ESTRO 2025 - Abstract Book

S1671

Clinical - Sarcoma & skin cancer & malignant melanoma

ESTRO 2025

1366

Poster Discussion Assessing the Predictive Role of Volumetric Changes in Soft Tissue Sarcomas of the Extremities Following Neoadjuvant Radiotherapy Silvia Cammelli 1,2 , Viola Laghi 1 , Paolo Spinnato 3 , Erika Galietta 1 , Costanza M Donati 1 , Letizia Cavallini 1 , Giuseppe Bianchi 4 , Alberto Righi 5 , Massimiliano De Paolis 6 , Andrea Sambri 6 , Annalisa Cortesi 7 , Claudio Malizia 8 , Davide M Donati 4 , Alessio G Morganti 1 1 Radiation Oncology, IRCCS Azienda Ospedaliero-Universitaria of Bologna, Bologna, Italy. 2 Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy. 3 Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 4 Orthopedic musculo-skeletal oncology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 5 Department of Pathology, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 6 Orthopedic and Traumatology Unit, IRCCS Azienda Ospedaliero-Universitaria of Bologna, Bologna, Italy. 7 Radiotherapy Unit, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", Forlì-Cesena, Italy. 8 Nuclear Medicine, IRCCS Azienda Ospedaliero-Universitaria of Bologna, Bologna, Italy Purpose/Objective: To evaluate the radiological response of localized, high-grade, primary soft tissue sarcomas (STS) of the extremities treated with neoadjuvant radio(chemo)therapy, using RECIST, Choi criteria, and volumetric changes. Material/Methods: Fifty-nine patients (median age 52 years, range: 16-84) with STS of the extremities underwent pre-operative external beam radiotherapy (RT), receiving a median dose of 50 Gy. MRI scans of the affected region and chest TC +/- PET were performed before RT, after RT (before surgery), and during follow-up (FU). All MRIs were reviewed by a single radiologist specializing in musculoskeletal oncology, using semi-automatic software (Carestream Vue PACS c 12.2.6.2000019) for volume measurements. Results: MRI scans were conducted at a median of 5.71 weeks before and 4.43 weeks after RT. The median percentage change in maximal tumor diameter was -12.50% (range -74.63% to +92.78%). According to RECIST and Choi criteria, partial response was seen in 20.34% and 55.93% of cases, stable disease in 71.90% and 27.12%, and progressive disease in 8.47% and 16.95%, respectively. Tumor volume decreased in 43 out of 59 patients, with a median change of -37.00% (range from +415% to -99.00%). The log-rank test revealed that radiological responses evaluated by RECIST, Choi criteria, and volume changes did not significantly impact 5-year local control, distant metastasis-free survival, disease-free survival, or overall survival (Table 1).

Table 1 : actuarial results and univariate analysis.

Conclusion: Our analysis indicates that neither RECIST and Choi criteria nor volumetric changes effectively predict oncological outcomes. This suggests the necessity for exploring additional parameters or predictive models that could more accurately forecast treatment response and patient prognosis in soft tissue sarcomas of the extremities following neoadjuvant radio(chemo)therapy.