ESTRO 2025 - Abstract Book

S1390

Clinical - Lung

ESTRO 2025

fraction (MF) SABR remains the treatment of choice for people with medically inoperable early-stage lung cancer, we have continued to use SF SABR for selected cases, often those with other medical conditions or frailties or those living in remote/rural locations. We wanted to investigate the efficacy of SF SABR for this real-world cohort. Material/Methods: Our pre-existing prospective institutional SABR database was used to identify patients with T1-T2N0M0 (TNM8) early-stage lung cancer treated with single-fraction SABR between 01/2019 and 12/2022. Patients with oligometastatic recurrence or synchronous lung primaries were excluded. Dose prescribed was initially 28Gy (25%) then 30Gy (75%), planned with heterogeneity correction. Clinical outcomes were extracted from our hospital electronic medical records. Institutional ethical approval was obtained. Baseline demographics, comorbidities, and lung cancer characteristics were collected. The primary endpoint was overall survival (OS). Secondary endpoints included local control, pattern of first failure, progression-free survival, cancer specific survival and treatment toxicity. Results: A total of 128 patients with early-stage lung cancer were treated with SF SABR. Most patients (46.5%) were ECOG Performance 2, 53.9% were male and 93% were Caucasian. Median age was 77 years (IQR range 69.8-82 years) and 90.5% were former/current smokers. Tissue diagnosis was preferred, however, if biopsy was unsuccessful or deemed high risk, empiric SABR was offered after MDM consensus of radiologic diagnosis; 51/128 patients (39.8%) were biopsy proven of which 30/51 (58.8%) were adenocarcinoma. 111/128 (86.7%) had a T1 tumour (≤3cm). Median OS was 43 months (IQR 19-65 months) (Figure 1), comparable to the 44-month median OS reported by the Cleveland Clinic (4). Median follow-up was 21.5 months (IQR: 12-34.5 months). No patients recorded a Grade 3 or higher SABR related adverse event and 3% had a Grade 2 event (3 rib fractures, 1 pneumonitis). At data cut-off, local failure had occurred in 17 patients, regional failure in 14 patients and distant failure in 8 patients.

Figure 1 Title: Kaplan-Meier overall survival for single-fraction stereotactic body radiotherapy

Conclusion: In our experience, single fraction SABR treatment for early-stage lung cancer is an effective and safe treatment option especially for this real world elderly cohort.

Keywords: Early-stage lung cancer, single fraction SABR