ESTRO 2022 - Abstract Book

S74

Abstract book

ESTRO 2022

in extracellular matrix (ECM) deposition and reorganisation, signaling, and inflammation [1]. The purpose of the present study was to validate the expression kinetics over a post-irradiation period of 1-6 days using a different platform. Materials and Methods Early passage skin fibroblast strains (GS3, GS4, GS5) from completely anonymised individual donors were grown in AmnioMax medium as described [1]. RNA was isolated at daily intervals on day 1-6 after irradiation with a single dose of 4 Gy (6 MV X-rays) and analysed on Breakthrough 20k human expression microarrays with ‘dye-swap’ replicates. SAM analysis was done with ‘R’ and JMP Genomics software, and pathway enrichment analysis with the ReactomePA library and ‘Reactome’ pathways. Validation of selected genes and time points in independent experiments was performed with quantitative real- time PCR (qPCR) and Western blotting. Results The majority of significant genes showed steady up- or downregulation with increasing time after irradiation. Cell-cycle related genes showed marked downregulation on day 1 and further declined more slowly at later time points. Very few genes showed early upregulation on day 1 with little further increases whereas several genes showed a strong late upregulation with steeper increases from day 2 to 4. Pathway analysis confirmed downregulation of pathways related to cell cycle progression and mitosis as well as upregulation of pathways related to extracellular matrix deposition and remodeling. Signalling pathways (including Interleukin-4 and Interleukin-13 signallng) were overrepresented on day 2 but not on day 5 supporting the notion of a pro-fibrotic response leading to increased ECM deposition. Although most genes showed similar changes in the three individual fibroblast strains, COL11A1 showed larger differences between the three fibroblast strains consistent with the previous study [1], indicating that variations in response of individual donors’ fibroblasts can be detected in vitro . Conclusion The results broadly validated and extended the findings from the previous study [1] and supports the use of early-passage fibroblasts as a model for studying fibrogenesis in vitro . Ref. [1]: Herskind et al. , Front Cell Dev Biol 9 :539893 (2021). A. Budrukkar 1 , V. Murthy 2 , S. Kashid 3 , M. Swain 3 , V. Rangarajan 4 , S. Ghosh Laskar 3 , S. Kannan 5 , S. Kale 6 , R. Upereti 6 , S. Gawli 3 , P. Pai 7 , G. Pantvaidya 7 , T. Gupta 2 , J.P. Agarwal 3 1 Tata Memorial Hospital, Homi Bhabha National Institute, , Department of Radiation Oncology, Mumbai, India; 2 Tata Memorial Hospital and Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Homi Bhabha National Institute (HBNI), Department of Radiation Oncology, Mumbai, India; 3 Tata Memorial Hospital, Homi Bhabha National Institute, Department of Radiation Oncology, Mumbai, India; 4 Tata Memorial Hospital, Homi Bhabha National Institute, Department of Nuclear Medicine, Mumbai, India; 5 Tata Memorial Hospital and Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Homi Bhabha National Institute (HBNI), Clinical Research Secretariat, Mumbai, India; 6 Tata Memorial Hospital, Homi Bhabha National Institute, Department of Medical Physics, Mumbai, India; 7 Tata Memorial Hospital, Homi Bhabha National Institute, Department of Head Neck Surgery, Mumbai, India Purpose or Objective To compare clinical outcomes of intensity modulated radiation therapy (IMRT) alone vs IMRT+ brachytherapy in patients with early staged oropharyngeal squamous cell cancers (OSCC). Materials and Methods Newly diagnosed patients with biopsy proven stage I and II OSCC of were randomized to IMRT alone vs IMRT + brachytherapy. Randomization was done using computer generated block randomization (1:1) at a single centre. All patients received IMRT to a dose of 50Gy/25#/5 weeks in phase I. In phase II patients in the IMRT arm received 20Gy/10#/2 weeks and in the brachytherapy arm received high dose rate brachytherapy to a dose 21Gy/7fractions/2 fractions per day. Primary endpoint of the trial was reduction in xerostomia at 6 months. Evaluation of xerostomia was done using T99 salivary scintigraphy, RTOG toxicity criteria, EORTC quality of life questionnaire and xerostomia questionnaire (XQ) at 3, 6, 12 and 24 months. Reduction in salivary function using scintigraphy was quantified by salivary excretion fraction (SEF) ratio. Post treatment SEF ratio <45% was considered as severe salivary toxicity. Secondary endpoints were local control (LC), disease free survival (DFS) and overall survival (OAS). Results Between November 2009 to January 2020, 90 patients were randomized to IMRT (N=46) or IMRT plus brachytherapy (N=44). Seven patients in the brachytherapy arm could not receive brachytherapy (technical feasibility-5, unfit for anesthesia -2) and were treated with IMRT. The analysis was done both by intention to treat and per protocol. At 6 months, SEF <45% for ipsilateral parotid was observed in 15.2% patients in brachytherapy arm while it was seen in 43.8% patients in IMRT arm (p<0.01) with similar trend at 12 and 24 months (p<0.01) (Fig 1). For contralateral parotid at 6 months SEF <45% was observed in 12% in brachytherapy arm while it was 25% in IMRT arm (p=0.18) with similar trend at 12, 24 months (p=0.13). At 6 months RTOG Grade ≥ 2 xerostomia was 4% in brachytherapy arm while it was 12.5% in IMRT arm (p=0.33). RTOG Grade ≥ 2 xerostomia over the time period was 11. 4% in brachytherapy arm while it was 28.3% in IMRT arm (p=0.04). The mean xerostomia score of XQ at 6 months was 28 for brachytherapy and 37 for IMRT with similar trend at 12 and 24 months (p=0.02). At a median follow up of 42.5 months the 2 year LC was 69% in brachytherapy arm and 61.4% in IMRT arm (p=0.23). There was a trend towards improved LC with brachytherapy in per protocol analysis (74.4% vs 58.7% p=0.07). The 2 year OAS was 70.3% in brachytherapy arm and 72.6% in IMRT arm (p=0.39) Proffered Papers: Late-breaking OC-0100 IMRT vs IMRT and brachytherapy for early oropharyngeal cancers (Brachytrial) : A randomized trial