Results Of Radiotherapy Research Articles

159 Outcomes of thoracic radiotherapy for oligoprogression after a response to Pembrolizumab in patients with advanced Non-Small Cell Lung Cancer

159 Outcomes of thoracic radiotherapy for oligoprogression after a response to Pembrolizumab in patients with advanced Non-Small Cell Lung Cancer

Protective Effect of Pre-Radiotherapy Polyphenol and Bioflavonoid Application on Free Radical Levels in Rat Periodontal Tissue and Buccal Mucosa

Aim: This study aimed to assess the impact of therapeutic radiation on free radical levels in rat periodontal tissue and cheek mucosa and investigate the protective effect of pre-radiotherapy application of polyphenols and bioflavonoids (ENOANT®).
 Material and Method: Forty rats were divided into four groups, receiving various ENOANT® regimens before therapeutic radiation. Free radical levels were evaluated using MDA and sialic acid measurements.
 Results: The study found no significant difference in free radical formation among rats subjected to therapeutic dose radiation. Long-term ENOANT® use prior to radiotherapy led to a significant decrease in tissue free radical levels compared to the radiotherapy-only group.
 Conclusion: Pre-radiotherapy administration of ENOANT® demonstrated a protective effect against radiation-induced oxidative stress in rat periodontal tissue and buccal mucosa. These findings suggest ENOANT® as a promising intervention to enhance radiotherapy outcomes.

Integrated pretreatment diffusion kurtosis imaging and serum squamous cell carcinoma antigen levels: a biomarker strategy for early assessment of radiotherapy outcomes in cervical cancer.

This study aims to explore the utility of pretreatment DKI parameters and serum SCC-Ag in evaluating the early therapeutic response of cervical cancer to radiotherapy. A total of 33 patients diagnosed with cervical cancer, including 31 cases of cervical squamous cell carcinoma and two cases of adenosquamous carcinoma, participated in the study. All patients underwent conventional MRI and DKI scans on a 3T magnetic resonance scanner before radiotherapy and after ten sessions of radiotherapy. The therapeutic response was evaluated based on the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Patients were categorized into a response group (RG), comprising Complete Remission (CR) and Partial Remission (PR), and a non-response group (NRG), comprising Stable Disease (SD) and Progressive Disease (PD). LASSO was employed to select pretreatment DKI parameters, and ROC curves were generated for the selected parameters and serum SCC-Ag. Significant differences were observed in pretreatment MD, Da, Dr, MK, Ka, Kr, and SCC-Ag between the RG and NRG groups (P < 0.01). However, no significant differences were noted for FA and FAK (P = 0.441&0.928). The two selected parameters (MD and MK) demonstrated area under the curve (AUC), sensitivity, and specificity of 0.810, 0.769, 0.850 and 0.827, 0.846, 0.750, respectively. The combination of MD and MK exhibited an improved AUC of 0.901, sensitivity of 0.692, and specificity of 1.000, with a higher Youden index compared to the individual parameters. Conversely, the AUC, sensitivity, and specificity of the combination of MD, MK, and SCC-Ag were 0.852, 0.615, and 1.000, with a Youden index of 0.615. Pretreatment MD, MK, and SCC-Ag demonstrate potential clinical utility, with the combined application of MD and MK showing enhanced efficacy in assessing the early therapeutic response of cervical cancer to radiotherapy. The addition of SCC-Ag did not contribute further to the assessment efficacy.

Comparison of the Outcome of Surgery and Radiotherapy in the Treatment of Early Carcinoma of the Larynx

Background: The most prevalent disease to afflict the head and neck region is laryngeal cancer. The early stage of this disease, T1T2N0M0, has a higher chance of recovery than the other phases. Radiation therapy and surgery are its therapeutic techniques.&#x0D; Objective: To Compare the outcome of surgery and radiotherapy in the treatment of early carcinoma of the larynx&#x0D; Methods: This cross-sectional study was carried out at tertiary hospital Dhaka from January 2022 to January 2023. Where A total of 200 Patients of carcinoma of the larynx are evaluated properly by detailed history taking, clinical examination and relevant investigation. During the study two groups of patients were dealt separately; Group-1: Surgery using LASER, n=100 and Group-2: radiotherapy, n=200. All the patients were followed up after 2 weeks, 1 month and then three monthly for one year.&#x0D; Results: During the study, supraglottis carcinoma was found in 65% of radiotherapy group and 70% in surgery group, glottic carcinoma was 35% &amp; 30%, respectively in radiotherapy and surgery group. No case found with subglottic carcinoma. Where in surgery group 7% patients had haematoma, 5% patients had seroma &amp; pharyngeal stenosis. In radiotherapy group 2.5% Severe radiation necrosis of skin &amp; 3% had Respiratory distress following radiotherapy. . In the radiotherapy group, 25% cases were scored as normal and 45% as good. For the surgery group, 40% patients had good voice and speech, 35%r had moderate voice and speech, and 5% had poor voice and speech. This difference was statistically significant (p=.001). 14% of the irradiation group had a primary site recurrence compared with 20% in the surgery group at 12th months. There was a significant difference in the pattern of recurrence in the neck between the two treatment groups. Only 5% of those who were treated with irradiation had a recurrence in the neck. 14% of patients in the surgery group had a recurrence in the neck; this difference was statistically significant.&#x0D; Conclusions: When treating early laryngeal cancer, radiation therapy and surgery are equally successful. However, patients who had radiation therapy had much improved speech and voice quality compared to those who received surgery.

Abstract 567: Fisetin sensitizes triple negative breast cancer cells to radiation

Abstract Triple negative breast cancer (TNBC) represents a highly aggressive subtype, constituting approximately 20% of all breast cancer cases. Y-box binding protein-1 (YB-1) is often overexpressed in various tumor types and has been implicated in conferring resistance to cell death induced by radiotherapy. Fisetin, a flavonoid compound with demonstrated anti-cancer properties, operates in part through inhibiting phosphorylation of YB-1 by p90 ribosomal S6 kinase (RSK). In this study, we investigated the potential synergistic effects of combining fisetin with radiotherapy in TNBC. The activation status of the RSK signaling pathway was assessed in both total cell lysate and subcellular fractions using Western blotting. A standard clonogenic assay was employed to evaluate post-irradiation cell survival. To investigate the frequency of double-strand breaks (DSBs) and chromosomal aberrations, γH2AX foci assay and 3-color fluorescence in situ hybridization analyses were conducted, respectively. The DSB repair pathways targeted by fisetin were examined in cells expressing genomically integrated reporter constructs by quantifying green fluorescence protein expression through flow cytometry. Apoptosis and autophagy were measured using flow cytometric quantification of sub-G1 cells and the assessment of LC3-II protein expression, respectively. Kinase array and phosphoproteomics analyses were carried out to study the potential impact of fisetin on the signaling involved in the DNA damage response (DDR) after irradiation. We demonstrated that fisetin mimics the effects of RSK pharmacological inhibitors in terms of effect on YB-1 phosphorylation. Treatment with fisetin increased frequency of DSB in non-irradiated cells and impaired repair of DSB after irradiation. Fisetin attenuated DSB repair by suppressing the classical non-homologous end-joining and homologous recombination repair pathways. The frequency of chromosomal aberration was enhanced by fisetin treatment. The effect of fisetin on inhibiting DSB repair was partially YB-1 dependent. Phosphoproteomic analysis revealed that fisetin inhibits DDR signaling, which leads to radiosensitization in TNBC cells, as shown in combination with single dose or fractionated doses irradiation. Fisetin neither inhibited DSB repair nor radiosensitized normal human fibroblast HSF7 cells. The radiosensitizing effect of fisetin was not attributed to enhancing apoptosis or modulating autophagy. In summary, combining fisetin with radiotherapy may enhance TNBC radiotherapy outcomes. -This research was supported by a grant from the German Research Council (DFG,TO 685/2-3). Citation Format: Shayan Khozooei, Soundaram Veerappan, Mahmoud Toulany. Fisetin sensitizes triple negative breast cancer cells to radiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 567.

Abstract 1282: Gavage with Candida albicans leads to fungal colonization of colorectal tumors and decreased response to radiotherapy

Abstract The host microbiome in the gut and tumors have been shown to affect tumor growth and therapeutic response in cancer. Furthermore, the presence of specific fungal taxa are associated with tumor hypoxia, tumor progression, therapeutic response, and clinical outcomes in colorectal cancer (CRC). Preliminary data from our group found that the presence of Candida species increased tumor hypoxia and decreased overall survival in CRC. However, whether intratumoral Candida drive, support, or simply inhabit tumors with poor prognoses remains unclear. Here, we investigate a casual role for Candida albicans in tumor progression and therapy response using a syngeneic mouse model of microsatellite-instability high (MSI-H) colorectal cancer. We subcutaneously implanted MC38 colorectal cancer cells into C57BL/6 mice and then orally gavaged these mice with C. albicans, Saccharomyces cerevisiae, or PBS. The site of tumor formation was locally irradiated once (7.5 Gy), and growth of the tumor was measured over time. Differences in tumor volume were assessed by longitudinal mixed-effect models. Tumor sections were stained for fungi using calcofluor white (CFW) and underwent bulk RNA sequencing to detect differential gene expression, which were interpreted using gene set enrichment analysis (GSEA). Mice gavaged with C. albicans showed decreased response to radiation compared to mice gavaged with either S. cerevisiae (p&amp;lt;0.05) or PBS (p&amp;lt;0.001). Additionally, hyphae were observed in murine tumors gavaged with C. albicans, suggesting translocation of gavaged C. albicans from the gut to tumors. Further, tumors from mice gavaged with C. albicans displayed unique gene expression profiles, including decreased interferon alpha and IL-6 and STAT3 signaling, decreased oxidative phosphorylation, and decreased apoptosis-related gene expression. Here, we show that C. albicans may confer resistance to radiation therapy and affects immune and cancer cell activity in the MC38 (MSI-H) syngeneic in vivo model of colorectal cancer. Further, we show that hyphal fungi can be visualized in heterotopic murine tumors from our C. albicans gavage condition. These data establish that fungi can translocate from the gut to distal tumor sites, and that upon translocation, changes in gene expression and therapy response are observed. Future directions will explore the mechanism by which these effects occur and whether these findings can be leveraged to improve radiotherapy outcomes. Citation Format: Dennis J. Grencewicz, Alexander Loncar, Rebecca Hoyd, Aaditya Pallerla, Nyelia Williams, Martin Benej, McKenzie Kreamer, Yogita Mehra, Shiva Jahanbakhshi, Matthew Anderson, Nicholas Denko, Daniel Spakowicz. Gavage with Candida albicans leads to fungal colonization of colorectal tumors and decreased response to radiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1282.

Temporal Considerations in Brain Metastases Radiation Therapy: The Intersection of Chronobiology and Patient Profiles.

The circadian system, a vital temporal regulator influencing physiological processes, has implications for cancer development and treatment response. Our study assessed circadian timing's impact on whole-brain radiotherapy outcomes in brain metastases for personalized cancer therapy insights. The aim of the study was to evaluate circadian influence on radiation treatment timing and its correlation with clinical outcomes and to identify patient populations benefiting from interventions synchronizing circadian rhythms, considering subgroup differences and potential disparities. An IRB-approved retrospective analysis of 237 patients undergoing whole-brain radiotherapy for brain metastases (2017-2021), receiving over 80% of treatments in the morning or afternoon, was performed. Survival analyses utilized Kaplan-Meier curves. This was a single-institution study involving patients receiving whole-brain radiotherapy. Demographic, disease, and socioeconomic parameters from electronic medical records were collected. Morning treatment (n = 158) showed a trend toward improved overall survival vs. afternoon (n = 79); the median survival was 158 vs. 79 days (p = 0.20, HR = 0.84, CI95% 0.84-0.91). Subgroup benefits for morning treatment in females (p = 0.04) and trends in controlled primary disease (p = 0.11) and breast cancer metastases (p = 0.08) were observed. Black patients exhibited diminished circadian influence. The present study emphasized chronobiological factors' relevance in brain metastases radiation therapy. Morning treatment correlated with improved survival, particularly in specific subgroups. Potential circadian influence disparities were identified, laying a foundation for personalized cancer therapy and interventions synchronizing circadian rhythms for enhanced treatment efficacy.

Modeling hypoxia-induced radiation resistance and the impact of radiation sources

Hypoxia contributes significantly to resistance in radiotherapy. Our research rigorously examines the influence of microvascular morphology on radiotherapy outcome, specifically focusing on how microvasculature shapes hypoxia within the microenvironment and affects resistance to a standard treatment regimen (30×2GyRBE). Our computational modeling extends to the effects of different radiation sources. For photons and protons, our analysis establishes a clear correlation between hypoxic volume distribution and treatment effectiveness, with vascular density and regularity playing a crucial role in treatment success. On the contrary, carbon ions exhibit distinct effectiveness, even in areas of intense hypoxia and poor vascularization. This finding points to the potential of carbon-based hadron therapy in overcoming hypoxia-induced resistance to RT. Considering that the spatial scale analyzed in this study is closely aligned with that of imaging data voxels, we also address the implications of these findings in a clinical context envisioning the possibility of detecting subvoxel hypoxia.

Impact of LKB1 status on radiation outcome in patients with stage III non-small-cell lung cancer

Preclinical studies suggest that loss of LKB1 expression renders cancer cells less responsive to radiation partly through NRF2-mediated upregulation of antioxidant enzymes protecting against radiation-induced DNA damage. Here we investigated the association of an alteration in this pathway with radio-resistance in lung cancer patients. Patients with locally advanced non-small cell lung cancer (LA-NSCLC) who were treated with chemoradiotherapy (CRT) and analyzed for LKB1 expression using semiquantitative immunohistochemistry. Clinical characteristics and expression of LKB1 were analyzed for association with radiotherapy outcomes. We analyzed 74 available tumor specimens from 178 patients. After a median follow-up of 40.7 months, 2-year cumulative incidence of locoregional recurrence (LRR) in patients who had LKB1Low expression was significantly higher than those with LKB1High expression (68.8% vs. 31.3%, P = 0.0001). LKB1Low expression was found significantly associated with a higher incidence of distant metastases (DM) (P = 0.0008), shorter disease-free survival (DFS) (P = 0.006), and worse overall survival (OS) (P = 0.02) compared to LKB1High expression. Moreover, patients with LKB1Low expression showed a significantly higher 2-year cumulative incidence of LRR (77.6% vs. 21%; P = 0.02), higher DM recurrence (P = 0.002), and shorter OS (P < 0.0001) compared with the EGFR-mutant group. For all patients with LKB1Low who had LRR, these recurrences occurred within the field of radiation, in contrast to those with LKB1High expression having both in-field, marginal, and out-of-field failures. LKB1 expression may serve as a potential biomarker for poor outcomes after receiving radiation in LA-NSCLC patients. Further studies to confirm the association and application are warranted.

Enhancing radiosensitivity in triple-negative breast cancer through targeting ELOB.

Enhancing radiotherapy sensitivity is crucial for improving treatment outcomes in triple-negative breast cancer (TNBC) patients. In this study, we investigated the potential of targeting Elongin B (ELOB) to enhance radiotherapy efficacy in TNBC. Analysis of TNBC patient cohorts revealed a significant association between high ELOB expression and poor prognosis in patients who received radiation therapy. Mechanistically, we found that ELOB plays a pivotal role in regulating mitochondrial function via modulating mitochondrial DNA expression and activities of respiratory chain complexes. Targeting ELOB effectively modulated mitochondrial function, leading to enhanced radiosensitivity in TNBC cells. Our findings highlight the importance of ELOB as a potential therapeutic target for improving radiotherapy outcomes in TNBC. Further exploration of ELOB's role in enhancing radiotherapy efficacy may provide valuable insights for developing novel treatment strategies for TNBC patients.

Five-year clinical outcomes of scanning carbon-ion radiotherapy for prostate cancer.

Carbon-ion radiotherapy (CIRT) has been associated with favorable clinical outcomes in patients with prostate cancer. At our facility, all patients are treated using scanning CIRT (sCIRT). We retrospectively analyzed five-year clinical outcomes of prostate cancer treated with sCIRT to investigate treatment efficacy and toxicity. In this study, we included 253 consecutive prostate cancer patients treated with sCIRT at the Kanagawa Cancer Center from December 2015 to December 2017. The total dose of sCIRT was set at 51.6 Gy (relative biological effect) in 12 fractions over three weeks. We employed the Phoenix definition for biochemical relapse. The overall survival (OS), biochemical relapse-free (bRF) rate, and cumulative incidence of late toxicity were estimated using the Kaplan-Meier method. Toxicity was assessed using the Common Terminology Criteria for Adverse Events version 4.0. The median age of the patients was 70 years (range: 47-86 years). The median follow-up duration was 61.1 months (range: 4.1-80.3 months). Eight (3.2%), 88 (34.8%), and 157 (62.1%) patients were in the low-risk, intermediate-risk, and high-risk groups, respectively, according to the D'Amico classification system. The five-year OS and bRF were 97.5% and 93.3%, respectively. The five-year bRF rates for the low-risk, intermediate-risk, and high-risk groups were 87.5%, 93.7%, and 93.4%, respectively (p = 0.7215). The five-year cumulative incidence of Grade 2 or more late genitourinary and gastrointestinal toxicity was 7.4% and 1.2%, respectively. The results of this study show that sCIRT has a favorable therapeutic effect and low toxicity in the treatment of prostate cancer.

169 Outcomes of Stereotactic Body Radiation Therapy for Re-Irradiation of Squamous Carcinomas of the Head and Neck

169 Outcomes of Stereotactic Body Radiation Therapy for Re-Irradiation of Squamous Carcinomas of the Head and Neck

132 (PB-132) Poster - Single center analysis of safety profile and survival outcomes of intracranial radiation therapy in combination with trastuzumab-emtansine (T-DM1)

132 (PB-132) Poster - Single center analysis of safety profile and survival outcomes of intracranial radiation therapy in combination with trastuzumab-emtansine (T-DM1)

The impact of multidisciplinary approaches on the outcomes of olfactory neuroblastoma treated with postoperative radiotherapy.

We investigated the outcomes of postoperative radiation therapy for olfactory neuroblastoma (ONB) and our cross-departmental collaboration to enhance the effectiveness of cancer treatment. We retrospectively evaluated 22 patients with ONB who underwent postoperative radiotherapy after tumor resection. En bloc resection was performed; pathology specimens were prepared in coronal sections; and irradiation fields were determined after discussion with radiation oncologists, head and neck surgeons, and pathologists. The overall survival and local control rates were 95.5% and 100%, respectively, at a median 37-month follow-up. The 3- and 5-year disease-free survival (DFS) rates were 64.4% and 56.3%, respectively. Of the 22 patients, 9 (8 Kadish C and 1 Kadish B) had disease recurrence. Of the nine patients, five had positive margins and two had closed margins; cervical lymph node recurrence occurred in six, and distant metastasis with or without cervical lymph node recurrence occurred in three. DFS analysis of risk factors showed no statistically significant differences, but positive margins were a significant recurrence factor in multivariate analysis. The local control rate of ONB treated with postoperative radiation therapy was 100%. This may be attributed to cross-departmental cooperation between head and neck surgeons, pathologists, and radiation oncologists, which resulted in accurate matching of CT images for treatment planning with the location of the tumor and positive margins. Longer follow-up periods are required to evaluate the effectiveness of our strategy.

Outcomes of extracranial stereotactic body radiation therapy for induced oligometastatic non-small cell lung cancer on novel systemic therapy.

Stereotactic body radiation therapy (SBRT) is often delivered in patients with oligometastatic disease (OMD). However, the specific subset of patients with polymetastatic non-small cell lung cancer (NSCLC) on novel systemic therapies who develop induced oligopersistant disease (OpersisD) or oligoprogressive disease (OprogD), as defined by the European Organisation for Research and Treatment of Cancer (EORTC) OMD classification, has not been well described. This study explores the outcomes of patients treated with this strategy. Patients with stage IV NSCLC being treated with osimertinib or immune checkpoint inhibitors (ICIs) who received extracranial SBRT for OpersisD or OprogD were identified in our retrospective analysis. Outcomes reported include progression-free survival (PFS), time to change of systemic treatment (TTCST), overall survival (OS), local control (LC) and treatment-related toxicity. Forty-nine patients received SBRT for OpersisD (34.7%) or OprogD (65.3%) at a median of 5.8 and 15.3 months after start of systemic therapy, respectively. 55.1% received concurrent osimertinib and 44.9% received ICI. Seventy-seven extracranial lesions were treated with various fractionation schemas. At a median of 18.8 months follow-up from first SBRT, LC was achieved in 92.2% of total lesions treated (71). The 1-year OS was 91.7% for OpersisD and 83.3% for OprogD. OpersisD compared to OprogD had a longer median PFS (18.3 vs. 6.1 months) and longer median TTCST (23.6 vs. 13.5 months), median OS was not reached for either cohort. On multivariate analysis, patients treated with osimertinib had shorter PFS (HR: 2.20; 95% CI: 1.01-4.82; P=0.048) and shorter TTCST (HR: 2.83; 95% CI: 1.09-7.33; P=0.032). One patient (2%) experienced grade 3 pneumonitis after SBRT, and no grade 4-5 toxicities were reported with SBRT treatment. This study indicates that SBRT for OpersisD or OprogD in Stage IV NSCLC patients on osimertinib or ICIs is safe, very well tolerated, and may prolong the time before needing a shift in systemic therapy. Further prospective research is needed to validate and expand upon these findings.

Stereotactic body radiation therapy for clinically diagnosed early‐stage non‐small cell lung cancer: Importance of accurate CT interpretation by experts

AbstractIntroductionThis study evaluated the clinical outcomes of stereotactic body radiotherapy (SBRT) for both pathologically diagnosed (PD) and clinically diagnosed (CD) early‐stage non‐small cell lung cancer (NSCLC) and explored the significance of accurate expert computed tomography (CT) interpretation.MethodsWe retrospectively analyzed 95 patients with early‐stage NSCLC who received SBRT at our institution. Patients were classified into CD and PD groups. Two chest radiologists retrospectively interpreted the pre‐SBRT CT images to determine the tumor subtype and probability of malignancy (PM). Clinical findings, CT features, and treatment outcomes were compared between the two groups. The survival rate of the CD group was analyzed separately according to the PM grade.ResultsMedian overall survival for the CD and PD groups was 6.0 and 5.4 years (P = 0.57), respectively. Median cause‐specific survival was 10.2 years in the CD group and not reached in the PD group (P = 0.76). In the CD group, lung cancer mortality was lower in the low PM group (25% [1 of 4]) than in the high PM group (47.4% [9 of 19]).ConclusionIt may be desirable to evaluate the PM of the nodule using expert CT interpretation to decide whether SBRT is indicated in CD early‐stage NSCLC.

254 survival outcome of chemotherapy and radiotherapy in patients with metastatic tonsillar cancer(M1)

254 survival outcome of chemotherapy and radiotherapy in patients with metastatic tonsillar cancer(M1)

Treatment Outcomes of Stereotactic Ablative Body Radiotherapy on Extra-cranial Oligometastatic and Oligoprogressive Breast Cancer: Mature Results from a Single Institution Experience

AimsEvidence shows stereotactic ablative body radiotherapy (SABR) is used as a non-invasive ablative therapy in the treatment of multisite oligometastatic (OM) and oligoprogressive (OP) diseases originating from metastatic breast cancer. This study aims to report the treatment outcomes and to investigate what factors that are prognostic in terms of local control, progression-free survival (PFS) and overall survival (OS) in patients receiving SABR for extracranial OM and OP diseases originating from metastatic breast cancer. Materials and methodsA retrospective review on treatment records of patients with OM and OP from metastatic breast cancer who underwent SABR at a single was carried out. SABR was performed with daily image-guided radiotherapy (IGRT) using a dedicated robotic SABR machine. Local control, PFS and OS were calculated using Kaplan-Meier statistics and the post-treatment toxicity data was scored following the CTCAE v4.0 protocol. Univariate and multivariate Cox regression tests were used in the subgroup analysis of prognostic factors on PFS and OS including patients’ age, types of follow-up imaging (staging CT only vs whole-body MR/PET), metastases status (OM vs OP), primary breast cancer tumour grade, hormone receptors (ER/PR/HER2) status, change of systemic treatments at SABR, number of metastases, SABR treatment sites and doses. Results56 metastatic breast cancer patients (38 patients with OM and 18 patients with OP) were involved in this retrospective review. The median follow-up was 35.6 months (range 4.0–132.9 months). The estimated local control at 1 , 2 and 5 years were 90.9%, 88.7% and 88.7%, respectively. The estimated median PFS was 19.2 months (95%CI 10.3–28.1 months); the PFS at 1, 2 and 5 years were 63.3%, 44.4% and 33.2%. The estimated OS at 1, 2 and 5 years were 98.0%, 91.9% and 74.3%, respectively with the estimated median OS of 105.1 months (95%CI 51.5–158.7 months). The vast majority of patients tolerated the treatment well with the commonest acute side effects as grade 1 fatigue. There were no statistically significant factors found in OS regression analysis. The types of follow-up imaging, metastases status, oestrogen receptor status, and number of metastases for SABR were statistically significant factors (p < 0.05) in the multivariate Cox regression analysis on PFS. ConclusionThere are limited studies published on the efficacy and post-treatment toxicities of metastatic breast cancer OM and OP SABR with adequate length of follow-up. This study confirmed that SABR was a safe, non-invasive treatment option for patients with extracranial OM and OP diseases originated from primary breast cancer in terms of the acceptable post-treatment toxicities.

186 (PB-093) Poster - A comparative study of outcome of axillary lymph node dissection vs axillary radiotherapy in early breast cancer patients with positive sentinel lymph node

186 (PB-093) Poster - A comparative study of outcome of axillary lymph node dissection vs axillary radiotherapy in early breast cancer patients with positive sentinel lymph node

O 09 - Radiotherapy utilization and outcomes from a contemporary study of brentuximab vedotin with chemotherapy in pediatric high-risk Hodgkin lymphoma

O 09 - Radiotherapy utilization and outcomes from a contemporary study of brentuximab vedotin with chemotherapy in pediatric high-risk Hodgkin lymphoma