ESTRO 2025 - Abstract Book

S860

Clinical - Gynaecology

ESTRO 2025

3-Park, H. J., et al. (2015). Stereotactic body radiotherapy for recurrent or oligometastatic uterine cervix cancer. Anticancer Res. , 4-Shen, J., et al. (2022). Clinical application of radiotherapy in patients with oligometastatic ovarian cancer. Discover. Oncology , doi:10.1007/s12672-022-00540-y

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Digital Poster Higher disease-free survival observed for complete response after SBRT in oligometastatic gynecologic tumors Gaia Parma 1 , Sara Saufi 1 , Andrei Fodor 1 , Chiara L Deantoni 1 , Fiorino Claudio 2 , Antonella Del Vecchio 2 , Stefano Arcangeli 3,4 , Nadia G Di Muzio 1,5 1 Radiotherapy, IRCCS San Raffaele, Milan, Italy. 2 Medical Physics, IRCCS San Raffaele, Milan, Italy. 3 Radiotherapy, IRCCS San Gerardo dei Tintori, Monza, Italy. 4 Radiotherapy, Università degli Studi Milano Bicocca, Monza, Italy. 5 Radiotherapy, Vita-Salute San Raffaele University, Milan, Italy Purpose/Objective: MITO multicenter retrospective trials demonstrated the significant role that radiotherapy (RT) can play in oligometastatic gynecological cancers (1,2,3). In this retrospective study we analyzed outcomes and safety of robotic stereotactic body radiotherapy (SBRT) performed in our institution for the oligometastatic disease from gynecological tumors. Material/Methods: From January 2018 to August 2024 a total of 99 oligometastases were treated in 54 patients with gynecological cancer with robotic SBRT (CyberKnife®, Accuray, Sunnyvale CA, USA). Median prescribed dose was 40 (18-60) Gy in a median of 5 (1-8) fractions, at a median isodose of 79.0% (67-83%). Oligometastatic lesions were localized in: lymph nodes in 38.4% of cases, lung in 37.4%, liver in 8.1%, bone in 7.1%, brain in 6%, and other sites in 3% of cases. Endometrial cancer was the most common primary tumor (63% of patients). Median GTV was 2.58cc. Median age at treatment was 67 years (22-91). Toxicity was assessed using CTCAE v 5.0 criteria. The primary endpoint was the complete response rate to SBRT. The secondary aims were local relapse-free survival (LRFS), disease-free survival (DFS), overall survival (OS), as well as toxicity. Results: Median follow-up was 36 months. Grade (G)1 and 2 acute toxicity was observed in 8.1% of patients. No G≥3 acute toxicity was observed. Late toxicity was low, only 5% of patients presented a G1 toxicity. Complete response was found in 61.6% of lesions (only 5% of patients did not respond to SBRT). Twelve- month LRFS and DFS were 89.4% and 37%; at 24 and 36 months LRFS and DFS were 87.9% and 19.9%, respectively (Fig. 1). OS was 81.5% at 12 months, 68% at 24 months and 19.9% at 36 months. The 1- and 2 year actuarial DFS rate were 42% and 23% in patients with complete response versus 23% and 9% in patients with partial response, stable, or progressive disease (p=0.005) (Fig.2).