ESTRO 2022 - Abstract Book

S1111

Abstract book

ESTRO 2022

1 Koç University, School of Medicine , Department of Radiation Oncology , Istanbul, Turkey; 2 Koç University, School of Medicine, Department of Medical Oncology, Istanbul, Turkey; 3 Koç University, School of Medicine, Department of General Surgery, Istanbul, Turkey; 4 Koç University, School of Medicine, Department of Radiation Oncology, Istanbul, Turkey Purpose or Objective The non-operative management (NOM) approach in the treatment of locally advanced rectal cancer provides avoidance of possible early and long-term morbidity, mortality, and organ loss of surgery in patients with complete clinical response (cCR) after total neoadjuvant therapy (TNT). Our aim is to evaluate the survival and local or systemic recurrence in patients with locally advanced rectal cancer considered cCR after TNT and followed up with NOM. Materials and Methods Patients diagnosed with locally advanced rectal cancer who applied to Vehbi Koç Foundation Health Institutions were evaluated with magnetic resonance imaging, FDG-Positron emission tomography with computed tomography, and endoscopy after TNT. The patients that had cCR according to imaging and endoscopic response were followed up with NOM, and survival, local or systemic recurrence was assessed in this subgroup of patients. Results Between 2014 and 2021, 201 out of 270 locally advanced rectal cancer (T3N+) patients in VKV Health institutions who met the criteria were recruited to the TNT approach. Among these patients, 53 (26%) with cCR were included in the NOM protocol. During the median 33-month median follow-up, regrowth was observed in 2 (3%) of the patients who underwent NOM, and these patients had salvage surgery. Surgery could not be performed in one patient because of distant metastasis, and he received systemic therapy again. There was no survival difference in patients with partial complete response and cCR who did not accept NOM and underwent total mesorectal excision compared to the patients who were followed up with the NOM approach. Conclusion NOM, especially in selected patients after total neoadjuvant therapy, is a promising approach where sphincter and rectal functions may be preserved, allowing salvage surgery in local recurrences that can be applied with close follow-up and patient compliance and will change our practice. NOM is a promising approach where sphincter and rectal functions may be preserved, allowing salvage surgery in local recurrences, especially in selected cases after total neoadjuvant therapy. It can be applied by providing close follow-up as well as patient compliance and will change our practice. V. De Luca 1 , L. Boldrini 1 , S. Manfrida 1 , S. Reina 2 , D. Carano 3 , R. Gatta 4 , C. Votta 1 , L. Tagliaferri 1 , F. Marazzi 1 , S. Mariani 2 , B. Barbaro 5 , V. Valentini 6 , M.A. Gambacorta 6 1 Fondazione Policlinico Universitario A. Gemelli IRCCS, Radiation Oncology, Rome, Italy; 2 Università Cattolica del Sacro Cuore, Radiation Oncology, Rome, Italy; 3 Università Cattolica del Sacro Cuore, Radiology, Rome, Italy; 4 Università degli Studi di Brescia, Clinical and Experimental Sciences, Brescia, Italy; 5 Fondazione Policlinico Universitario A. Gemelli IRCCS, Radiology, Rome, Italy; 6 Fondazione Policlinico Universitario A. Gemelli IRCCS, Radiation Oncology, Rome, Italy Purpose or Objective Although definitive chemo-radiotherapy (CRT) approach results in a high rate of disease control in anal cancer, efforts are being made to move from one treatment “fits-for-all” toward a direction of an increasingly personalized treatment, that should be tailored to specific patient and tumor characteristics through the use of quantitative imaging biomarkers. The aim of this study is to evaluate whenever radiomics predict 2-years disease specific survival (DSS) in locally advanced squamous anal cancer patients, who underwent exclusive concurrent radical CRT. Materials and Methods We analyzed the consecutive patients treated at our Institution between August 2011 and September 2019, whose characteristics are illustrated in Table 1. Treatment consisted of concomitant CRT with IMRT/VMAT technique and a Simultaneous Integrated Boost (SIB), eventually followed by an EBRT/brachytherapy boost. Median dose to primary tumor was 55 Gy (range 41.80 – 55.80 Gy). Median overall treatment time was 91.5 days. 2 years-DSS was considered as primary outcome of the prediction. The Gross Tumor volume (GTV) was manually segmented on the staging 1.5 T T2 MRI images for all the patients (figure 1a). A LoG filter was applied ( σ 0.5-3.5 with 0.05 step) and radiomics features were extracted for all possible σ values using MODDICOM. PO-1317 Chemoradiotherapy-treated anal cancer patients radiomics-based stratification to predict DSS.