S981
Clinical - Oligometastatic cancer
ESTRO 2026
Digital Poster 3499 Liver stereotactic body radiotherapy in oligometastatic disease: 10 years of institutional experience Miguel Catalo, Dora Gomes, Isabel Rodrigues, João Silva, Eduardo Rocha, Bárbara Castro, Olga Sousa External Radiation Therapy Department, Instituto Português de Oncologia do Porto Francisco Gentil, Porto, Portugal Purpose/Objective: Oligometastatic disease, an intermediate state between localised and disseminated malignancy, is considered amenable to metastasis-directed aggressive therapy, improving long-term survival. [1] The liver is a frequent metastatic site [2]. While surgery is the standard for hepatic oligometastases, stereotactic body radiotherapy (SBRT) is an alternative for patients ineligible for surgery [3], aiming to optimise survival and defer further systemic therapy. This study sought to characterise patients undergoing hepatic SBRT for oligometastatic disease at one institution and to assess survival and toxicity outcomes. Material/Methods: This retrospective cohort observational study included patients treated with SBRT for hepatic oligometastases from 2014 to 2024 in our institution. Our team collected data from clinical records, conducted a descriptive analysis and evaluated survival outcomes using Kaplan-Meier curves and Cox-regression model. Results: 49 patients (57.1% male, median age 66 years, range 39–89) with 63 lesions were treated. Primary tumours were most often colorectal (n=46; 73%), followed by breast (n=10; 15.9%), lung (n=3; 4.8%), and others (n=4; 6.3%). Median follow-up time was 20 months (1-128). 34 patients (69.4%) had prior systemic treatment, with stable disease in 15 (44%) and partial response in 17 (50%); 2 (6%) had progression. Median lesion diameter was 22 mm (4–70), and median ITV 14 cc (0.1–85). Lesions were treated with 50Gy/5 fractions (fr) (n=28; 44.4%), 60Gy/3fr (n=19; 30.2%), 45Gy/3fr (n=10; 15.9%), 45Gy/5fr (n=5; 7.9%) and 42,5Gy/5fr (n=1; 1.6%). At 3 months post-RT, 23 lesions (36.5%) were stable, 19 (30.2%) had complete response and 15 (23.8%) had partial response. Early evaluation precluded assessment in 6 lesions (9.5%). Local progression occurred in 13 lesions (20.6%). 2-year local progression-free survival was 68.8%. BED10>100Gy was associated with better local control (LC) (90% vs. 47%, Log-Rank 13,2; p<0,001). Larger Internal target volumes (ITVs) related with reduced LC (HR = 1.024, 95% CI 1.003–1.046). Distant progression was seen in 30 patients (61.2%), mainly in the liver (n=23; 76.7%), lymph nodes (n=9; 30%), or lung (n=8; 26.6%). 2-year
Severe adverse events were rare (grade ≥ 3: adrenalectomy 1.6%, 30-day mortality 1.3%; SABR 0.4% acute and 1.0% late, treatment-related mortality 0.2%). In SABR studies, LC showed a strong dose- response relationship, with BED10 ≥ 100 Gy predicting 95% 1-year LC (Figure 2).
Higher BED10 also correlated with improved progression-free (PFS) and 2-year overall survival (OS). Adrenalectomy achieved higher 1- and 2-year OS (81% and 61%) compared with SABR (70% and 45%), likely reflecting the predominance of solitary adrenal lesions in surgical series (70% versus 36%) and the inherently fitter surgical population eligible for resection. Use of minimally invasive surgery (MIS) and lower conversion rates were associated with improved PFS and OS. Conclusion: Both MIS adrenalectomy and dose-escalated SABR are safe and effective local therapies for adrenal metastases. Prospective comparative studies are needed to optimize patient selection and integrate both approaches in the oligometastatic setting. Keywords: Adrenal metastases; meta-analysis
Made with FlippingBook - Share PDF online