ESTRO 2022 - Abstract Book

S1140

Abstract book

ESTRO 2022

Conclusion MRI and 18FDG-PET/CT are useful tools in the evaluation of early response after treatment in locally advanced cervical cancer. Early response assessed either by MRI or 18FDG-PET/CT is a good prognostic factor to estimate specific-cause survival in these patients. Further investigation should be done to stablish the reliability of both techniques to stablish them as definitive prognostic tools to estimate survival rates.

PO-1345 Early Response In 18fdg-Pet/Ct As Prognostic Factor In Locally Advanced Cervical Cancer

M.I. Garrido Botella 1 , M. Rodriguez Roldan 1 , M. Teja Ubach 1 , M. Gonzalez Cantero 1 , I. Rodriguez Rodriguez 1 , E. Gonzalez Del Portillo 1 , B. Belinchón Olmeda 1 , R. Morera 1

1 HOSPITAL UNIVERSITARIO LA PAZ, RADIATION ONCOLOGY, MADRID, Spain

Purpose or Objective Standard treatment in locally advanced cervical cancer (LACC; FIGO stage ≥ IB2) is definitive concurrent chemoradiotherapy (cCRT), with external beam radiotherapy and weekly cisplatin, followed by brachytherapy (BT). 18F-fluorodeoxyglucose positron emission tomography – computed tomography (18FDG-PET/CT) is a useful tool to assess response after treatment. Some studies have analyzed specific overall survival (OS) according to physiologic response using 18FDG-PET/CT. In the early assessment of tumoral response, the regression of the tumor after treatment could be a survival predictor. By this study we want to describe survival rates in the first 24 month of follow up according to early response using 18FDG- PET/CT. Materials and Methods A retrospective observational study was performed, including patients (n=77) with LACC treated with cCRT (treatment volume defined according to RTOG guidelines, with 3D conformed radiotherapy or volumetric modulated arc therapy with 6-MV photons, to a total dose of 45-50.4Gy, 1.8Gy per fraction 5 days a week, with dose escalation if positive pelvic nodes or extracapsular extension on paraaortic lymphadenectomy were objectified, and 2-7 cycles of weekly cisplatin) followed by high dose rate BT (total dose of 26Gy, 6.5Gy per fraction, twice a week, with Iridium-192, using Ring or Fletcher applicator) between 2010-2018 in our institution. Response to treatment was objectified 18FDG-PET/CT in all patients performed 3 months after treatment. Results were classified as complete response (CR), partial response (PR), stable disease (SD), or disease progression (DP). We described survival rates in patients with complete or partial response or stable disease compared to survival rates in patients with disease progression. Results OS after 24 months of follow up in patients with PR and CR to treatment or SD objectified in early 18FDG-PET/CT was 92.6% and in patients with DP was 11.1% (p<0.001). Better survival rates were objectified according to better response with 93.9% of patients with CR, 88.9% of patients with PR, and 11.1% of patients with DP alive after 24 months of follow up. Response to treatment or SD after treatment affects OS, reducing decease risk 98.6% (p<0.001 by Cox Regression).