ESTRO 2025 - Abstract Book

S203

Brachytherapy - General

ESTRO 2025

Conclusion: This innovative CBCT scanner may be a significant issue for adaptive gynecological BT planning. The ability to conduct an in-room planning imaging at the moment of the applicator insertion has an impact on patient’s perception in terms of comfort. Regarding the image quality concerns, further investigations are required to identify the optimal clinical practice for obtaining good image quality at a reasonable radiation dose.

Keywords: adaptive BT, image guidance, in-room imaging

3208

Poster Discussion Surgically Targeted Radiation Therapy (STaRT) vs. Post-operative Radiosurgery for Brain Metastasis Eyub Y AKDEMIR 1 , Ranjini Tolakanahalli 1 , Vibha Chaswal 1 , Selin Gurdikyan 1 , Robert Herrera 1 , Omer Gal 1 , Robert H Press 1 , Matthew D Hall 1 , D Jay Wieczorek 1 , Yongsook C Lee 1 , Alonso N Gutierrez 1 , Vitaly Siomin 1 , Michael W McDermott 2 , Minesh P Mehta 1 , Rupesh Kotecha 1 1 Radiation oncology, Miami Cancer Institute, Miami, USA. 2 Neurosurgery, Miami Neuroscience Institute, Miami, USA Purpose/Objective: Recurrent brain metastases (rBrM) after prior irradiation pose significant treatment challenges. While resection alone results in high local failure (LF) rates, reirradiation with traditional external beam methods results in an elevated risk of radiation necrosis (RN). This study evaluates the outcomes of rBrM managed with resection and a novel Cesium-131-based brachytherapy carrier, termed surgically targeted radiation therapy (STaRT). To contextualize, outcomes were compared to those of patients undergoing first-line, postoperative fractionated stereotactic radiosurgery (FSRS). Material/Methods: Patients with pathologically-proven rBrM underwent resection and STaRT and were compared to a consecutive cohort of patients treated with upfront postoperative FSRS. Kaplan-Meier method with log-rank test was used to compare the time to local control (LC) or RN between the cohorts. Results: Sixteen patients (n=16) underwent STaRT for 18 rBrM cavities to a prescription dose of 60 Gy to 5 mm from the cavity margin, with a median of three tiles per patient (range: 1.25–10.00). In comparison, 36 patients treated with postoperative FSRS received a median of three fractions (range: 1–5) to a total dose of 27 Gy (range: 18–30 Gy). Patient characteristics were similar for both cohorts as were median treated volumes (18.16 cc vs. 15.40 cc for STaRT vs. FSRS, respectively, p = 0.78). All STaRT patients had undergone at least one prior course of any type of cranial radiotherapy (median: 1, range: 1–3) to the same lesion and a median of one craniotomy (Range: 0-1) for any lesion. After median follow up of 19.8 and 21.7 months for the STaRT and FSRS cohort, respectively, 1-year LC rates were high and not significantly different between the two techniques (93.3% vs. 97.2%, p = 0.55). The 1-year rates of freedom from symptomatic RN were also similar (78.8% vs. 77.6%, p = 0.73). Conclusion: This study demonstrates that STaRT offers favorable RN and LC rates for rBrM patients given the re-irradiation setting in the STaRT cohort compared to the first-line postoperative FSRS patients in this comparative analysis. These findings advocate investigating STaRT as a potential first-line treatment option.

Keywords: brachytherapy, brain metastases, radionecrosis