Gy Group Research Articles

Silence of circBANP increases radiosensitivity of colorectal cancer cells and inhibits growth of subcutaneous xenografts by up-regulating miR-338-3p expression

Objective: To investigate the effect of circBANP on radiosensitivity of colorectal cancer cells and subcutaneous transplanted tumor in nude mice and its potential molecular mechanism. Methods: The carcinoma and adjacent normal mucosal tissues of 20 patients with colorectal cancer who were surgically resected in Henan People's Hospital from January 2018 to January 2019 were selected. The radio-resistant colorectal cancer cell LoVo/R was established. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expressions of circBANP and miR-338-3p. The radiation sensitivity was determined by cell clone formation experiment. Cell vitality was detected by using methyl thiazolyl tetrazolium (MTT). The expressions of autophagy-related protein microtubule-associated protein light chain 3 (LC3) and p62 were detected by western blot. The fluorescence intensity of LC3 in cells was detected by immunofluorescence assay. The downstream microRNAs (miRNAs) of circBANP were predicted by Circular RNA Interactome website and further verified by dual luciferase reporter gene assay. The transplanted tumor model of LoVo/R cells in nude mice was established, and the effect of circBANP on the growth of transplanted tumor after radiation was observed. Results: The expression levels of circBANP and miR-338-3p in colorectal cancer tissues were 3.21+ 0.29 and 0.47+ 0.04, respectively, which were significantly higher than 1.00+ 0.07 and 1.00+ 0.05 in adjacent tissues (P<0.05). The circBANP expression level of LoVo/R cells was 3.21±0.34, higher than 1.00±0.07 of LoVo cells (P<0.05), and the expression level of miR-338-3p of LoVo/R cells was 0.33±0.04, lower than 1.00±0.08 of LoVo cells (P<0.05). After 4 Gy irradiation, compared with the control group, the viability of LoVo/R cells in the circBANP silencing group [(34±4)% vs (62±6)%, P<0.05], the cell survival fraction (0.07±0.02 vs 0.27±0.04, P<0.05) were decreased, and the radiation sensitization ratio was 1.843, the expression of LC3Ⅱ/Ⅰin LoVo/R cells increased while p62 expression decreased, the cell autophagy was observed. Autophagy inhibitor chloroquine reversed the increased expression of LC3Ⅱ/Ⅰ and inhibited expression of p62 in LoVo/R cells induced by radiation, and promoted the suppression of cell viability and survival induced by radiation, the radiotherapy sensitization ratio was 1.780. Compared with control group after 4 Gy irradiation, the relative fluorescence intensity of LC3 in circBANP silencing LoVo/R cells decreased (0.11±0.01 vs 1.00±0.12, P<0.05), the expression of LC3-Ⅱ/Ⅰdecreased (1.25±0.13 vs 3.84±0.39, P<0.05) while p62 expression increased (2.76±0.29 vs 1.00±0.08, P<0.05). As predicted by Circular RNA Interactome website and confirmed by double luciferase reporter gene assay, miR-338-3p was the target gene of circBANP. The relative fluorescence intensity of LC3 in circBANP silencing + anti-miR-338-3p + 4 Gy group increased (7.32±0.72 vs 1.00±0.09, P<0.05), the expression level of LC3-Ⅱ/Ⅰ increased (4.13±0.43 vs 2.31±0.23, P<0.05) while p62 expression decreased (0.34±0.03 and 1.00±0.11, P<0.05), the radiotherapy sensitization ratio was 0.596. Nude mice subcutaneously transplanted tumor experiment showed that the tumor volume and weight of circBANP silencing group on 13, 16, 19, 22, 25, 28, and 31 days were lower than those of control group (P<0.05), while the tumor volume and weight of circBANP silencing + anti-miR-338-3p group on days of 13, 16, 19, 22, 25, 28 and 31 after inoculated were higher than those of circBANP+ anti-miR-NC group (P<0.05). Conclusions: CircBANP can regulate the radiosensitivity of colorectal cancer cells by regulating the expression of miR-338-3p, and affect the growth of transplanted tumor in nude mice. CircBANP may be a potential target for enhancing radiosensitivity of colorectal cancer cells.

Treatment outcomes of stereotactic body radiation therapy using a real-time tumor-tracking radiotherapy system for hepatocellular carcinomas.

To report the outcomes of stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system for hepatocellular carcinoma patients. From January 2005 to July 2018, 63 patients with 74 lesions with a maximum diameter ≤52mm were treated by stereotactic body radiotherapy using a real-time tumor-tracking radiotherapy system. No patient with a Child-Pugh Score ≥9 was included, and 85.6% had a score of 5 or 6. Using the biological effective dose (BED) with an α/β ratio of 10 (BED10 ), the median dose in BED10 at the reference point was 76.8Gy (range 60-122.5Gy). Overall survival (OS) and local control rates were assessed using the Kaplan-Meier method. With a median follow-up period of 24.6months (range 0.9-118.4months), the 1-year and 2-year OS rates were 86.8% (95% confidence interval [95% CI] 75.8-93.3) and 71.1% (57.8-81.6), respectively. The 2-year OS was 89.6% in patients with the baseline modified albumin-bilirubin (mALBI) grade =1, and 61.7% in patients with grade ≥2a. In the multivariate analysis, the mALBI grade (=1 vs. ≥2a) was a significant factor for OS (p=0.028, 95% CI 1.11-6.18). The 1-year and 2-year local control rates were 100% (100-100%) and 92.0% (77.5-97.5%). The local control rates were significantly higher in the BED10 ≥100Gy group than in the BED10 <100Gy group (2-year 100% vs. 86.5%, p=0.049) at the reference point. This retrospective study of stereotactic body radiotherapy using real-time tumor-tracking radiotherapy for hepatocellular carcinoma showed favorable outcomes with lower incidence of toxicities, especially in patients treated with BED10 ≥100Gy to the reference point.

Abstract PO-096: Blocking the CXCL12/CXCR4 pathway both radiosensitizes brain metastases in mice and protects against radiation-induced cognitive dysfunction following whole brain irradiation in rats

Abstract We have previously shown using an antagonist of CXCR4 (plerixafor) with brain implanted tumors in mice(1)or by blocking CXCL12 by olaptesed pegol (ola-peg) with chemically-induced brain tumors in rats(2) that the radiation response of the tumors is markedly enhanced by blocking the CXCL12/CXCR4 pathway. In the present study we aimed to test whether a similar radiation enhancement is produced in mice with multiple brain metastases, and in addition, in preparation for a clinical trial of whole brain irradiation (WBI) with plerixafor, we sought to determine whether blocking the CXCL12/CXCR4 pathway would affect the cognitive dysfunction of rats given WBI. In the brain metastasis study we produced multiple brain metastases by injection of the luciferase transduced brain-tropic human breast triple negative cancer cell line MDA-MB-231 B3 into the internal carotid artery of nude mice. Adding the CXCL12 antagonist ola-peg after irradiation produced both a doubling of the regrowth delay (as monitored by bioluminescence imaging) and median survival time compared to irradiation alone. We also showed that similar to the brain implanted human glioblastoma studies that blocking the pathway prevented the radiation-induced influx of tumor associated macrophages (TAMs) into the brain metastases. In preliminary studies with cognitive dysfuction we gave adult Sprague-Dawley rats whole brain irradiation of 5, 10, 15 or 20 Gy and 2 months later measured their short term memory using the novel object recognition (NOR) test. We found that 20 Gy but not lower doses abrogated the rats’ ability to recognize novel objects, a key test of memory. Importantly we showed in a follow-up study that a 4-week infusion of plerixafor started immediately after irradiation (with the same dosing and schedule as our earlier tumor studies) not only did not affect memory in the controls and 15 Gy WBI groups but completely protected against memory loss in the 20 Gy group. In conclusion we showed that blocking the CXCL12/CXCR4 pathway not only potentiates the radiation response of a breast cancer brain metastasis model in mice but also protects against radiation-induced cognitive dysfunction in rats. This has led us to propose that blocking of this pathway which prevents the radiation-induced influx of TAMs into tumors and normal tissues is a novel strategy to enhance the therapeutic ratio of radiotherapy (3). 1. Kioi M, Vogel H, Schultz G, Hoffman RM, Harsh GR, Brown JM. Inhibition of vasculogenesis, but not angiogenesis, prevents the recurrence of glioblastoma after irradiation in mice. J Clin Invest 2010; 120:694-705. 2. Liu SC, Alomran R, Chernikova SB, Lartey F, Stafford J, Jang T, et al. Blockade of SDF-1 after irradiation inhibits tumor recurrences of autochthonous brain tumors in rats. Neuro Oncol 2014; 16:21-8. 3. Brown JM, Thomas R, Nagpal S, Recht L. Macrophage exclusion after radiation therapy (MERT): A new and effective way to increase the therapeutic ratio of radiotherapy. Radiother Oncol 2019; 144:159-64. Citation Format: Martin Brown, Mehrdad Shamloo, Sophia Chernikova, Lawrence Recht. Blocking the CXCL12/CXCR4 pathway both radiosensitizes brain metastases in mice and protects against radiation-induced cognitive dysfunction following whole brain irradiation in rats [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PO-096.

142 Transcriptome Analysis Captures Radiation Exposure in a Dose-sensitive Manner and Predicts Short-term Survival in a Mouse Model

Abstract Introduction A mass exposure to irradiation would be a challenge to health care systems. A simple tool or test that indicates the intensity of the absorbed radiation or the chances of survivability would be invaluable in this scenario. To identify biomarkers that potentially could provide novel biodosimetry tools, we have conducted a radiation dose-response and time-course experiment in mice that includes an assessment of the transcriptome of the skin. Methods Groups of mice (n=5) received whole-body X-ray exposures (0, 1, 3, 6, or 20Gy) and skin biopsies were obtained from each animal at times post-irradiation (h2, Days 4, 7, 21, 28). Biopsies were collected from the 20Gy cohort for only days 0, 4, and 7. Total RNA was isolated and microarrays were performed and analyzed using custom R scripts to obtain lists of probe sets differentially expressed. Changes in gene expression at Benjamini-Hochberg FDR adjusted P &amp;lt; 0.05 and FC &amp;gt;2 were deemed significant. Analyses were performed comparing the different doses of X-ray exposure over all time points. Results Mice in the 20Gy group were euthanized by d7 and the dose was considered lethal. Animals in 1, 3, and 6Gy groups completed the full experiment to d28. Sammon plot analysis of transcriptomes showed clear separation of samples based on the irradiation levels and time after exposure. The clearest separation was between samples of lethal and sublethal doses. Samples from animals exposed to sublethal doses separated more based on timepoints rather than the IR dose suggesting a level of similarity in the progression of the response to sublethal doses. Downregulation was the dominant modulation in the significantly differentially transcribed genes (SDTGs) in the 20Gy group. Temporal changes in ratios of upregulated/downregulated SDTGs (P &amp;lt; 0.05 and FC &amp;gt; 2) revealed further the difference between of transcriptome responses after exposure to lethal and sublethal doses and indicated a delayed peaks response with increasing IR doses within the sublethal range. About 59% of the SDTGs in 20gy were common to all timepoints while no more than 11% were common at the same duration in the other groups. Ratios of the number of SDTGs at h2 to those common to all TPs decreased in a dose-dependent manner with potential radiation dosimetric applications. Conclusions These results demonstrate a solid ability in detecting IR exposure, differentiating lethal and sublethal exposures, and differentiating among the exposure to sublethal doses.

Impact of Radiation Dose on Postoperative Complications in Esophageal and Gastroesophageal Junction Cancers.

Introduction: The impact of radiation prescription dose on postoperative complications during standard of care trimodality therapy for operable stage II-III esophageal and gastroesophageal junction cancers has not been established.Methods: We retrospectively reviewed 82 patients with esophageal or gastroesophageal junction cancers treated between 2004 and 2016 with neoadjuvant chemoradiation followed by resection at a single institution. Post-operative complications within 30 days were reviewed and scored using the Comprehensive Complication Index (CCI). Results were compared between patients treated with <50 Gy and ≥ 50 Gy, as well as to published CROSS study neoadjuvant chemoradiation group data (41.4 Gy).Results: Twenty-nine patients were treated with <50 Gy (range 39.6–46.8 Gy) and 53 patients were treated with ≥ 50 Gy (range 50.0–52.5 Gy) delivered using IMRT/VMAT (41%), 3D-CRT (46%), or tomotherapy IMRT (12%). Complication rates and CCI scores between our <50 Gy and ≥ 50 Gy groups were not significantly different. Assuming a normal distribution of the CROSS data, there was no significant difference in CCI scores between the CROSS study neoadjuvant chemoradiation, <50 Gy, or ≥ 50 Gy groups. Rates of pulmonary complications were greater in the CROSS group (50%) than our <50 Gy (38%) or ≥ 50 Gy (30%) groups.Conclusions: In selected esophageal and gastroesophageal junction cancer patients, radiation doses ≥ 50 Gy do not appear to increase 30 day post-operative complication rates. These findings suggest that the use of definitive doses of radiotherapy (50–50.4 Gy) in the neoadjuvant setting may not increase post-operative complications.

Loosening Neuro-Optic Structures Dosimetric Constraints Provides High 5-Year LocalRecurrence-FreeSurvival With Acceptable Toxicity in T4 Nasopharyngeal Carcinoma Patients Treated With Intensity-Modulated Radiotherapy.

ObjectiveWhether the original dosimetric constraints of neuro-optic structures (NOS) are appropriate for patients with nasopharyngeal carcinoma (NPC) undergoing intensity-modulated radiotherapy (IMRT) remains controversial. The present study compared the survival rates and radiation-induced optic neuropathy (RION) occurrence between T4 NPC patients whose NOS were irradiated with a near maximum dose received by 2% of the volume (D2%) >55 Gy and ≤55 Gy. Moreover, the NOS dosimetric parameters and their correlation with RION occurrence were also evaluated.MethodsIn this retrospective study, 256 T4 NPC patients treated with IMRT between May 2009 and December 2013 were included. Patient characteristics, survival rates, dosimetric parameters, and RION incidence were compared between the D2% ≤55 Gy and D2% >55 Gy groups.ResultsThe median follow-up durations were 87 and 83 months for patients in the D2% >55 Gy and D2% ≤55 Gy groups, respectively. The 5-year local recurrence-free survival rates were 92.0 and 84.0% in the D2% >55 Gy and D2% ≤55 Gy groups (P = 0.043), respectively. There was no significant difference in the 5-year overall survival (OS) between both groups (D2% >55 Gy, 81.6%; D2% ≤55 Gy, 79.4%; P = 0.586). No patients developed severe RION (Grades 3–5), and there was no significant difference (P = 0.958) in the incidence of RION between the two groups. The maximum dose of NOS significantly affected the RION incidence, with a cutoff point of 70.77 Gy.ConclusionAppropriately loosening NOS dosimetric constraints in order to ensure a more sufficient dose to the target volume can provide a better 5-year local recurrence-free survival and acceptable neuro-optic toxicity in T4 NPC patients undergoing IMRT.

Impacts of ionization radiation on the cuticular hydrocarbon profile and mating success of male house crickets (Acheta domesticus)

Purpose Ionizing radiation is well known to have drastic impacts on major life history features including survivorship, growth, fertility, and longevity. What is much less appreciated is how radiation stress can cause changes to more subtle traits, such as those associated with sexual signaling, an underappreciated but vital aspect of insect reproduction. In the House Cricket (Acheta domesticus) cuticular hydrocarbons are vital for sex and species recognition, as well as a possible indicator of stress, making them crucial for successful mating and reproduction. Materials and methods Here, we analyze the impacts of ionizing radiation on the cuticular hydrocarbons of male crickets and its subsequent impacts on mating success. We exposed juvenile (14-day, 4th instar) male crickets to a broad range of radiation doses (2 Gy − 2 Gy). Results We detected significant changes in individual cuticular hydrocarbons across a broad range of doses in mature male crickets using gas-liquid chromatography. Specifically, dose was identified as a significant contributing factor to hydrocarbon increases p < .0001. Mating success was significantly reduced in 12 Gy (p < .0001), 10 Gy (0.0001), and 7 Gy (0.0060) groups compared to non-irradiated controls. Conclusion Insect chemical communication can be species specific, and functionally specialized. Here, we show that radiation can alter the chemical signals used to attract mates in a large bodied insect and this may be a contributing factor to the described reduction in male mating success. Further research should be conducted to further analyze the various modes of communication employed by male crickets to attract mates i.e. acoustic signaling, and how this may also contribute to the reduction in mating success seen in irradiated males.

LABORATORY EVALUATION OF BORIC ACID SUGAR BAITS AGAINST IRRADIATED AEDES AEGYPTI

The use of attractive toxic sugar baits (ATSBs) is a new paradigm in mosquito control. ATSBs kill both female and male mosquitoes attracted to sugar feed on a sugary solution containing a toxic substance such as boric acid. The impact of boric acid sugar baits on irradiated and non-irradiated Aedes aegypti was evaluated in the laboratory to determine any difference in mortality between the two groups. The mortality rates from the toxic sugar baits in both irradiated with 50 Gy and non-irradiated groups were highly significantly different, compared to those of corresponding control groups (t=6.916, p &lt;0.0001 and t=6.451, p&lt;0.01, respectively). Irradiated Ae. aegypti were not significantly different in mortality rates from non-irradiated counter parts after 24 and 48 h exposure to toxic sugar bait (t=0.576, p=0.578 and t=0.642, p=0.535 respectively). There was no significant difference in mortality caused by toxic sugar baits between the two sexes (t=0.595, p=0.869 and t=0.169, p=0.869 for irradiated and non-irradiated groups, respectively). The mean percent mortality after 48 h of exposure to toxic sugar baits was 43.3% for irradiated mosquitoes and 38.6% for non-irradiated mosquitoes. Mortality rates were significantly higher during second 24 h period in both irradiated and non-irradiated groups (t=-6.612, p&lt;0.01 and t=-5.278, p&lt;0.01 respectively). The study suggests that the toxic sugar bait approach could not be used within a sterile insect technique program to reduce the wild male population to increase the chances of wild females mating with irradiated males.

A rapid dynamic in vivo near-infrared fluorescence imaging assay to track lung vascular permeability after acute radiation injury.

To develop a dynamic in vivo near-infrared (NIR) fluorescence imaging assay to quantify sequential changes in lung vascular permeability-surface area product (PS) in rodents. Dynamic NIR imaging methods for determining lung vascular permeability-surface area product were developed and tested on non-irradiated and 13 Gy irradiated rats with/without treatment with lisinopril, a radiation mitigator. A physiologically-based pharmacokinetic (PBPK) model of indocyanine green (ICG) pulmonary disposition was applied to in vivo imaging data and PS was estimated. In vivo results were validated by five accepted assays: ex vivo perfused lung imaging, endothelial filtration coefficient (Kf) measurement, pulmonary vascular resistance measurement, Evan's blue dye uptake, and histopathology. A PBPK model-derived measure of lung vascular permeability-surface area product increased from 2.60 ± 0.40 [CL: 2.42-2.78] mL/min in the non-irradiated group to 6.94 ± 8.25 [CL: 3.56-10.31] mL/min in 13 Gy group after 42 days. Lisinopril treatment lowered PS in the 13 Gy group to 4.76 ± 6.17 [CL: 2.12-7.40] mL/min. A much higher up to 5× change in PS values was observed in rats exhibiting severe radiation injury. Ex vivo Kf (mL/min/cm H2O/g dry lung weight), a measure of pulmonary vascular permeability, showed similar trends in lungs of irradiated rats (0.164 ± 0.081 [CL: 0.11-0.22]) as compared to non-irradiated controls (0.022 ± 0.003 [CL: 0.019-0.025]), with reduction to 0.070 ± 0.035 [CL: 0.045-0.096] for irradiated rats treated with lisinopril. Similar trends were observed for ex vivo pulmonary vascular resistance, Evan's blue uptake, and histopathology. Our results suggest that whole body dynamic NIR fluorescence imaging can replace current assays, which are all terminal. The imaging accurately tracks changes in PS and changes in lung interstitial transport in vivo in response to radiation injury.

Moderate radioprotective role of zeolite in rats

Background/Aim. Exposure of living organisms to ?-radiation results in the overproduction of free radicals. The aim of the study was to test if the subacute administration of micronized zeolite (MZC) accomplishes radioprotective role based on the evaluation of the status of oxidative stress (OS) in the brain and 8-hydroxyguanosine (8-OH-dG) in the plasma of the rats exposed to the single ?-ray irradiation of 2 and/or 10 Gray (Gy). Methods. Wistar rats were on a four-week normal or 5% MZC supplemented diet and afterward exposed to the single ?-ray irradiation of 2 and 10 Gy. Groups of rats were: a) on a normal diet (the control group, and 2Gy and 10Gy groups); b) on 5% MZC supplemented diet (the control group ? MZC, MZC + 2Gy, and MZC + 10Gy groups). We measured malondialdehyde (MDA), glutathione (GSH) total, and activity of total super-oxide dismutase (tSOD) and manganese superoxide dismutase (MnSOD) in vulnerable brain regions (cerebellum, hippocampus, and cerebral cortex) and 8-OH-dG in plasma. Results. Lower MDA was found in the MZC+2Gy and MZC+10Gy groups compared to the 2Gy and 10Gy groups. Activity od total SOD was higher in the MZC+10Gy group than in the 10Gy one. GSH was the highest in the 10Gy group. Compared to the control group, 8-OH-dG was extremely higher in groups radiated with 10 Gy regardless of a diet, but slightly lower in the MZC+2Gy and 2Gy groups. Conclusion. Subacute MZC pretreatment accomplished partial radioprotective effect in irradiated rats compared to non-irradiated rats, based on suppressed SOD activity at 2 Gy, and reduced brain MDA when exposed to 2 Gy and 10 Gy.

Comparison of irradiated and non-irradiated acellular dermal matrices in breast reconstruction under radiotherapy.

BackgroundAcellular dermal matrices (ADMs) have become an essential material for implant-based breast reconstruction. No previous studies have evaluated the effects of sterility of ADM under conditions of radiation. This study compared sterile (irradiated) and aseptic (non-irradiated) ADMs to determine which would better endure radiotherapy.MethodsEighteen male Balb/C mice were assigned to the control group with no irradiation (group 1) or one of two other groups with a radiation intensity of 10 Gy (group 2) or 20 Gy (group 3). Both sterile and aseptic ADMs were inserted into the back of each mouse. The residual volume of the ADM (measured using three-dimensional photography), cell incorporation, α-smooth muscle actin expression, and connective tissue growth factor expression were evaluated. The thickness and CD3 expression of the skin were measured 4 and 8 weeks after radiation.ResultsIn groups 2 and 3, irradiated ADMs had a significantly larger residual volume than the non-irradiated ADMs after 8 weeks (P<0.05). No significant differences were found in cell incorporation and the amount of fibrosis between irradiated and non-irradiated ADMs. The skin was significantly thicker in the non-irradiated ADMs than in the irradiated ADMs in group 3 (P<0.05). CD3 staining showed significantly fewer inflammatory cells in the skin of irradiated ADMs than in non-irradiated ADMs in all three groups after 4 and 8 weeks (P<0.05).ConclusionsUnder radiation exposure, irradiated ADMs were more durable, with less volume decrease and less deposition of collagen fibers and inflammatory reactions in the skin than in non-irradiated ADMs.

Fractionated stereotactic radiosurgery in treating the complex intracranial arteriovenous malformations

Background: The aim of this study was to examine the efficacy and safety of treating large or eloquently located intracranial arteriovenous malformations (AVMs) with fractionated stereotactic radiosurgery (FSRS).Materials and Methods: Eighteen patients with AVM treated with FSRS between March 2006 and August 2018 were retrospectively evaluated. The nidus obliteration, volume reduction, rate of rebleeding, newly onset neurological deficit, and signal change in magnetic resonance imaging (MRI) were evaluated.Results: With a median follow-up of 88 months (range: 24–154), 6 of the 18 lesions (33.3%) had a complete obliteration. All obliteration occurred in patients received the total treatment dose of 21 Gy (6 of 9 patients, 66.7%). The median time to complete obliteration was 38 months (range: 12–53). The mean volume reduction after FSRS in the 25 Gy group was 30.2% ± 20.9% and that in the 21 Gy group was 87.7% ± 24.2%. During the follow-up period, 4 of 18 (22.2%) lesions revealed T2 signal change in the MRI. No FSRS-related complication was noted clinically or radiologically.Conclusion: According to the present results, FSRS could be an effective and safe treatment alternative for complicated AVMs. Delayed toxicity after treatment is not noticed in the current study, but long-term follow-up is required. A higher dose in total and each fraction is likely needed when treating larger lesions.

Establishment of an in vitro model using the rat alveolar macrophage cell line NR8383.

To establish an in vitro model of radiation-induced lung injury using rat lung alveolar macrophages (NR8383). Using a medical electronic linear accelerator, cells were irradiated with either 0 Gy or 6 Gy X-rays. At 6, 12, 24, 30 and 48 h, the DNA damage index (8-OHdG) and lipid damage index (MDA) were measured in the two groups. We also determined the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and transforming growth factor-β (TGF-β). The levels of 8-OHdG and MDA in the 6 Gy irradiation group were higher than those in the 0 Gy group at 6, 12, 24, 30 and 48 h after irradiation. The levels reached the highest value -6 h after irradiation, and then gradually decreased. The levels of the inflammatory factors TNF-α, TGF-β and IL-6 were higher in the 6 Gy irradiation group than those in the 0 Gy group at 6, 12, 24, 30 and 48 h after irradiation. Six Gy X-ray irradiated NR8383 cells can be used to establish an in-vitro model of radiation-induced lung injury. The levels of 8-OHdG, MDA, TNF-α, TGF-β and IL-6 can be used as effective evaluation indicators.

Dose-Response Relationship in Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma: A Pooled Analysis of an Asian Liver Radiation Therapy Group Study

Despite the worldwide implementation of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC), there is a lack of consensus guideline on prescription dose. Herein, this multinational study aimed to investigate the effects of the prescribed radiation dose on oncologic outcomes of SBRT for HCC. The multi-institutional retrospective cohort included 510 patients treated with SBRT between 2010 and 2016. All relevant clinical factors and factors related to SBRT were analyzed to evaluate freedom from local progression (FFLP) and overall survival (OS). Based on a biologically effective dose (BED) cutoff value of 100 Gy, 198 tumors were selected from each group in propensity score matching (PSM). Baseline characteristics in the BED <100 Gy group were unfavorable (Child-Pugh class B, 19%; advanced stage, 72%; median tumor size was 4 cm) compared with the BED ≥100 Gy group. With a median follow-up of 22 (interquartile range, 9.8-37.6) months, the 2-year FFLP and OS rates were 77% and 73%, respectively. Patients treated with a BED ≥100 Gy showed better rates of 2-year FFLP and OS than patients treated with a BED <100 Gy (FFLP, 89% vs 69%; OS, 80% vs 67%; P < .001). In the multivariable analysis before and after PSM, BED ≥100 Gy was identified as the main prognostic factor for both FFLP and OS (P < .01). Additionally, a dose-response relationship was observed between FFLP and BED (odds ratio, 0.92 per 5 Gy, P = .048). A BED ≥100 Gy was significantly associated with outcomes, and a dose-response relationship was observed between local tumor progression and BED. Given that SBRT is being increasingly used in HCC, detailed consensus guidelines regarding SBRT dose prescription should be established.

The Radio-Sensitivity Effects of Human Umbilical Cord Wharton’s Jelly Mesenchymal Stem Cell’s Conditional Medium on MDA-MB-231 Cells

Background: While radiotherapy is the important modality in the treatment of breast cancer cells, radioresistance of some tumor cell lines such as MDA-MB-231 is still a limitation that must be considered. Objectives: The present study was done to examine the effect of the conditioned medium of the human umbilical cord Wharton's jelly stem cells (hWJSCs + CM) on the radiosensitivity of MDA-MB-231 cells in combination with megavoltage-radiations. Methods: Groups are Control, CM, GY, and GY + CM. In irradiation groups, breast cancer cells were exposured with 4, 6, and 8 Gy radiation. Each group includes different doses of the conditioned medium of hWJSCs (25%, 50%, and 75%). Results: The MTT assay showed that the proliferative activity of Gy + CM groups at all doses of condition medium decreased significantly compared with the control, rather than Gy groups. Trypan blue viability test showed that the survival rate of MDA-MB-231 cells significantly reduced in the CM and 8 Gy + CM groups compared with the control group, rather than Gy groups. MDA-MB-231 cells lost their normal spindle shape and became thinner and longer after 48h of treatment and the number of cells sharply reduced in Gy + CM groups compared with the control group, rather than Gy groups. These changes were accompanied by inducing significant up-regulation of Interleukin-6 (IL-6) in the 4 Gy + CM and 8 Gy + CM groups compared with the control group, rather than Gy groups and as a consequence, a decrease in the amount of transmembrane tumor necrosis factor-α (tmTNF-α) as a pro-inflammatory cytokine in the Gy + CM groups compared with the control group, rather than Gy groups. Also, we indicated that the radiosensitivity of breast cancer cells was probably enhanced by an increase in different doses of the conditioned medium of stem cells. Conclusions: Treatment of the MDA-MB-231 cells with hWJSCs + CM plus radiotherapy inhibited the growth and proliferation of cancer cells and this method is a novel strategy for breast cancer therapy by overcoming radioresistance.

Effects of fractionation and ionizing radiation dose on the chemical composition and microhardness of enamel

ObjectiveTo evaluate the chemical and mechanical properties of enamel submitted to different in vitro radiation protocols. DesignThird molars were divided into seven groups (n = 8): non-irradiated (NI); a single dose of 30 Gy (SD30), 50 Gy (SD50), or 70 Gy (SD70) of radiation; or fractional radiation doses of up to 30 Gy (FD30), 50 Gy (FD50), or 70 Gy (FD70). Hemisections were analysed by Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS) and Knoop microhardness (KHN) test. One-way ANOVA followed by Bonferroni's post-hoc test compared the test groups with the NI. Two-way ANOVA was performed for the fractionation and radiation dose, followed by Bonferroni’s test (α = 0.05). ResultsFTIR revealed differences for the amide I band between the NI and FD50 and NI and FD70 groups (p < 0.001). For the organic matrix/mineral ratio, the FD70 group presented a lower ratio compared to NI (p = 0.009). Excluding the NI group, there were differences between the FD30 and FD50 (p = 0.045) and the FD30 and FD70 groups (p < 0.001). For EDS, there were differences for Ca (p = 0.011) and Ca/P (p < 0.001), with the FD70 group presenting lower values compared to NI (p = 0.015; p < 0.001). For KHN, the FD70 group presented lower values than the NI (p = 0.002). Two-way ANOVA showed difference for the dose (p < 0.001), with the 70 Gy group presenting a lower KHN value within the fractionated groups. ConclusionFractional doses 70 Gy irradiation caused chemical and mechanical changes to enamel. Radiation applied in single or fractional doses produced different effects to enamel.

The Impact of Ablative Doses on Survival for Patients Treated with Definitive Radiotherapy for Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (IHCC) is a rare malignancy with a rising incidence. Prognosis is poor, especially for patients who are surgically inoperable. A recent single institution retrospective study demonstrated improved local control and overall survival for patients treated with biologically effective dose (BED)>80.5 Gy, compared to those with BED ≤80.5 Gy. The purpose of this study is to investigate the impact of ablative radiotherapy doses on survival using a large cancer database registry. The National Cancer Database was queried (2004-2015) for patients with histologically-confirmed, localized IHCC treated with definitive external beam radiotherapy with or without chemotherapy. Patients treated with palliative radiotherapy dose fractionation schemes were excluded (BED <40). Patients were divided into two cohorts based on BED: BED>80.5 Gy and BED ≤80.5 Gy. Kaplan-Meier analysis evaluated overall survival (OS). Significance of Kaplan-Meier estimates of OS was determined by log-rank testing. Multivariable Cox Proportional Hazards Regression Analysis (coxph) was used to establish factors associated with OS, with BED as a continuous variable. A total of 579 patients met the inclusion criteria; median BED was 60 Gy. 481 (83%) of patients received BED ≤80.5 Gy, whereas 98 (17%) received BED >80.5 Gy. Median follow-up was 11.8 and 13.8 months for the BED ≤80.5 Gy and BED>80.5 Gy groups, respectively. Median OS was 12.5 months for the BED ≤80.5 Gy group and 14.65 months for the BED>80.5 Gy groups (log-rank p = 0.035). Coxph results can be found in Table 1. Older age, more advanced T and N stage, and lower BED as a continuous variable were significantly associated with worse OS (p<0.05 for all). Sex, presence of comorbidities and the receipt of chemotherapy were not significantly with OS. This is the largest study to do date looking at the effect of dose escalation on outcomes of definitive radiotherapy for patients treated for IHCC. Higher BED was significantly associated with better OS using both Kaplan Meier (BED ≤80.5 Gy verses BED>80.5 Gy) and as a continuous variable on coxph. Chemotherapy was not significantly associated with OS. The retrospective nature of this analysis is recognized as a limitation. Further prospective studies are warranted to confirm these findings.Abstract 3516; TableMultivariable Cox Proportional Hazards Regression Analysis ResultsHazard Ratio95% CIp-valueAge1.0151.007-1.023<0.0005Sex0.9020.750-1.0840.2713BED0.9940.990-0.9990.0108T stage1.1421.035-1.2600.0083N stage1.4601.193-1.7860.0002Chemotherapy0.8720.701-1.0850.2204No comorbidities1.0360.8445-1.2710.7355 Open table in a new tab

Are Doses of Radiation to the Cardiovascular Adipose Tissue Significant for Survival in Patients with Non-Small Cell Lung Cancer?

Adipose tissue surrounding the heart is important in heart physiology and pathogenesis of cardiovascular diseases, has not been studied for damage from radiotherapy. We hypothesize that doses of radiation to the different parts of adipose tissue around the heart are important for heart damage, which are thus associated with survival in patients treated with thoracic radiation for non-small cell lung cancer (NSCLC). This is a secondary analysis of patients enrolled in prospective studies treated with definitive radiotherapy. The patients of I∼III stages treated with SBRT or IMRT (doses range from 50Gy to 85Gy) were included. Heart and pericardium were contoured consistently according to the RTOG1106 Atlas. Quantification of adipose tissue was semi-automatic contouring with CT imaging. Adipose tissue structures were defined and contoured according to the following three parts: Epicardial adipose tissue (EAT), paracardial adipose tissue (PAT) and post-mediastinal adipose tissue (pMAT). EAT is epicardial fat defined as adipose tissue surrounding the heart, located between the myocardium and the visceral pericardium. PAT is adipose tissue located external to the parietal pericardium, while pMAT refers to the fat tissue in posterior mediastinum. Clinical factors and dose-volume parameters associated with overall survival (OS) were identified via Cox proportional hazards model using SPSS 17.0 software. R (Version 3.6.2) was used to determine the optimal cut-off values of continuous variable. Log-rank tests were then performed using the cut-off splits for each variable. Mean dose of EAT was 16.3Gy (range 0.4-47.4), PAT was 19.9Gy (range 2.03-40.41), and pMAT was 15.0 Gy (range 0.9-56.4). Median follow-up time was 44.2 months, the median OS was 41.7 months, and 3-year OS rate was 52.8% (95% CI 37.9-67.7). Under univariate analysis, a trend of association was observed between OS and PAT, significant better OS in patients mean dose of PAT <18.3 Gy (HR 2.490, 95%CI 0.969-6.402, p = 0.058). There was no significant effect in OS for mean dose of EAT (p = 0.252) and pMAT (p = 0.103). Under multivariable analysis, mean doses of PAT and pMAT were significantly associated with OS (HR 3.835, 95%CI 1.237-11.895, p = 0.020; HR 2.511, 95%CI 1.014-6.216, p = 0.046, respectively), while mean doses of EAT, conventional heart and pericardium were not. Log-rank tests showed PAT<18.3 Gy group had a better OS than PAT≥18.3 Gy group (p = 0.05). This is the first study examine the effect of adipose tissue, revealing that the mean doses of PAT and pMAT were significantly associated with OS in this study of limited number of patients. This finding suggests the potential significance of radiation damage to the paracardial region of adipose tissue and demands future prospective study.

Reduced Left Ventricular Myocardial Blood Flow After Radiation Therapy For Thoracic Esophagus Cancer: A Study Using Stress Dynamic Perfusion CT

Radiation therapy (RT) has greatly contributed to improving the prognosis of cancer in the thoracic region. As treatment outcomes improve, myocardial disorders induced by RT have become a serious problem. To investigate myocardial disorder after RT for esophageal cancer using myocardial stress dynamic computed tomography perfusion (CTP) before and after RT. Fifteen patients with esophageal cancer scheduled for RT were prospectively enrolled between January 2017 and January 2019. CTP was performed before and 3 months after RT to investigate the relationship between changes in hyperemic myocardial blood flow (hMBF) and the radiation dose for the left ventricle (LV). Fifteen segments of LV myocardium were classified into 3 groups according to radiation dose: <20 Gy (Group A), 20–40 Gy (Group B) and >40 Gy (Group C), by fusing CT angiography (CTA) onto radiation planning CT images. Twelve of 15 patients completed CTP before and at a median of 2.8±1.34 months after RT. A total of 180 LV segments (Group A, n = 122; B, n = 39; and C, n = 19) was analyzed. Groups B (pre-RT 147.5 ± 27.7 mL/min/100g vs post-RT 135.5 ± 25.4 mL/min/100g, p = 0.035) and C(pre-RT 146.3 ± 27.0 mL/min/100g vs post-RT 126.0 ± 16.0 mL/min/100g, p = 0.022) showed significant reduction in hMBF, while there was no significant difference in hMBF for Group A between pre- and post-RT (145.3 ± 26.3 mL/min/100g vs 146.4 ± 19.3 mL/min/100g, p = 0.729). There was a significant difference in ΔhMBF between Groups A and B (1 ± 27.5 mL/min/100g vs -12 ± 33.9 mL/min/100g, p = 0.014). Significant negative correlation was found between the LV radiation dose and change in hMBF (r = -0.263, p = 0.004). Significant reduction in hMBF was observed with CTP taken approximately 3 months after RT in the LV segments for which radiation dose ≥20 Gy was administered. The alteration in hMBF was related to LV radiation dose. These findings should increase our knowledge of ionizing radiation injury to the heart, and provide important insights for RT planning optimization to prevent or mitigate the adverse effects.

Tumour control probability of a UK cohort of lung SABR patients

AbstractAims:The aim of this work is to report on the tumour control probability (TCP) of a UK cohort of lung stereotactic ablative radiotherapy patients (n = 198) for a range of dose and fractionations common in the UK.Materials and methods:TCP values for 3 (54 Gy), 5 (55 and 60 Gy) and 8 (50 Gy) fraction (#) schemes were calculated with the linear-quadratic Marsden TCP model using the Biosuite software.Results:TCP values of 100% were computed for the 3 # and for 5 # (α/β = 10 Gy) cohorts; reduced to 99% (range 97–100) for the 5 # cohort only when an α/β of 20 Gy was used. The average TCP value for the 50 Gy in 8 # regime was 97% (range 92–99, α/β = 10 Gy) and 64% (range 48–79, α/β = 20 Gy). Statistical significant differences were observed between the α/β of 10 Gy versus 20 Gy groups and between all data grouped by fraction.Conclusion:TCPs achievable with current planning techniques in the UK have been presented. The ultra-conservative 50 Gy in 8 # scheme returns a significantly lower TCP than the other regimes.