2454 - Efficacy and Safety of Moderate-Dose SBRT for Patients with Oligometastatic Lung Cancer Ineligible for Standard SBRT

Purpose/Objective(s): Stereotactic body radiation therapy (SBRT) is increasingly being integrated into the management of oligometastatic lung cancer, showing promising local control and potential survival benefits. However, SBRT is not feasible for all patients, particularly when oligometastatic lesions are adjacent to critical organs or when patients have poor performance status. In this setting, moderate-dose SBRT could be considered as an alternative to achieve sustained local control while minimizing toxicity. This study aims to evaluate the efficacy and safety of moderate-dose SBRT in patients with oligometastatic lung cancer who are unfit for SBRT.

Materials/Methods: A retrospective analysis was conducted. Eligible patients received moderate-dose SBRT with 25–36 Gy in 4–6 fractions for oligometastatic lung cancer, including oligometastases or oligoprogression, between October 2024 and April 2024 at a single institution. The primary endpoint was local control (LC). Progression-free survival (PFS), disseminated disease-free survival (DDFS), overall survival (OS), and toxicities were analyzed. Disseminated disease was defined as disease progression with more than five new or progressive metastases occurring simultaneously.

Results: A total of 38 patients treated for 49 oligometastatic lesions from lung cancer were included. Non-small-cell lung cancer was the predominant histologic type (63.1%). The most commonly treated metastatic sites included regional lymph nodes (49.0%), distant lymph nodes (20.4%), lung (18.4%), adrenal glands (8.1%), and chest wall (4.1%). The most common SBRT regimen was 35 Gy in 5 fractions (69.4%) and 30 Gy in 5 fractions (20.4%). The median follow-up was 15 months (range, 3.2–54.0 months). The cumulative LC rate at 12 and 24 months was 88.5% (95% CI, 10–22) and 85.2% (95% CI, 30–46.7); PFS was 47.9% and 18.8%, DDFS was 74.9% and 55.4%, and OS was 83.5% and 55.0%, respectively. The most common toxicity was radiation pneumonitis (10.2%). No grade 3 or higher toxicities were observed.

Conclusion: Moderate-dose SBRT provided favorable local control rates with a favorable toxicity profile in patients with oligometastatic lung cancer who are unfit for standard SBRT. These findings suggest that moderate-dose SBRT could be an option for patients with poor performance status or tumors adjacent to critical organs.