ESTRO 2023 - Abstract Book

S1175

Digital Posters

ESTRO 2023

The pilot phase of this study consisted of two high-throughput experiments. In the first run, we screened formalin-fixed paraffin-embedded (FFPE) breast cancer specimens for microRNAs using microarrays (Agilent®). Secondly, we used Affymetrix GeneChips® to screen for target proteins in the same tissue samples. Subsequently, an in-silico analysis was conducted to detect differentially expressed microRNAs and target genes using Linear Models for Microarray Data (LIMMA). Additionally, we compared potential targets with publicly available databases (TargetScan, miRDB, PITA, DIANA, DIANA Cancer, miRCarta). In the validation phase of this study, these results were validated with RT-qPCR (microRNA) as well as droplet digital PCR (target proteins) in an independent patient cohort. Results Hsa-miR-3651 was found to be differentially expressed between patients who experienced local relapse compared to those without (N = 23; p = 0.0035). This result could be validated in an independent cohort of 87 patients using RT-qPCR (p < 0.0005). In a second step FERM domain protein 3 (FRMD3) was found to be the most down-regulated protein (N = 21; p = 0.0016). Computational analysis employing different prediction algorithms revealed FRMD3 as a likely downstream target of hsa-miR-3651 with a 8mer binding site between the two molecules, which could be corroborated by droplet digital PCR in an independent patient set (N = 20, p = 0.134). Conclusion The current study revealed that hsa-miR-3651 might be a predictor of LC in early breast cancer via its putative target protein FRMD3. Since microRNAs interfere in multiple pathways, the results of this hypothesis generating study may contribute to the development of tailored therapies for breast cancer in the future. 1 Warren Alpert Medical School of Brown University, Department of Radiation Oncology, Providence, USA; 2 Rush University Medical Center, Department of Radiation Oncology, Chicago, USA; 3 Rush University Medical Center, Department of Hematology, Oncology, and Cell Therapy, Chicago, USA Purpose or Objective Neutrophil-to-lymphocyte ratio (NLR) is a surrogate for systemic inflammation and the tumor microenvironment. Recently, pre-treatment NLR has been shown to be a prognostic factor in various malignancies. Stereotactic body radiotherapy (SBRT) has been linked to systemic antitumor T-cell response via immune stimulation. Therefore, we investigated the prognostic value of percent (%) change in NLR before and after SBRT in early-stage lung cancer. Materials and Methods Patients treated with SBRT for stage I-II lung cancer from 2012-2020 were retrospectively identified. Pre-, post- treatment and % change in NLR were calculated from full blood counts obtained in closest proximity to SBRT. Patients were divided into two cohorts based on % change in NLR; receiver operator curve analysis was used to find the optimal cut point for % change in NLR. Overall survival (OS) was estimated by the Kaplan-Meier (KM) method. Intra- and extra-thoracic outcomes were calculated using the cumulative incidence model with competing risk for death. Univariate and multivariate Cox proportional hazards analyses were performed to identify the association of % change in NLR with OS, intra-&extra-thoracic outcomes. The models were adjusted for confounding variables. Results 102 patients had full blood counts pre and post SBRT. The optimal cut point for NLR change with respect to OS was a 54.2% increase. Key baseline characteristics (ie stage, age, smoking, SBRT dose, fractions, BED) were well balanced across the cohorts, except for sex. Patients with % change in NLR >54.2% had significantly worse OS (2-yr: 79.2% vs 41.7%) and distant recurrence (2-yr: 18.3% vs 38.5%). % change in NLR was a significant predictor for worse OS (HR 2.58, 95%CI 1.24-5.37, p<0.05) and distant recurrence (HR 3.01, 95%CI 1.18-8.08, p<0.05) on multivariate analysis. There were no significant associations of change in NLR with lobar, local, or nodal recurrence. Conclusion Percent increase in NLR following SBRT is associated with higher distance recurrence and worse survival in patients with early-stage lung cancer. If prospectively validated, NLR could be a cost-effective marker to identify high-risk patients who may benefit from closer surveillance and possibly even treatment escalation. PO-1451 Neutrophil-lymphocyte ratio dynamics associated with survival after SBRT for stage I-II lung cancer S. Shahamatdar 1 , K. King 2 , S. Roy 2 , M. Batus 2 , M.J. Fidler 3 , P. Bonomi 3 , G. Marwaha 2 , M. Chowdhary 1

Poster (Digital): Urology

PO-1452 Toxicity and early findings in a post-prostatectomy ablative radiation therapy multicentric trial

R. Lucchini 1 , C. Franzese 2 , S. Vukcaj 3 , G. Purrello 1 , D. Panizza 4 , V. Faccenda 4 , S. Andreoli 5 , G.L. Poli 5 , D. Baldaccini 2 , L. Lo Faro 2 , S. Tomatis 2 , L.F. Cazzaniga 3 , M. Scorsetti 2 , S. Arcangeli 1 1 University of Milan Bicocca, Radiation Oncology Department, Milan, Italy; 2 Humanitas Clinical and Research Center - IRCCS, Department of Radiotherapy and Radiosurgery, Rozzano, Italy; 3 ASST Papa Giovanni XXIII, Department of Radiation Oncology, Bergamo, Italy; 4 ASST Monza, Medical Physics Department, Monza, Italy; 5 ASST Papa Giovanni XXIII, Department of Medical Physics, Bergamo, Italy

Purpose or Objective