@article {PintoA274, author = {Patr{\'\i}cia Pinto and Valentina Chiappa and Juan Luiz Alcazar and Dorella Franchi and Antonia Carla Testa and Lil Valentin and David Cibula and Daniela Fischerov{\'a}}, title = {2022-RA-891-ESGO Preoperative assessment of non-resectability in patients with ovarian cancer using imaging (ISAAC study) {\textendash} an interim analysis}, volume = {32}, number = {Suppl 2}, pages = {A274--A274}, year = {2022}, doi = {10.1136/ijgc-2022-ESGO.584}, publisher = {BMJ Specialist Journals}, abstract = {Introduction/Background The aim of the European multicentric prospective study (ISAAC study, Imaging Study on Advanced ovArian cancer) was to test the non-inferiority of abdomino-pelvic ultrasound compared to computed tomography (CT) and whole-body diffusion-weighted magnetic resonance imaging (WB-DWI/MRI) in prediction of surgical outcome in patients with ovarian/tubal/peritoneal cancer.Methodology All consecutive patients, with suspected ovarian cancer planned for surgery underwent preoperative prediction of non-resectability with ultrasound, CT and WB-DWI/MRI at 5 european centres. The prediction of non-resectability was based on the European Society of Gynecologic Oncology (ESGO) criteria of non-resectability. Findings were compared to the reference standard (surgical outcome).Results The interim analysis looked at data of the first 59 patients enrolled between 01/2020 and 07/2021. They underwent ultrasound and CT (n=59), and WB-DWI/MRI (n=50). Among them, 83\% (49/59) had advanced-stage and 17\% (10/59) had early-stage ovarian cancer. Diagnostic laparoscopy only was performed in 12\% (7/59) of the cases. In the remaining 88\% (52/59) laparotomy was performed with no residual disease at the end of surgery (R0) in 75\% (39/52), residual disease <=1 cm in 10\% (5/52) and residual disease \>1 cm in 15\% (8/52). The ultrasound imaging was non-inferior neither to CT (p-value =0.029) nor to WB-DWI/MRI (p-value = 0.036). Regarding the prediction of resectability, ultrasound obtained the best results with an AUC of 0.85, sensitivity of 91.3\% and specificity of 85.7\%. CT and WB-DWI/MRI had similar results regarding AUC and sensitivity (0.79 vs 0.78 and 88.6\% vs 87.5\%), with lower specificity for CT (68.8\% vs 86\%).Conclusion This interim analysis represents the first prospective study documenting that ultrasound is not inferior to CT and WB-DWI/MRI in predicting the non-resectability of patients with ovarian cancer. ESGO criteria are easy to apply in preoperative imaging without a need for more complex scoring system.}, issn = {1048-891X}, URL = {https://ijgc.bmj.com/content/32/Suppl_2/A274.1}, eprint = {https://ijgc.bmj.com/content/32/Suppl_2/A274.1.full.pdf}, journal = {International Journal of Gynecologic Cancer} }