ESTRO 2021 Abstract Book

S1065

ESTRO 2021

PO-1293 Dosimetric predictors of brachytherapy in cervical cancer: an experience from a developing country E. Manea 1,1 , A. Munteanu 1 , A. Constantin 2 , A.D. Zara 3 , I. Butuc 4 , M. Oprisan 4 , L. Miron 5 1 “Gr. T. Popa” University of Medicine and Pharmacy Iasi, Radiotherapy, Iasi, Romania; 2 Regional Institute of Oncology Iasi, Romania, Physics , Iasi, Romania; 3 Regional Institute of Oncology Iasi, Physics , Iasi, Romania; 4 Regional Institute of Oncology Iasi, Physics, Iasi, Romania; 5 “Gr. T. Popa” University of Medicine and Pharmacy Iasi, Oncology, Iasi, Romania Purpose or Objective To report the incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicities in our first experience of locally advanced cervical cancer (LACC) patients (pts) treated with image guided adapted brachytherapy (IGABT) on magnetic resonance imaging (MRI). Materials and Methods 52 consecutive pts with LACC treated with chemo-radiotherapy and high dose rate (HDR) IGABT from April 2018 – October 2020 were included. Pts received external beam radiotherapy (EBRT) including nodal boost sequentially/Simultaneous Integrated Boost (SIB) +/- concomitant chemotherapy and HDR IGABT. The high-risk CTV (CTV HR ), intermediate-risk CTV (CTV IR ), organ at risks (bladder, rectum, sigmoid, and bowel) contouring and treatment planning respected European Brachytherapy European Society for Radiation Oncology (GEC- ESTRO) recommendations. Cumulative doses were calculated using the linear-quadratic model (EQD 2 ). The goal of overall treatment time (OTT) was under 50 days. The follow-up was performed every three months for the first two years and six months thereafter. The toxicity was examined as occurrence of late morbidity assessed using Common Terminology Criteria for Adverse event 4.03 considering following events for GU: frequency, incontinence, cystitis, bleeding, stenosis and fistula and for GI: diarrhea, flatulence, abdominal pain, obstruction, stenosis, bowel fistula. Statistical analyses were used to investigate clinical and dosimetric predictors of toxicity. Results The median age of the pts was 56 years. Stage IIB, IIIC1r and IIIC2r were 12 pts, 25 pts and 15 pts, respectively. The mean D 90 for the CTV HR and CTV IR were 86 Gy and 67 Gy. Median doses to the D 2cc of bladder, rectum, sigmoid, and small bowel were 82.5 Gy, 67 Gy, 66.5 Gy, and 60.3 Gy, respectively. Median doses to D 0.1cc for bladder, rectum, sigmoid, and small bowel were 96.5 Gy, 78 Gy, 74.3 Gy and 65.6 Gy, respectively. 41 pts respected OTT. Median follow-up was ~20 months. After the treatment, 92.3 % achieved locoregional remission. GU and GI morbidity was 15.28% and 13.46%. 23.07% presented grade 2-3 late morbidity. The overall rate of GU adverse event grade 1 was 5.76% (n=3) and >grade 2 was 9.61% (n=5). D 2cc bladder ≥80 Gy (EQD 2-3 ) was 4 of the 5 pts. For pts with severe adverse events the median dose D 0.1cc bladder was 110 Gy. No grade 1 GI toxicity was reported. The overall rate of GI adverse event >grade 2 was 13.46% (n=7). D 2cc rectum ≥65 Gy had 5 of the 7 pts and 4 had D 2cc sigmoid ≥65 Gy. Median dose D 0.1cc for rectum and sigmoid was 82.65 Gy and 76.2 Gy. There were no statistically significant prognostic factors for adverse events with diabetes, hypertension, smoking and OTT. Conclusion The most important toxicities have been noted for D 2cc ≥65 Gy for the rectum/sigmoid and D 2cc ≥80 Gy for bladder, suggesting that we should limit the dose. IGABT decreases morbidities and should be considered for wider implementation in developing countries to improve outcomes. PO-1294 Timing to assess the clinical response after chemoradiotherapy in locally advanced cervical cancer R. Autorino 1 , V. Lancellotta 2 , M. Campitelli 2 , A. Nardangeli 3 , M.G. Ferrandina 4 , N. Bizzarri 4 , B. Gui 5 , L. Russo 5 , M. Ferioli 6 , L. Tagliaferri 2 , G. Macchia 7 , M.A. Gambacorta 3 1 UOC Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Rome, Italy; 2 UOC Radioterapia Oncologica, 1Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Rome, Italy; 3 UOC Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Rome, Italy; 4 Ginecologia oncologica, Department of Woman and Child Health and Public Health, Woman Health Area, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy; 5 Radiologia, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, Rome, Italy; 6 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 7 Radiation Oncology Unit, Gemelli Molise Hospital, Università Cattolica del Sacro Cuore, Campobasso, Italy Purpose or Objective There is no agreement on the standard assessment of response in patients with locally advanced cervical cancer (LACC) after definitive treatment with concurrent chemo-radiotherapy followed by interventional radiotherapy (IRT, brachytherapy). Aim of the present abstract was to investigate the best timing for assessing the clinical response after chemoradiotherapy in LACC patients. Materials and Methods We retrospectively analyzed the pelvic magnetic resonance imaging (MRI) and 18-Fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) data of 38 LACC patients between January 2019 and July 2020. Inclusion criteria were (a) histologically proven squamous cell cervical cancer or adenocarcinoma; (b) stage IB2-IVA FIGO 2018 (c) availability of a baseline pelvic MRI and a total body 18F-FDG PET/CT (d) availability of a pelvic MRI and whole-body 18F-FDG PET/CT performed three and six months after the end of IRT. All patients received intravenous cisplatin (40 mg/m²/weekly), external beam radiotherapy (45 Gy in 25 daily fractions ± simultaneous lymph-nodes boost) and interventional radiotherapy (28 Gy/twice/weekly).