ESTRO 38 Abstract book

S800 ESTRO 38

acceptable with no statistically differences between two groups. The treatment was well tolerated without statistically differences between two groups. Randomized trials with higher number of pts and longer follow-up are needed to confirm our results

Purpose or Objective The aim of this study was to validate previously developed radiomics models relying on just two radiomics features from 18 F-fluorodeoxyglucose positron emission tomography (PET) and magnetic resonance imaging (MRI) images for prediction of disease free survival (DFS) and locoregional control (LRC) in locally advanced cervical cancer (LACC). Material and Methods Patients with LACC receiving chemoradiotherapy were enrolled in two French and one Canadian centers. Pre- treatment imaging was performed for each patient. Multicentric harmonization of the two radiomics features was performed with the ComBat method. The models for DFS (using the feature from apparent diffusion coefficient (ADC) MRI) and LRC (adding one PET feature to the DFS model) were tuned using one of the French cohorts (n=112) and applied to the other French (n=50) and the Canadian (n=28) external validation cohorts. Results The DFS model reached an accuracy of 90% (95% CI [79%- 98%]) (sensitivity 92-93%, specificity 87-89%) in both the French (figure A) and the Canadian (figure B) cohorts. The LRC model reached an accuracy of 98% (95% CI [90%-99%]) (sensitivity 86%, specificity 100%) in the French cohort and 96% (95% CI [80%-99%]) (sensitivity 83%, specificity 100%) in the Canadian cohort. Accuracy was significantly lower without ComBat harmonization (82-85% and 71-86% for DFS and LRC, respectively). The best prediction using standard clinical variables was 56-60% only.

Electronic Poster: Clinical track: Gynaecological (endometrium, cervix,vagina,vulva)

EP-1475 Radiotherapy Is a Safe and Effective Salvage Treatment for Recurrent Cervical Cancer H.J. Kim 1 , W.S. Koom 2 , G.E. Kim 3 , Y.B. Kim 2 1 Gil Medical Hospital, Department of Radiation Oncology, Incheon, Korea Republic of ; 2 Yonsei Cancer Center, Department of Radiation Oncology, Seoul, Korea Republic of ; 3 Jeju National University Hospital, Department of Radiation Oncology, Jeju, Korea Republic of Purpose or Objective The feasibility of salvage radiotherapy (RT) for patients with recurrent cervical cancer after definitive treatment is contentious. The purpose of this study was to investigate the feasibility and benefit of RT, particularly intensity-modulated RT (IMRT), for salvage treatment in patients with recurrent cervical cancer. Material and Methods We retrospectively analyzed 125 patients with recurrent cervical cancer treated with RT at Yonsei Cancer Center between January 2007 and December 2016. All patients received salvage RT for the recurred or metastatic tumor mass. Irradiating dose and volume were determined depending on initial treatment. IMRT was selected in challenging cases, such as re-irradiation or for patients for whom implementing a satisfactory 3-dimensional conformal RT plan was challenging. Results The median follow-up period was 5.5 years (range, 10.8 months to 41 years). The 5-year local failure-free survival (LFFS) and progression-free survival (PFS) rates were 63.9% and 39.6%, respectively. The 5-year overall survival (OS) rate was 66%; 10-year OS reached 51%. The median PFS rates in patients with locoregional failure, distant metastases, or both were 45.4, 29.1, and 14.7 months, respectively (p = 0.005). For the 45 patients that received re-irradiation, 5-year LFFS, PFS, and OS rates were 47.1%, 33.2%, and 66.5%, respectively. Late complications ≥ grade 2 were observed in 12 patients (12/125, 9.6%). Conclusion Our data suggest that salvage RT is safe and effective against recurrent cervical cancer. IMRT is a safe and effective salvage modality for these patients, including those requiring re-irradiation. EP-1476 Validation of a combined PET and MRI radiomics model for prediction of recurrence in cervical cancer F. Lucia 1 , D. Visvikis 2 , M. Vallières 2 , M. Desseroit 2 , O. Miranda 1 , P. Robin 3 , P.A. Bonaffini 4 , J. Alfieri 5 , I. Masson 6 , A. Mervoyer 6 , C. Reinhold 4 , O. Pradier 1 , M. Hatt 2 , U. Schick 1 1 CHRU Brest, Radiation oncology, Brest, France ; 2 LaTIM- INSERM- UMR 1101, University of Brest- ISBAM- UBO- UBL- Brest- France, Brest, France ; 3 CHRU Brest, Nuclear Medicine, Brest, France ; 4 McGill University Health Centre MUHC, Department of Radiology, Montreal, Canada ; 5 McGill University Health Centre MUHC, Department of Radiation Oncology, Montreal, Canada ; 6 Institut de Cancerologie de l’Ouest, Radiation Oncology, Nantes, France

Figure A

Figure B

Conclusion The previously developed PET/MRI radiomics predictive models were successfully validated in two independent external cohorts. A proposed flowchart for improved management of patients based on these models should now be confirmed in future larger prospective studies.