. Tooth development, salivary gland function, craniofacial growth, and temporomandibular joint function may be disturbed, increasing oral health risks in these individuals. Moreover, CCS are at risk of developing subsequent malignancies, which may manifest in or near the oral cavity. It is important that dental practitioners are aware of the childhood cancer history of their patients and have knowledge of potential late complications. Therefore, this narrative review aims to inform dental practitioners of late oral complications of cancer treatment modalities commonly used in pediatric oncology. Furthermore, selected common non-oral late sequelae of cancer therapy that could have an impact on oral health and on delivering dental care will be discussed.

Imaging of the Posttreatment Head and Neck: Expected Findings and Potential Complications

Interpretation of posttreatment imaging findings in patients with head and neck cancer can pose a substantial challenge. Malignancies in this region are often managed through surgery, radiation therapy, chemotherapy, and newer approaches like immunotherapy. After treatment, patients may experience various expected changes, including mucositis, soft-tissue inflammation, laryngeal edema, and salivary gland inflammation. Imaging techniques such as CT, MRI, and PET scans help differentiate these changes from tumor recurrence. Complications such as osteoradionecrosis, chondroradionecrosis, and radiation-induced vasculopathy can arise because of radiation effects. Radiation-induced malignancies may occur in the delayed setting. This review article emphasizes the importance of posttreatment surveillance imaging to ensure proper care of patients with head and neck cancer and highlights the complexities in distinguishing between expected treatment effects and potential complications. Keywords: CT, MR Imaging, Radiation Therapy, Ear/Nose/Throat, Head/Neck, Nervous-Peripheral, Bone Marrow, Calvarium, Carotid Arteries, Jaw, Face, Larynx © RSNA, 2024.

Impact of external beam radiation on total shoulder arthroplasty outcomes: a propensity-matched cohort study

BACKGROUND

External beam radiation therapy has a number of deleterious effects on the body, and a number of post-operative complications have been reported for several surgeries including total knee arthroplasty. However, few studies have investigated the impact of external beam radiation therapy for total shoulder arthroplasty (TSA). Our study aimed to assess the systemic and joint complications associated with TSA in patients with prior radiation exposures, as well as evaluate the surgical outcomes of radiation patients compared to non-radiation TSA patients.

MATERIALS AND METHODS

A retrospective cohort analysis was conducted using the TriNetX Analytics Network. A 1:1 propensity score matching function was utilized to create two cohorts with matched baseline characteristics within the TriNetX network. Comparisons of the primary and secondary outcomes between the two cohorts were made using odds ratios. A p value of < 0.05 was determined to be significant.

RESULTS

A total of 75,510 patients that received TSA were identified with 1505 having a history of radiation therapy (RT) and 73,605 with no radiation therapy (non-RT). After propensity matching, both groups contained 1484 patients. RT patients were at higher risk for developing prosthetic joint infection, acute renal failure, altered mental state, cerebrovascular event, DVT, PE, pneumonia, respiratory failure, and UTI compared to non-RT patients at different time points (p < 0.5).

CONCLUSION

Patients with prior history of external beam radiation undergoing TSA had a higher risk of systemic complications and prosthetic joint infection compared to patients without a prior history. These complications suggest a more complicated post-operative management course for these patients.

Pilot Study: Short Term Impact of Radiation Therapy on Bone Mineral Density and Bone Metabolism

Despite the risk of complications, high dose radiation therapy is increasingly utilized in the management of selected bone malignancies. In this study, we investigate the impact of moderate to high dose radiation (over 50 Gy) on bone metabolism and structure. Between 2015 and 2018, patients with a primary malignant bone tumor of the sacrum that were either treated with high dose definitive radiation only or a combination of moderate to high dose radiation and surgery were prospectively enrolled at a single institution. Quantitative CTs were performed before and after radiation to determine changes in volumetric bone mineral density (BMD) of the irradiated and non-irradiated spine. Bone histomorphometry was performed on biopsies of the irradiated sacrum and the non-irradiated iliac crest of surgical patients using a quadruple tetracycline labeling protocol. In total, 9 patients were enrolled. Two patients received radiation only (median dose 78.3 Gy) and 7 patients received a combination of preoperative radiation (median dose 50.4 Gy), followed by surgery. Volumetric BMD of the non-irradiated lumbar spine did not change significantly after radiation, while the BMD of the irradiated sacrum did (pre-radiation median: 108.0 mg/cm3 (IQR 91.8-167.1); post-radiation median: 75.3 mg/cm3 (IQR 57.1-110.2); p = 0.010). The cancellous bone of the non-irradiated iliac crest had a stable bone formation rate, while the irradiated sacrum showed a significant decrease in bone formation rate [pre-radiation median: 0.005 mm3/mm2/year (IQR 0.003-0.009), post-radiation median: 0.001 mm3/mm2/year (IQR 0.001-0.001); p = 0.043]. Similar effects were seen in the cancellous and endocortical envelopes. This pilot study shows a decrease of volumetric BMD and bone formation rate after high-dose radiation therapy. Further studies with larger cohorts and other endpoints are needed to get more insight into the effect of radiation on bone. Level of evidence: IV.

MakoTM robotic-arm-assisted total hip and total knee arthroplasty outcomes in an orthopedic oncology setting: A case series

Background

The MAKO Robotic-Arm system is a cutting-edge technology which combines both computed tomography (CT) scanning and three-dimensional planning to determine the ideal size and orientation of implants prior to bone resection. It is typically utilized within a general orthopedic setting for joint replacement procedures, such as total joint arthroplasties. However, its use within orthopedic oncology, which contains a much more compromised patient population and more complex surgical treatment, is not well documented within the literature.

Question/purposes

To determine the patient outcomes of those who underwent a total hip arthroplasty (THA) or total knee arthroplasty (TKA) at Morristown Medical Center using the MAKO Robotic-Arm System. Particularly, we aspired to delve into the use of the MAKO in an orthopedic oncology setting for patients with a degenerative hip or knee and a history of cancer or other orthopedic tumor, impending pathological fracture, PVNS, chondromatosis, radiation therapy, or other oncological related conditions.

Patients and methods

Our institution monitored twenty-five individuals with unique orthopedic oncology conditions that underwent MAKO robotic-assisted total hip and knee arthroplasty. This was performed between 2020 and 2022 at Morristown Medical Center in New Jersey. During this time period, 52% (13/25) of the operations were performed on knees and 48% (12/25) were performed on hips. Data regarding patient demographics, body mass index (BMI), medications, hemoglobin, hematocrit, comorbidities, American Society of Anesthesiologists (ASA) Class, operative data, the length of stay (LOS), readmission rates due to infection or periprosthetic fractures, and complications were collected retrospectively. All confidence intervals were calculated at the 95% confidence level.

Results

Postoperatively, the average LOS was 3.2 days, and there were no complications after any of the MAKO-assisted joint arthroplasty procedures. Additionally, there were no readmissions at any of our recorded intervals - 1-30, 1-60, 1-90, and 1 year - however one patient presented to the emergency department after falling 4 days post-operatively. X-ray imaging ultimately revealed no periprosthetic fracture or malalignment of the prosthesis.

Conclusions

The utilization of the MAKO Robotic-Arm System for joint arthroplasty procedures (THAs and TKAs) on orthopedic oncology patients yielded exceptional outcomes, with no complications or readmissions directly attributed to the use of this innovative robotic technology. Thus, this newly emerging surgical system holds great promise, potentially revolutionizing the approach for selected orthopedic oncology patients undergoing total joint arthroplasty compared to the traditional manual techniques. It further demonstrates that its use in an orthopedic oncology setting - where the cohort of patients are often compromised, leading to more intricate surgeries with heightened risks - elicits safety and provides optimal outcomes for patients. Nevertheless, its role within the field is evolving, and in the coming years, as it gains further popularity and sees broader application by orthopedic oncology surgeons, its potential will become clearer. To solidify its position, future clinical investigations and prospective research should be conducted to support the preference of the MAKO system over traditional manual techniques. This will help provide the necessary evidence to advocate for its widespread adoption and continued advancements in orthopedic oncology procedures.

CR6-Interacting Factor-1 Promotes Osteoclastogenesis Through the NF-κB Signaling Pathway after Irradiation

Radiation exposure arising from radiotherapy may induce rapid bone loss and an increase in the extent of bone resorption. Reactive oxygen species (ROS) caused by radiation exposure play a crucial role during the process of osteoclastogenesis. However, the pathological mechanisms underlying radiation-induced osteoclastogenesis have yet to be fully elucidated. CR6-interacting factor-1 (Crif1) as a multifunctional protein is involved in regulating multiple biological functions in cells. Here, we investigated the role of Crif1 in radiation-induced osteoclastogenesis and found that radiation exposure induced an increase in the expression level of Crif1 and enhanced osteoclastogenesis in osteoclast progenitors. Crif1 and NF-κB p65 co-localized in the cytoplasm after radiation exposure. Crif1 knockdown did not affect the phosphorylation and total protein levels of extracellular signal-regulated kinases (ERK), c-Jun amino (N)-terminal kinases (JNK), p38, and IκB-α before and after irradiation. However, Crif1 knockdown did lead to the reduced phosphorylation and nuclear translocation of NF-κB p65 after irradiation and resulted in a reduced level of osteoclastogenesis in RAW264.7 cells after irradiation. In vivo studies involving Lyz2Cre;Crif1fl/fl mice possessing the myeloid-specific deletion of Crif1 demonstrated the alleviation of bone loss after irradiation when compared with Crif1fl/fl mice. Our findings demonstrate that Crif1 mediated the phosphorylation and nuclear translocation of NF-κB p65 and promoted osteoclastogenesis via the NF-κB signaling pathway after radiation exposure. Thus, our analysis revealed a specific role for Crif1 in the mediation of radiation-induced bone loss and may provide new insight into potential therapeutic strategies for radiation-induced bone loss.

Complications after proton radiotherapy in children, focusing on severe late complications. A complete Swedish cohort 2008-2019

BACKGROUND

Proton radiotherapy (RT) is an attractive tool to deliver local therapy with minimal dose to uninvolved tissue, however, not suitable for all patients. The aim was to explore complications, especially severe late complications (grades 3-4), following proton RT delivered to a complete Swedish cohort of paediatric patients aged <18 years treated 2008-2019.

MATERIAL AND METHODS

Data was downloaded from a national registry. Complications with a possible causation with RT are reported. Proton treatments until July 2015 was performed with a fixed horizontal 172 MeV beam (The Svedberg Laboratory (TSL), Uppsala) in a sitting position and thereafter with gantry-based pencil-beam scanning technique (Skandion Clinic, Uppsala) in a supine position.

RESULTS

219 courses of proton RT (77 at TSL and 142 at Skandion) were delivered to 212 patients (mean age 9.2 years) with various tumour types (CNS tumours 58%, sarcomas 26%, germ cell tumours 7%). Twenty-five patients had severe acute complications (skin, mucous membrane, pharynx/oesophagus, larynx, upper gastrointestinal canal, lower gastrointestinal canal, eyes, ears). Fifteen patients had severe late complications; with increased proportion over time: 4% at 1-year follow-up (FU), 5% at 3-year, 11% at 5-year. Organs affected were skin (1 patient), subcutaneous tissue (4), salivary glands (1), upper GI (1), bone (7), joints (2), CNS (2), PNS (1), eyes (1) and ears (5). Twenty-one of the 28 patients with 10-year FU had at least one late complication grades 1-4 and fourteen of them had more than one (2-5 each).

CONCLUSION

The most important result of our study is the relatively low proportion of severe late complications, comparable with other proton studies on various tumours. Furthermore, the numbers of late complications are lower than our own data set on a mixed population of photon and proton treated paediatric patients, assuring the safety of using proton therapy also in the clinical practice.

Proton and Carbon Ion Irradiation Changes the Process of Endochondral Ossification in an Ex Vivo Femur Organotypic Culture Model

Particle therapy (PT) that utilizes protons and carbon ions offers a promising way to reduce the side effects of radiation oncology, especially in pediatric patients. To investigate the influence of PT on growing bone, we exposed an organotypic rat ex vivo femur culture model to PT. After irradiation, histological staining, immunohistochemical staining, and gene expression analysis were conducted following 1 or 14 days of in vitro culture (DIV). Our data indicated a significant loss of proliferating chondrocytes at 1 DIV, which was followed by regeneration attempts through chondrocytic cluster formation at 14 DIV. Accelerated levels of mineralization were observed, which correlated with increased proteoglycan production and secretion into the pericellular matrix. Col2α1 expression, which increased during the cultivation period, was significantly inhibited by PT. Additionally, the decrease in ColX expression over time was more pronounced compared to the non-IR control. The chondrogenic markers BMP2, RUNX2, OPG, and the osteogenic marker ALPL, showed a significant reduction in the increase in expression after 14 DIV due to PT treatment. It was noted that carbon ions had a stronger influence than protons. Our bone model demonstrated the occurrence of pathological and regenerative processes induced by PT, thus building on the current understanding of the biological mechanisms of bone.

A Case of Radiation-Associated Vertebral Compression Fracture Mimicking Solitary Bone Metastasis of Lung Cancer

Radiation therapy plays an important role in the treatment of lung cancer. Although adverse effects of radiation are well known, they are sometimes difficult to be diagnosed. We report a case of a radiation-associated vertebral compression fracture which mimicked bone metastasis of lung cancer. The patient was a 57-year-old man diagnosed with lung squamous cell carcinoma (cT1aN2M0, c-stage IIIA). He received concurrent chemoradiotherapy (CRT) in combination with 6 weeks of weekly carboplatin plus paclitaxel and thoracic radiation of 60 Gy/30 fractions, followed by bi-weekly durvalumab for 12 months. On the last day of the 12-month durvalumab regimen, he complained of backache. Magnetic resonance imaging showed compression fracture of the seventh thoracic vertebra with the spinal cord compressed, and fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography demonstrated weak focal uptake only at the seventh thoracic vertebra. Although the fracture had been suspected to be bone metastasis, surgical biopsy revealed no evidence of malignancy. Since the seventh thoracic vertebra was included in the irradiation area, the patient was diagnosed with a radiation-associated fracture. Dual-energy X-ray absorptiometry of the lumbar vertebrae (L2 - 4) after the surgery revealed osteopenia. In conclusion, we successfully diagnosed the radiation-associated vertebral fracture caused by radical CRT. The fracture mimicked bone metastasis in preoperative imaging tests. Thus, surgical biopsy was useful for diagnosis.

The Use of Hydrogel-Based Materials for Radioprotection

Major causes of the radiation-induced disease include nuclear accidents, war-related nuclear explosions, and clinical radiotherapy. While certain radioprotective drug or bioactive compounds have been utilized to protect against radiation-induced damage in preclinical and clinical settings, these strategies are hampered by poor efficacy and limited utilization. Hydrogel-based materials are effective carriers capable of enhancing the bioavailability of compounds loaded therein. As they exhibit tunable performance and excellent biocompatibility, hydrogels represent promising tools for the design of novel radioprotective therapeutic strategies. This review provides an overview of common approaches to radioprotective hydrogel preparation, followed by a discussion of the pathogenesis of radiation-induced disease and the current states of research focused on using hydrogels to protect against these diseases. These findings ultimately provide a foundation for discussions of the challenges and future prospects associated with the use of radioprotective hydrogels.

Configuration of pathologic fractures in dogs with osteosarcoma following stereotactic body radiation therapy: A retrospective analysis

For some cases of canine appendicular osteosarcoma (OSA), limb-sparing treatment options are often desired, one of which is stereotactic body radiation therapy (SBRT). A major complication of SBRT is fracture of the irradiated bone at the site of treatment. The present study evaluated 127 appendicular OSA sites in 122 dogs treated with SBRT to identify the most common pathologic fracture locations and configurations. A total of 50 tumours experienced a pathologic fracture, and 38 had imaging sufficient to identify fracture configuration. The distal tibia was more likely to develop a fracture than other sites. Multiple types of fracture configuration (transverse, oblique, spiral and comminuted) were observed. The distal radius was significantly more likely to develop a transverse fracture than other sites. Documentation of fracture location and configuration leads to the identification of the forces contributing to fracture occurrence, since each configuration is a result of different forces acting on each affected bone. Such knowledge is imperative for the development of new approaches to diminish the occurrence of pathologic fractures.

Type H vessel/platelet-derived growth factor receptor β+ perivascular cell disintegration is involved in vascular injury and bone loss in radiation-induced bone damage

Collapse of the microvascular system is a prerequisite for radiation-induced bone loss. Since type H vessels, a specific bone vessel subtype surrounded by platelet-derived growth factor receptor β⁺ (PDGFRβ⁺ ) perivascular cells (PVCs), has been recently identified to couple angiogenesis and osteogenesis, we hypothesize that type H vessel injury initiates PDGFRβ⁺ PVC dysfunction, which contributes to the abnormal angiogenesis and osteogenesis after irradiation. In this study, we found that radiation led to the decrease of both type H endothelial cell (EC) and PDGFRβ⁺ PVC numbers. Remarkably, results from lineage tracing showed that PDGFRβ⁺ PVCs detached from microvessels and converted the lineage commitment from osteoblasts to adipocytes, leading to vascular injury and bone loss after irradiation. These phenotype transitions above were further verified to be associated with the decrease in hypoxia-inducible factor-1α (HIF-1α)/PDGF-BB/PDGFRβ signalling between type H ECs and PDGFRβ⁺ PVCs. Pharmacological blockade of HIF-1α/PDGF-BB/PDGFRβ signalling induced a phenotype similar to radiation-induced bone damage, while the rescue of this signalling significantly alleviated radiation-induced bone injury. Our findings show that the decrease in HIF-1α/PDGF-BB/PDGFRβ signalling between type H ECs and PDGFRβ⁺ PVCs after irradiation affects the homeostasis of EC-PVC coupling and plays a part in vascular damage and bone loss, which has broad implications for effective translational therapies.

Long-term pelvic fracture and overall mortality risk after pelvic cancer and pelvic radiation

BACKGROUND

The association of pelvic radiation with pelvic fracture risk has not been examined in prospective cohort settings with comprehensive fracture risk assessment, cancer-free comparison populations, and long-term follow-up. Our objective is to better characterize pelvic fracture and overall mortality risks in postmenopausal women participating in the Women's Health Initiative.

METHODS

A total of 135 743 Women's Health Initiative participants aged 50 to 79 years enrolled from 40 US clinical centers from 1993 to 1998 who had entry Fracture Risk Assessment Tool scores were eligible. Outcomes included pelvic cancer diagnosis, pelvic fracture occurrence, and mortality. Cox proportional hazards regression models were used to examine associations of pelvic cancer and pelvic radiation with pelvic fracture and mortality risk.

RESULTS

After 17.7 years (median) follow-up, 4451 pelvic cancers, 10 139 pelvic fractures, and 33 040 deaths occurred. In multivariable analyses, women with incident pelvic cancer, compared with women who remained pelvic cancer free, had higher pelvic fracture risk (hazard ratio [HR] = 1.26, 95% confidence interval [CI] = 1.11 to 1.43) and higher overall mortality risk (HR = 2.91, 95% CI = 2.77 to 3.05). Women with pelvic cancer treated with pelvic radiation, compared with women with pelvic cancer not treated with pelvic radiation, had higher pelvic fracture risk (HR = 1.98, 95% CI = 1.41 to 2.78) and higher overall mortality after pelvic cancer (HR = 1.32, 95% CI = 1.15 to 1.52).

CONCLUSIONS

Postmenopausal women with pelvic cancer, especially those receiving pelvic radiation, are at higher pelvic fracture risk and higher overall mortality risk. As therapeutic advances have reduced cancer mortality, attention to and interventions for pelvic fracture prevention may be important in pelvic cancer survivors.

Near-maximum rib dose is the most relevant risk factor for ipsilateral spontaneous rib fracture: a dosimetric analysis of breast cancer patients after radiotherapy

PURPOSE

Spontaneous rib fracture (SRF) is a common late complication in treated breast cancer patients. This study evaluated the incidence and risk factors of ipsilateral SRF after radiotherapy (RT) in breast cancer patients. In addition, we identified dosimetric parameters that were significantly associated with ipsilateral SRF.

METHODS

We retrospectively reviewed 2204 patients with breast cancer who underwent RT between 2014 and 2016, and were followed up with bone scans. We evaluated clinical risk factors for ipsilateral SRF. Dose-volume histogram analysis was also performed for patients (n = 538) whose dosimetric data were available. All ipsilateral ribs were manually delineated, and dosimetric parameters of the ribs were converted into the equivalent dose in 2 Gy fractions (EQD2).

RESULTS

Most of the patients with SRF (87.3%) were asymptomatic, and the remaining symptomatic patients complained of mild tenderness or chest wall discomfort; these symptoms all resolved within 6 months without any treatment. Ipsilateral SRF occurred in 14.5% of patients 3 years after RT. The median time to develop ipsilateral SRF was 15 months. In dosimetric analysis, near-maximum rib dose (D2cc) best predicted ipsilateral SRF. The cut-off value of D2cc was EQD2 52 Gy, as determined by receiver operating characteristic analysis. In multivariate analysis including dosimetric variables, D2cc EQD2 ≥ 52 Gy was the only significant risk factor for ipsilateral SRF.

CONCLUSION

Our data demonstrated that near-maximum rib dose was the best dosimetric parameter to predict ipsilateral SRF in RT-treated breast cancer patients. In addition, our results suggest that patients who received RT with exceeding rib dose cut-off value and had ipsilateral SRF on bone scan be recommended routine follow-up without additional imaging tests.

Fixation Principles for Pathologic Fractures in Metasatic Disease

The management of pathologic fractures differs from nonpathologic fractures with respect to preoperative evaluation, surgical strategies, adjuvant therapies, and complication rates. These issues must be understood to provide appropriate musculoskeletal care for patients with metastatic disease.

The dose-dependent impact of γ-radiation reinforced with backscatter from titanium on primary human osteoblasts

In head and neck cancer patients receiving dental implants prior to radiotherapy, backscatter from titanium increases the radiation dose close to the surface, and may affect the osseointegration. The dose-dependent effects of ionizing radiation on human osteoblasts (hOBs) were investigated. The hOBs were seeded on machined titanium, moderately rough fluoride-modified titanium, and tissue culture polystyrene, and cultured in growth- or osteoblastic differentiation medium (DM). The hOBs were exposed to ionizing γ-irradiation in single doses of 2, 6 or 10 Gy. Twenty-one days post-irradiation, cell nuclei and collagen production were quantified. Cytotoxicity and indicators of differentiation were measured and compared to unirradiated controls. Radiation with backscatter from titanium significantly reduced the number of hOBs but increased the alkaline phosphatase activity in both types of medium when adjusted to the relative cell number on day 21. Irradiated hOBs on the TiF-surface produced similar amounts of collagen as unirradiated controls when cultured in DM. The majority of osteogenic biomarkers significantly increased on day 21 when the hOBs had been exposed to 10 Gy, while the opposite or no effect was observed after lower doses. High doses reinforced with backscatter from titanium resulted in smaller but seemingly more differentiated subpopulations of osteoblasts.

Orthopedic therapeutic surgery for bone metastasis of liver cancer: Clinical efficacy and prognostic factors

Objectives

In this study, the objectives were to investigate the clinical efficacy of orthopedic therapeutic surgery (OTS) in patients with bone metastasis of liver cancer and explore the prognostic factors.

Methods

The electronic medical records of patients with bone metastasis of liver cancer in the Third Affiliated Hospital of Naval Medical University from September 2016 to August 2021 were retrospectively collected. A total of 53 patients were included. Patients were assigned to the OTS (n = 35) or the control group (n = 18) based on receiving orthopedic therapeutic surgery or conservative treatment. The pre/posttreatment Karnofsky Performance Status scale (KPS) and numeric rating scale (NRS) scores were compared. Univariate and multivariate Cox regression analyses were used to explore the prognostic factors affecting survival after bone metastasis. Logistic regression analyses were adopted to discover potential factors that contributed to greater KPS score improvement.

Results

The axial bone accounted for 69.8% of all bone metastases. The proportion of multiple bone metastases was 52.8%. After surgery, the median KPS score of the OTS group increased from 60 to 80 (p &lt; 0.001), and the median increase in the OTS group was higher than that of the control group (p = 0.033). The median NRS score of the OTS group declined from 6 to 2 after surgery (p &lt; 0.001), and the median decline in the OTS group was higher (p = 0.001). The median survival was 10 months in the OTS group vs. 6 months in the control group (p &lt; 0.001). Higher pretreatment KPS scores, undergoing liver primary lesion surgery, and undergoing orthopedic therapeutic surgery were protective factors of survival. Undergoing orthopedic therapeutic surgery greatly improved the KPS score.

Conclusions

Orthopedic therapeutic surgery for bone metastasis of liver cancer provides benefits to the quality of life. Patients who have their primary liver lesions removed, undergo orthopedic therapeutic surgery, and have a better physical condition before treatment tend to have longer survival.

Shining a FLASHlight on Ultrahigh Dose-Rate Radiation and Possible Late Toxicity

A recent study reported results from a clinical trial in cats and from experiments in mini-pigs in which a single dose of radiotherapy was delivered at ultrahigh dose rates (FLASH). There was acceptable acute toxicity; however, some animals suffered severe late toxicity, raising caution in the design of future trials. See related article by Rohrer Bley et al., p. 3814.

Systemic Literature Review on Multilevel Analysis of Radiation Effects on Bone Microarchitecture

Introduction

Modern radiation therapy has become an effective method to treat and monitor tumour growth in cancer patients. It has proved to be a successful way to minimise mortality rates. However, the adverse effects of radiation have been historical evidence in the clinical environment involving diminishing the quality and density of bone and causing fragility fracture to the bone in the long run. This systematic review was aimed at identifying and evaluating the effects of irradiation on morphology and mechanical properties of murine model bone in previous publications.

Methods

A systematic literature review was undertaken following the Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA) guidelines. A comprehensive literature search was performed using Scopus, Web of Science, and Science Direct databases (English only studies published between 2015 and 2020). The selected studies were evaluated according to three criteria: (1) criteria for study sample selection; (2) criteria for methodological procedures; and (3) criteria for detection and evaluation.

Results

The initial search strategy identified 1408 related studies, 8 of were included based on inclusion and exclusion criteria. This review revealed an association between bone destruction and the magnitude of time and dose postirradiation. We agreed that the effect of radiation on bone morphology and strength primarily is a later stage event but noticeable in both low (1 Gy) and high dose (30 Gy) radiation. Trabecular and cortical bone microstructures were significantly altered at irradiation and contralateral sites. Besides, the mechanical strength was significantly impacted in both shorter and longer periods.

Conclusion

Overall, the radiotherapy altered bone microstructures and substantially decreases bone mechanical properties. The alteration was related to quantity and the activity of the osteoblast and osteoclast. Early detection of those most at risk for radiation-induced bone alterations could lead to better prophylactic intervention decisions.

Adverse Radiation Therapy Effects in the Treatment of Head and Neck Tumors

Whether used as a single modality or as part of a combined approach, radiation therapy (RT) plays an essential role in the treatment of several head and neck malignancies. Despite the improvement in radiation delivery techniques, normal structures in the vicinity of the target area remain susceptible to a wide range of adverse effects. Given their high incidence, some of these effects are referred to as expected postradiation changes (eg, mucositis, sialadenitis, and edema), while others are considered true complications, meaning they should not be expected and can even represent life-threatening conditions (eg, radionecrosis, fistulas, and radiation-induced neoplasms). Also, according to their timing of onset, these deleterious effects can be divided into four groups: acute (during RT), subacute (within weeks to months), delayed onset (within months to years), and very delayed onset (after several years).The authors provide a comprehensive review of the most important radiation-induced changes related to distinct head and neck sites, focusing on their typical cross-sectional imaging features and correlating them with the time elapsed after treatment. Radiologists should not only be familiar with these imaging findings but also actively seek essential clinical data at the time of interpretation (including knowledge of the RT dose and time, target site, and manifesting symptoms) to better recognize imaging findings, avoid pitfalls and help guide appropriate management. ^© RSNA, 2022.

Effects of Tumor-Rib Distance and Dose-Dependent Rib Volume on Radiation-Induced Rib Fractures in Patients with Breast Cancer

This study aimed to investigate the effects of tumor-rib distance and dose-dependent rib volume on radiation-induced rib fractures (RIRFs) in patients with breast cancer. We retrospectively included 510 women with breast cancer who underwent surgical resection with adjuvant radiotherapy. The tumor-rib distance was measured using preoperative computed tomography (CT) images. Postoperative chest wall thickness and dose-dependent rib volumes, which are absolute rib volumes receiving >20 Gy (V20), 30 Gy (V30), 40 Gy (V40), 45 Gy (V45), and 50 Gy (V50), were measured from the stimulation CT images for radiation treatment planning. We assessed the relationship of RIRF with tumor-rib distance, postoperative chest wall thickness, and dose-dependent rib volumes. Patients with high values of tumor-rib distance and postoperative chest wall thickness had significantly lower risks of RIRF than those with low values. Patients with high values of V20, V30, V40, V45, and V50 had significantly higher risks of RIRF than those with low values. In a multivariate analysis, tumor-rib distance and all five dose-dependent rib volumes, as well as osteoporosis and radiation field, were independent risk factors for RIRF. Tumor-rib distance and dose-dependent rib volume were independent risk factors for RIRF in patients with breast cancer.

Influence of X-rays and gamma-rays on the mechanical performance of human bone factoring out intraindividual bone structure and composition indices

Doses of irradiation above 25 ​kGy are known to cause irreversible mechanical decay in bone tissue. However, the impact of irradiation doses absorbed in a clinical setting on the mechanical properties of bone remains unclear. In daily clinical practice and research, patients and specimens are exposed to irradiation due to diagnostic imaging tools, with doses ranging from milligray to Gray. The aim of this study was to investigate the influence of irradiation at these doses ranges on the mechanical performance of bone independent of inter-individual bone quality indices.

Therefore, cortical bone specimens (n ​= ​10 per group) from a selected organ donor were irradiated at doses of milligray, Gray and kilogray (graft tissue sterilization) at five different irradiation doses. Three-point bending was performed to assess mechanical properties in the study groups.

Our results show a severe reduction in mechanical performance (work to fracture: 50.29 ​± ​11.49 Nmm in control, 14.73 ​± ​1.84 Nmm at 31.2 ​kGy p ​≤ ​0.05) at high irradiation doses of 31.2 ​kGy, which correspond to graft tissue sterilization or synchrotron imaging. In contrast, no reduction in mechanical properties were detected for doses below 30 ​Gy. These findings are further supported by fracture surface texture imaging (i.e. more brittle fracture textures above 31.2 ​kGy).

Our findings show that high radiation doses (≥31.2 ​kGy) severely alter the mechanical properties of bone. Thus, irradiation of this order of magnitude should be taken into account when mechanical analyses are planned after irradiation. However, doses of 30 ​Gy and below, which are common for clinical and experimental imaging (e.g., radiation therapy, DVT imaging, CT imaging, HR-pQCT imaging, DXA measurements, etc.), do not alter the mechanical bending-behavior of bone.

Melatonin attenuates radiation-induced cortical bone-derived stem cells injury and enhances bone repair in postradiation femoral defect model

BACKGROUND

The healing of bone defects can be challenging for clinicians to manage, especially after exposure to ionizing radiation. In this regard, radiation therapy and accidental exposure to gamma (γ)-ray radiation have been shown to inhibit bone formation and increase the risk of fractures. Cortical bone-derived stem cells (CBSCs) are reportedly essential for osteogenic lineages, bone maintenance and repair. This study aimed to investigate the effects of melatonin on postradiation CBSCs and bone defect healing.

METHODS

CBSCs were extracted from C57BL/6 mice and were identified by flow cytometry. Then CBSCs were subjected to 6 Gy γ-ray radiation followed by treatment with various concentrations of melatonin. The effects of exogenous melatonin on the self-renewal and osteogenic capacity of postradiation CBSCs in vitro were analyzed. The underlying mechanisms involved in genomic stability, apoptosis and oxidative stress-related signaling were further analyzed by Western blotting, flow cytometry and immunofluorescence assays. Moreover, postradiation femoral defect models were established and treated with Matrigel and melatonin. The effects of melatonin on postradiation bone healing in vivo were evaluated by micro-CT and pathological analysis.

RESULTS

The decrease in radiation-induced self-renewal and osteogenic capacity were partially reversed in postradiation CBSCs treated with melatonin (P < 0.05). Melatonin maintained genomic stability, reduced postradiation CBSC apoptosis and intracellular oxidative stress, and enhanced expression of antioxidant-related enzymes (P < 0.05). Western blotting validated the anti-inflammatory effects of melatonin by downregulating interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) levels via the extracellular regulated kinase (ERK)/nuclear factor erythroid 2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) signaling pathway. Melatonin was also found to exhibit antioxidant effects via NRF2 signaling. In vivo experiments demonstrated that the newly formed bone in the melatonin plus Matrigel group had higher trabecular bone volume per tissue volume (BV/TV) and bone mineral density values with lower IL-6 and TNF-α levels than in the irradiation and the Matrigel groups (P < 0.05).

CONCLUSION

This study suggested that melatonin could protect CBSCs against γ-ray radiation and assist in the healing of postradiation bone defects.

Treatment of Radiation Bone Injury with Transplanted hUCB-MSCs via Wnt/β-Catenin

Radiation-induced bone injury (RIBI) is one of the complications after radiotherapy for malignant tumors. However, there are no effective measures for the treatment of RIBI in clinical practice, and the mechanism of RIBI is unclear. We use a single high-dose ionizing radiation (6Gy) to analyze the effect of radiotherapy on osteoblast function. Human umbilical cord blood mesenchymal stem cells (hUCB-MSCs) were cocultured with irradiated osteoblasts to examine their therapeutic effects and mechanisms on osteoblast injury. The hUCB-MSC transplantation mouse model is used to confirm the in vivo role of hUCB-MSC treatment in radiation bone injury. Western blot analysis, qRT-PCR, immunohistochemistry, and immunofluorescence staining were used to analyze gene expression and angiogenesis. The apoptosis and migration of osteoblasts were measured by Hoechst staining, scratch test, and transwell. The differentiation of osteoblasts was measured by ALP and Alizarin red staining and transmission electron microscopy. The bone-related parameters of mice were evaluated by micro-CT analysis. We found that radiation can damage the DNA of osteoblasts; induce apoptosis; reduce the differentiation, migration, and adhesion of osteoblasts, leading to lipogenesis of bone marrow mesenchymal stem cells (BMSCs) and reducing the source of osteoblasts; and increase the number of osteoclasts in bone tissue, while MSC treatment prevents these changes. Our results reveal the inhibitory effect of radiation on osteoblast function. hUCB-MSCs can be used as a therapeutic target for the development of new therapeutic strategies for radiotherapy of bone injury diseases.

Efficacy and safety of magnetic resonance-guided focused ultrasound for the treatment of painful bone metastases: a systematic review and meta-analysis

OBJECTIVE

To report the safety and efficacy of magnetic resonance-guided focused ultrasound (MRgFUS) in the treatment of painful bone metastases through a systematic review and meta-analysis of pain scores before and after MRgFUS treatment and post-treatment adverse events.

MATERIALS AND METHODS

A comprehensive literature search of PubMed and Embase databases was performed for studies evaluating the efficacy and/or safety of MRgFUS. The mean difference of pain scores (10-point visual analogue scale or numerical rating scale) between baseline and 1-month/3-month pain scores was collected and analyzed in a pooled meta-analysis. Post-treatment adverse events based on the Common Terminology Criteria for Adverse Events (CTCAE) grading were recorded and the pooled prevalence was calculated.

RESULTS

A total of 33 studies published between 2007 and 2019 were collected, resulting in a total sample size of 1082 patients. The majority of the studies were prospective with a reported follow-up period of 3 months. The pooled proportion of patients that achieved pain relief from MRgFUS (complete response or partial response [≥ 2-point improvement of pain score]) was 79% (95% CI 73-83%). The pooled 1-month and 3-month mean difference in pain score were - 3.8 (95% CI - 4.3; - 3.3) and - 4.4 (95% CI - 5.0; - 3.7), respectively. The overall rate of high-grade (CTCAE grade 3 or higher) and low-grade (CTCAE grade 2 or lower) MRgFUS-related adverse events were 0.9% and 5.9%, respectively.

CONCLUSION

MRgFUS is an effective procedure that is able to provide significant pain palliation for patients with symptomatic bone metastases with a favorable safety profile.

The role of senolytics in osteoporosis and other skeletal pathologies

The skeletal system undergoes irreversible structural deterioration with aging, leading to increased fracture risk and detrimental changes in mobility, posture, and gait. This state of low bone mass and microarchitectural changes, diagnosed as osteoporosis, affects millions of individuals worldwide and has high clinical and economic burdens. Recently, pre-clinical studies have linked the onset of age-related bone loss with an accumulation of senescent cells in the bone microenvironment. These senescent cells appear to be causal to age-related bone loss, as targeted clearance of these cells leads to improved bone mass and microarchitecture in old mice. Additionally, other pathologies leading to bone loss that result from DNA damage, such as cancer treatments, have shown improvements after clearance of senescent cells. The development of new therapies that clear senescent cells, termed "senolytics", is currently underway and may allow for the modulation of bone loss that results from states of high senescent cell burden, such as aging.

Radiation-Induced Osteocyte Senescence Alters Bone Marrow Mesenchymal Stem Cell Differentiation Potential via Paracrine Signaling

Cellular senescence and its senescence-associated secretory phenotype (SASP) are widely regarded as promising therapeutic targets for aging-related diseases, such as osteoporosis. However, the expression pattern of cellular senescence and multiple SASP secretion remains unclear, thus leaving a large gap in the knowledge for a desirable intervention targeting cellular senescence. Therefore, there is a critical need to understand the molecular mechanism of SASP secretion in the bone microenvironment that can ameliorate aging-related degenerative pathologies including osteoporosis. In this study, osteocyte-like cells (MLO-Y4) were induced to cellular senescence by 2 Gy γ-rays; then, senescence phenotype changes and adverse effects of SASP on bone marrow mesenchymal stem cell (BMSC) differentiation potential were investigated. The results revealed that 2 Gy irradiation could hinder cell viability, shorten cell dendrites, and induce cellular senescence, as evidenced by the higher expression of senescence markers p16 and p21 and the elevated formation of senescence-associated heterochromatin foci (SAHF), which was accompanied by the enhanced secretion of SASP markers such as IL-1α, IL-6, MMP-3, IGFBP-6, resistin, and adiponectin. When 0.8 μM JAK1 inhibitors were added to block SASP secretion, the higher expression of SASP was blunted, but the inhibition in osteogenic and adipogenic differentiation potential of BMSCs co-cultured with irradiated MLO-Y4 cell conditioned medium (CM- 2 Gy) was alleviated. These results suggest that senescent osteocytes can perturb BMSCs’ differential potential via the paracrine signaling of SASP, which was also demonstrated by in vivo experiments. In conclusion, we identified the SASP factor partially responsible for the degenerative differentiation of BMSCs, which allowed us to hypothesize that senescent osteocytes and their SASPs may contribute to radiation-induced bone loss.

Femoral fracture in primary soft-tissue sarcoma of the thigh treated with radiation therapy: indications for prophylactic intramedullary nail

INTRODUCTION

Post-radiation fractures of the femur (PRF) are difficult to treat and are associated with a high risk of delayed union and non-union. We report a series of patients affected by soft tissue sarcoma (STS) of the thigh, treated with limb-sparing surgery and perioperative radiotherapy (RT), to analyse post-radiotherapy femur fracture (FF) rate and its management.

MATERIAL AND METHODS

547 patients treated with surgery and RT for a deep primary STS of the thigh were included. "Periosteal stripping" and "bone tangential resection" were performed in case of tumor invasion. In the case of complete bone involvement, the patient received its complete resection and econstruction.

RESULTS

Twenty-three (4.3%) patients underwent surgical procedures involving periosteum and cortical bone. In 11 (2.0%) patients a bone resection was required because of massive bone involvement. Six out of these 11 (54.5%) patients developed major complications (infection and aseptic loosening). At the time of STS excision, 11 patients (2.0%) underwent prophylactic intramedullary nailing (PIN). PRF occurred in 15 patients (3.0%) at a median follow up of 52 months (range 3-151). Among patients who developed PRF, three were treated with a prosthesis (no complications) and eight nailing (7/8, 87.5% did not heal and developed a non-union).

CONCLUSIONS

Given the potentially devastating complication of a PRF, PIN should be considered. We suggest prophylactic IM nail in patients at higher risk the time of STS excision. In other cases, IM nail can be postponed in the following years considering the prognosis.

Radiotherapy and Surgical Advances in the Treatment of Metastatic Spine Tumors: A Narrative Review

Spine tumors encompass a wide range of diseases with a commensurately broad spectrum of available treatments, ranging from radiation for spinal metastases to highly invasive en bloc resection for primary vertebral column malignancies. This high variability in treatment approaches stems both from variability in the goals of surgery (e.g., oncologic cure vs. symptom palliation) and from the significant advancements in surgical technologies that have been made over the past 2 decades. Among these advancements are improvements in surgical technique, namely minimally invasive approaches, increased availability of focused radiation modalities (e.g., proton therapy and linear accelerator devices), and new surgical technologies, such as carbon fiber-reinforced polyether ether ketone rods. In addition, several groups have described nonsurgical interventions, such as vertebroplasty and kyphoplasty for spinal instability secondary to pathologic fracture, and lesion ablation with spinal laser interstitial thermoablation, radiofrequency ablation, or cryoablation. We provide an overview of the latest technological advancements in spinal oncology and their potential usefulness for modern spinal oncologists.

Extracellular Vesicles for the Treatment of Radiation Injuries

Normal tissue injury from accidental or therapeutic exposure to high-dose radiation can cause severe acute and delayed toxicities, which result in mortality and chronic morbidity. Exposure to single high-dose radiation leads to a multi-organ failure, known as acute radiation syndrome, which is caused by radiation-induced oxidative stress and DNA damage to tissue stem cells. The radiation exposure results in acute cell loss, cell cycle arrest, senescence, and early damage to bone marrow and intestine with high mortality from sepsis. There is an urgent need for developing medical countermeasures against radiation injury for normal tissue toxicity. In this review, we discuss the potential of applying secretory extracellular vesicles derived from mesenchymal stromal/stem cells, endothelial cells, and macrophages for promoting repair and regeneration of organs after radiation injury.

Osteocyte Cellular Senescence

PURPOSE OF REVIEW

Senescent cells are now known to accumulate in multiple tissues with aging and through their inflammation (the senescence-associated secretory phenotype, SASP) contribute to aging and chronic diseases. Here, we review the roles of senescent osteocytes in the context of bone loss.

RECENT FINDINGS

Numerous studies have established that senescent osteocytes accumulate in the bone microenvironment with aging in mice and in humans. Moreover, at least in mice, elimination of senescent cells results in attenuation of age-related bone loss. Osteocyte senescence also occurs in response to other cellular stressors, including radiotherapy, chemotherapy, and metabolic dysfunction, where it appears to mediate skeletal deterioration. Osteocyte senescence is linked to bone loss associated with aging and other conditions. Senescent osteocytes are potential therapeutic targets to alleviate skeletal dysfunction. Additional studies better defining the underlying mechanisms as well as translating these exciting findings from mouse models to humans are needed.

Effects of long-term in vivo micro-CT imaging on hallmarks of osteopenia and frailty in aging mice

In vivo micro-CT has already been used to monitor microstructural changes of bone in mice of different ages and in models of age-related diseases such as osteoporosis. However, as aging is accompanied by frailty and subsequent increased sensitivity to external stimuli such as handling and anesthesia, the extent to which longitudinal imaging can be applied in aging studies remains unclear. Consequently, the potential of monitoring individual mice during the entire aging process-from healthy to frail status-has not yet been exploited. In this study, we assessed the effects of long-term in vivo micro-CT imaging-consisting of 11 imaging sessions over 20 weeks-on hallmarks of aging both on a local (i.e., static and dynamic bone morphometry) and systemic (i.e., frailty index (FI) and body weight) level at various stages of the aging process. Furthermore, using a premature aging model (PolgA(D257A/D257A)), we assessed whether these effects differ between genotypes. The 6th caudal vertebrae of 4 groups of mice (PolgA(D257A/D257A) and PolgA(+/+)) were monitored by in vivo micro-CT every 2 weeks. One group was subjected to 11 scans between weeks 20 and 40 of age, whereas the other groups were subjected to 5 scans between weeks 26-34, 32-40 and 40-46, respectively. The long-term monitoring approach showed small but significant changes in the static bone morphometric parameters compared to the other groups. However, no interaction effect between groups and genotype was found, suggesting that PolgA mutation does not render bone more or less susceptible to long-term micro-CT imaging. The differences between groups observed in the static morphometric parameters were less pronounced in the dynamic morphometric parameters. Moreover, the body weight and FI were not affected by more frequent imaging sessions. Finally, we observed that longitudinal designs including baseline measurements at young adult age are more powerful at detecting effects of in vivo micro-CT imaging on hallmarks of aging than cross-sectional comparisons between multiple groups of aged mice subjected to fewer imaging sessions.

Spontaneous Rib Fractures After Breast Cancer Treatment Based on Bone Scans: Comparison Of Conventional Versus Hypofractionated Radiotherapy

BACKGROUND

Spontaneous rib fractures (SRFs) are defined as fractures without apparent blunt force trauma. This study evaluated the incidence and risk factors of SRFs after treatment of patients with breast cancer based on bone scans. In addition, we analyzed radiation-associated SRFs and identified radiotherapy (RT) factors related to SRF.

PATIENTS AND METHODS

We retrospectively reviewed 1265 patients with breast cancer who underwent surgery in 2015 at our institution, and were followed-up with at least 3 bone scans. Bone scans were conducted approximately every 12 months after breast cancer treatment. The endpoint was SRF detected by bone scan. In this study, 754 (60%) patients were treated with chemotherapy, 867 (69%) with RT, and 946 (75%) with anti-hormone therapy.

RESULTS

The median follow-up duration was 37.5 months. A total of 209 (16.5%) patients experienced SRFs during follow-up. The incidence of SRFs increased sharply during the 3-year follow-up period after completion of treatment. In multivariate analyses, abnormal bone density, chemotherapy, and RT were significant risk factors for SRFs. In patients treated with RT (n = 867), 159 (18%) rib fractures occurred: 127 (80%) in the ipsilateral breast and 32 (20%) in the contralateral breast. Among the patients with ipsilateral SRFs who received tumor bed boost (n = 84), the SRF occurred inside the boost field in 80 (95%) cases. Multivariate analysis of RT subgroups showed that hypofractionated RT increased the rate of SRFs (P = .002).

CONCLUSIONS

Most of the rib fractures that occurred after treatment were spontaneous. Hypofractionated RT increased the risk of ipsilateral rib fractures in RT-treated patients.

Musculoskeletal Effects of Cancer and Cancer Treatment

Improvements in cancer treatment have led to prolonged survival and increased rates of cure. An estimated 14 million cancer survivors live in the United States. The cornerstones of cancer treatment, including radiation, chemotherapy, and surgery, give rise to a host of chronic health conditions, some of which affect the musculoskeletal system. As survivorship continues to improve, orthopaedic surgeons across all subspecialties will be tasked with managing these complications of treatment. This article reviews orthopaedic health concerns secondary to cancer treatment that are likely to present to orthopaedic surgeons for evaluation, such as osteoporosis, osteonecrosis, secondary malignancies, radiation-associated fractures, exercise tolerance, and perioperative evaluation.

A Multimodality Image Guided Precision Radiation Research Platform: Integrating X-ray, Bioluminescence, and Fluorescence Tomography With Radiation Therapy

PURPOSE

Small animal irradiation is crucial to the investigation of radiobiological mechanisms. The paradigm of clinical radiation therapy is trending toward high-precision, stereotactic treatment. However, translating this scheme to small animal irradiation is challenging owing to the lack of high-quality image guidance. To overcome this obstacle, we developed a multimodality image guided precision radiation platform.

METHODS AND MATERIALS

The platform consists of 4 modules: x-ray computed tomography (CT), bioluminescence tomography (BLT), fluorescence molecular tomography (FMT), and radiation therapy. CT provides animal anatomy and material density for radiation dose calculation, as well as body contour for BLT and FMT reconstruction. BLT and FMT provide tumor localization to guide radiation beams and molecular activity to evaluate treatment outcome. Furthermore, we developed a Monte Carlo-based treatment planning system (TPS) for 3-dimensional dose calculation, calibrated it using radiochromic films sandwiched in a water-equivalent phantom, and validated it using in vivo dosimeters surgically implanted into euthanized mice (n = 4). Finally, we performed image guided irradiation on mice bearing orthotopic breast and prostate tumors and confirmed radiation delivery using γH2AX histology.

RESULTS

The Monte Carlo-based TPS was successfully calibrated by benchmarking simulation dose against film measurement. For in vivo dosimetry measured in the euthanized mice, the average difference between the TPS calculated dose and measured dose was 3.86% ± 1.12%. Following the TPS-generated treatment plan, we successfully delivered 20 Gy dose to an animal bearing an orthotopic prostate tumor using 4 BLT-guided radiation beams and 5 Gy dose to an animal bearing an orthotopic breast tumor using a single FMT-guided radiation beam. γH2AX histology presented significantly more DNA damage in irradiated tumors and thus validated the dose delivery accuracy.

CONCLUSIONS

Combined with Monte Carlo TPS, this multimodality CT/BLT/FMT image guided small animal radiation platform can specifically localize tumors, accurately calculate dose distribution, precisely guide radiation delivery, and molecularly evaluate treatment response. It provides an advanced toolset for radiobiology and translational cancer research.

CR6-interacting factor-1 contributes to osteoclastogenesis by inducing receptor activator of nuclear factor κB ligand after radiation

BACKGROUND

Radiation induces rapid bone loss and enhances bone resorption and adipogenesis, leading to an increased risk of bone fracture. There is still a lack of effective preventive or therapeutic method for irradiation-induced bone injury. Receptor activator of nuclear factor κB ligand (RANKL) provides the crucial signal to induce osteoclast differentiation and plays an important role in bone resorption. However, the mechanisms of radiation-induced osteoporosis are not fully understood.

AIM

To investigate the role of CR6-interacting factor-1 (Crif1) in osteoclastogenesis after radiation and its possible mechanism.

METHODS

C57BL/6 mice were exposed to Co-60 gamma rays and received 5 Gy of whole-body sublethal irradiation at a rate of 0.69 Gy/min. For in vitro study, mouse bone marrow mesenchymal stem/stromal cells (BM-MSCs) were irradiated with Co-60 at a single dose of 9 Gy. For osteoclast induction, monocyte-macrophage RAW264.7 cells were cocultured with mouse BM-MSCs for 7 d. ClusPro and InterProSurf were used to investigate the interaction interface in Crif1 and protein kinase cyclic adenosine monophosphate (cAMP)-activited catalytic subunit alpha complex. Virtual screening using 462608 compounds from the Life Chemicals database around His120 of Crif1 was carried out using the program Autodock_vina. A tetrazolium salt (WST-8) assay was carried out to study the toxicity of compounds to different cells, including human BM-MSCs, mouse BM-MSCs, and Vero cells.

RESULTS

Crif1 expression increased in bone marrow cells after radiation in mice. Overexpression of Crif1 in mouse BM-MSCs and radiation exposure could increase RANKL secretion and promote osteoclastogenesis in vitro. Deletion of Crif1 in BM-MSCs could reduce both adipogenesis and RANKL expression, resulting in the inhibition of osteoclastogenesis. Deletion of Crif1 in RAW264.7 cells did not affect the receptor activator of nuclear factor κB expression or osteoclast differentiation. Following treatment with protein kinase A (PKA) agonist (forskolin) and inhibitor (H-89) in mouse BM-MSCs, Crif1 induced RANKL secretion via the cAMP/PKA pathway. Moreover, we identified the Crif1-protein kinase cyclic adenosine monophosphate-activited catalytic subunit alpha interaction interface by in silico studies and shortlisted interface inhibitors through virtual screening on Crif1. Five compounds dramatically suppressed RANKL secretion and adipogenesis by inhibiting the cAMP/PKA pathway.

CONCLUSION

Crif1 promotes RANKL expression via the cAMP/PKA pathway, which induces osteoclastogenesis by binding to receptor activator of nuclear factor κB on monocytes-macrophages in the mouse model. These results suggest a role for Crif1 in modulating osteoclastogenesis and provide insights into potential therapeutic strategies targeting the balance between osteogenesis and adipogenesis for radiation-induced bone injury.

Effects of ionizing radiation on woven bone: influence on the osteocyte lacunar network, collagen maturation, and microarchitecture

OBJECTIVES

Evaluate the effects of ionizing radiation on microarchitecture, the osteocyte lacunar network, and collagen maturity in a bone repair site.

MATERIALS AND METHODS

Bone defects were created on tibias of 20 New Zealand rabbits. After 2 weeks, the animals were randomly divided into (n = 10) NoIr (nonirradiated group) and Ir (irradiated group). In the Ir, the animals received single-dose irradiation of 30 Gy on the tibia and were euthanized after 2 weeks. Bone microarchitecture parameters were analyzed by using micro-CT, and the osteocyte lacunar network, bone matrix, and collagen maturation by histomorphometric analysis. The data were analyzed using unpaired Student's t test (α = 0.05).

RESULTS

Trabecular thickness in Ir was lower than that in NoIr (P = 0.028). No difference was found for bone volume fraction and bone area. Lacunae filled with osteocytes were more numerous (P < 0.0001) in NoIr (2.6 ± 0.6) than in Ir (1.97 ± 0.53). Empty lacunae were more prevalent (P < 0.003) in Ir (0.14 ± 0.10) than in NoIr (0.1 ± 0.1). The mean osteocyte lacunae size was higher (P < 0.01) in Ir (15.4 ± 4.41) than in NoIr (12.7 ± 3.7). Picrosirius red analysis showed more (P < 0.05) mature collagen in NoIr (29.0 ± 5.3) than in Ir (23.4 ± 4.5). Immature collagen quantification revealed no difference between groups.

CONCLUSIONS

Ionizing radiation compromised bone formation and an impairment in bone repair in irradiated woven bone was observed.

CLINICAL RELEVANCE

Before radiotherapy, patients usually need surgical intervention, which may be better performed, if clinicians understand the repair process in irradiated bone, using novel approaches for treating these individuals.

Management of Osteoporosis in Survivors of Adult Cancers With Nonmetastatic Disease: ASCO Clinical Practice Guideline

PURPOSE

The aim of this work is to provide evidence-based guidance on the management of osteoporosis in survivors of adult cancer.

METHODS

ASCO convened a multidisciplinary Expert Panel to develop guideline recommendations based on a systematic review of the literature.

RESULTS

The literature search of the 2018 systematic review by the US Preventive Services Task Force in the noncancer population was used as the evidentiary base upon which the Expert Panel based many of its recommendations. A total of 61 additional studies on topics and populations not covered in the US Preventive Services Task Force review were also included. Patients with cancer with metastatic disease and cancer survival outcomes related to bone-modifying agents are not included in this guideline.

RECOMMENDATIONS

Patients with nonmetastatic cancer may be at risk for osteoporotic fractures due to baseline risks or due to the added risks that are associated with their cancer therapy. Clinicians are advised to assess fracture risk using established tools. For those patients with substantial risk of osteoporotic fracture, the clinician should obtain a bone mineral density test. The bone health of all patients may benefit from optimizing nutrition, exercise, and lifestyle. When a pharmacologic agent is indicated, bisphosphonates or denosumab at osteoporosis-indicated dosages are the preferred interventions.

[Differential diagnoses of osteonecrosis of large joints]

Subchondral insufficiency fractures and idiopathic bone marrow edema syndrome are the most important differential diagnoses to be distinguished from osteonecrosis because they have a deviating and as a rule more favorable prognosis and also different therapeutic strategies. Osteochondritis dissecans represents a different entity in many respects, which should not be confused or unified with osteonecrosis. Based on recent knowledge intractable subchondral insufficiency fractures may be the underlying cause of rapidly destructive osteoarthritis at least in some cases. Septic involvement of bone and joints can eo ipso cause severe articular damage due to direct destruction but also secondary to septic vascular occlusion resulting in septic osteonecrosis. Whereas bone marrow infiltrating systemic diseases and the therapeutic regimens can lead to osteonecrosis, bone tumors or tumor-like diseases, rarely pose a differential diagnostic problem with respect to the differentiation from osteonecrosis.

Pelvic insufficiency fractures, dose volume parameters and plan optimization after radiotherapy for rectal cancer

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High rates of PIF are detected 3 years after VMAT based CRT for rectal cancer.

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Patients with PIFs received non-significantly higher V30 Gy to sacroiliac joints.

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3 arc VMAT techniques can be optimized for bone.

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Proton beam therapy has the potential for further optimization for bone.

Pelvic insufficiency fractures (PIF) is a known but under-acknowledged late effect of pelvic radiotherapy. In rectal cancer, studies describing incidence of PIF and relation to dose volume relationships are lacking. The aim of this study was (i) to analyse dose volume histograms (DVH) from pelvic bones in patients with and without PIF, and (ii) to determine bone sparing capacity of 2 and 3 arc volumetric arc therapy (VMAT), intensity modulated radiotherapy (IMRT) and proton beam therapy (PBT), in rectal cancer patients treated with chemoradiotherapy (CRT).

Material and methods

Patients treated with CRT for primary rectal cancer underwent a 3-year pelvic MRI for identification of PIFs. Bone structures were retrospectively delineated, and DVHs were re-calculated. Comparative planning was done with 2 (original) and 3 arc VMAT, fixed field IMRT and PBT plans.

Results

27 patients (18 men, mean age 64 years) were included and PIFs were identified in 9 (33%), most (n = 6) had multiple fracture sites. In general, patients with PIFs received higher doses to pelvic bones, and V30 Gy to the sacroiliac joint was non-significantly higher in patients with PIF 68.5% (60.1–69.3 IQR) vs. 56% (54.1–66.6 IQR), p = 0.064. Comparative planning showed that especially 3 arc VMAT and proton beam therapy could be optimized for bone.

Conclusions

Patients, treated with VMAT based CRT for rectal cancer, have high rates of PIFs after 3 years. Patients with PIFs tended to have received higher doses to sacroiliac joints. Comparative planning demonstrated most pronounced bone sparing capacity of 3 arc VMAT and with PBT having the potential to further lower doses. These results should be validated in larger and preferably prospective cohorts.

Translational and basic science opportunities in palliative care and radiation oncology

Radiation therapy is commonly used in the metastatic setting to palliate pain, neurological deficits, bleeding and other complications of metastatic disease, allowing patients to live longer and have better quality of life. Despite the effective use of radiation and other palliative treatment modalities, many patients continue to experience poorly controlled pain and other serious sequelae of their disease, underscoring the need for additional research in this area. In this review we highlight recent developments impacting the fields of palliative care and radiation oncology and describe opportunities for research and innovation including studies of tumor microenvironment, identification of effective biomarkers of tumor response and combinatorial treatments with new systemic agents. It is our hope that progress in these fields will improve the lives of patients living with advanced malignancies.