ESTRO 2021 Abstract Book

S528

ESTRO 2021

Conclusion The present analysis showed for the first time the benefit of adding PRSi in toxicity risk prediction models. As the PRSi included only 13 validated SNPs, the performance of PRSi and future toxicity risk prediction models should be improved by adding additional SNPs from new discovery studies. Some common (with a frequency ≥10%) SNP-SNP interactions were found, including up to 13 alleles from 13 SNPs. Funding: REQUITE, European Union's Seventh Framework Programme for research, technological development and demonstration, grant agreement no. 601826. RADprecise, ERA PerMed Network, 1st Joint Transnational Call for Proposals (2018), Reference Number: ERAPERMED2018-244. PH-0657 Single-Fraction versus Double-Fraction HDR boost for high-risk prostate cancer: long-term outcomes A. Goñi Ramirez 1 , B. De Paula Carranza 1 , P. Fernández Gonzalo 2 , E.M. Sáenz de Urturi 1 , N. Bultó Boqué 1 , M. Egiguren Bastida 2 , M. Pagola 1 , D.I. Ortiz de Urbina 1 , D. Roura 1 , J. Belloso 3 , G. Garmendia 3 , A. Ayete Andreu 4 , V. Pastor Sanchis 5 , A. Bartrés Salido 6 , N. Suarez 5 , M. Erzilbengoa 6 , J. Rosa Nieto 1 1 Fundación Onkologikoa - UGC Oncología Gipuzkoa, Radiation Oncology, San Sebastian, Spain; 2 Fundación