S986
Clinical - Oligometastatic cancer
ESTRO 2026
2016-2023 (8-10 Gy/fraction)1. In this same population, patients with ≥ 3 post-treatment CTs and ≥ 3 months of radiological follow-up were included. Treated adrenals were manually delineated on each CT to compute volumes and maximal diameters. Radiologic response was assessed per RECISTv1.1 as complete (rCR), partial (rPR), stable (rSD) or progressive (rPD). Associations between response and baseline variables (tumor size, histology, metastatic presentation, systemic therapy, dosimetry) or interfraction changes were explored using logistic regression and Kruskal-Wallis tests. Kaplan-Meier estimates described overall survival (OS) and local control (LC). Results: Forty-nine patients (52 adrenals; 87% treated with 50 Gy) were included. Median radiological follow-up was 33.6 months (IQR 18.3-42.8), with a median of 7 CTs per patient (IQR 4-10). Median OS was 45.6 months (95% CI 33.8-NR). LC at 1/2/3 years was 91.7%, 88.9%, and 79.0%. At last follow-up, rCR/rPR/rSD/rPD rates were 28.9%, 36.5%, 17.3% and 17.3%. Respective numbers at 3/12/24 months and their evolutions are shown in Figure 1.
the two techniques showing a trend toward statistical significance (p=0.08). (Figure). Metastasis-free survival (MFS) at 12-, 24- and 36-months in CK and TT group was 29.4% vs 35.1%, 20.0% vs 21.8% and 16.0% vs 19.6%, respectively. Overall survival (OS) at 12-, 24- and 36-months in CK and TT group was 70.6% vs 75.0%, 47.8% vs 49.4%, and 41.0% vs 40.4%, respectively. Similar acute (mainly pain and vomit G1) and late (G ≥ 2 actinic pneumonitis and erythema) toxicities were observed in both groups.
Conclusion: In our experience both techniques achieved good local control, with a trend in favor of robotic treatment. This is probably due to the submillimeter precision of the continuous tracking that allow to prescribe a BED> 100
Gy to a larger proportion of lesions. Keywords: Liver metastasis, SBRT
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Median time to rPD was 23.0 months (IQR 11.1-31.6). Most tumors regressed early, with a median 3-month volume reduction of 50.8% (IQR 33.9-75.7) versus start-of-treatment; 94% of lesions decreased at 3 months, 83% by >20%. No baseline clinical or dosimetric factor predicted rPD. Similarly, interfraction change patterns (increasing/decreasing/rebound) and early post-treatment dynamics were not predictive of late progression, suggesting that transient in- treatment variations do not reflect long-term response. In contrast, smaller absolute volumes at baseline (p=0.038) and end-of-treatment (p=0.044), as well as smaller maximal diameters at 3 months (p=0.018), were associated with rCR. However, 3- month adrenal volume itself was not predictive of eventual progression: when grouped by RECIST category at last follow-up, rCR/rPD lesions showed similarly small 3-month volumes, distinct from the rPR/rSD groups (Figure 2). A trend toward improved OS was observed for rCR patients (p=0.11).
Long-term RECIST and volumetric responses after 5-fraction stereotactic ablative radiotherapy for adrenal metastases Nicolas Giraud 1,2 , John R. van Sornsen de Koste 1 , Miguel A. Palacios 1 , Famke L. Schneiders 1 , Suresh Senan 1 1 Radiation Oncology, Amsterdam UMC location Vrije Universiteit Amsterdam, Amsterdam, Netherlands. 2 Radiation Oncology, CHU Bordeaux, Bordeaux, France Purpose/Objective: Stereotactic ablative radiotherapy (SABR) is increasingly used for adrenal oligometastases, yet long-term radiological data are lacking. We investigated long-term volumetric and radiological evolution after adrenal SABR to characterize response dynamics and identify predictors of durable control. Material/Methods: We previously reported frequent and unpredictable interfraction volumetric changes during adrenal MR- SABR in 66 patients treated with 5-fraction between
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