ESTRO 2024 - Abstract Book

S1696

Clinical - Lung

ESTRO 2024

A total of 87 patients were identified with a median age of 70 years (range 34-91); 70% had a primary lung tumor and 30% a metastatic lung lesion. Co-existing interstitial lung disease (ILD) was present in 6% of patients. Median breath-hold GTV was 10.2 cc (range 0.6-140.4) and median PTV was 24.6 cc (range 4.2-220.4). The GTV was located ≤1 cm from trachea -main bronchi (HILUS study group A) in 9% of patients, and 24% had a GTV >1 cm from the trachea or main bronchi but ≤1 cm from the intermediate or lobar bronchi (HILUS group B) (Figure 1). Most lesions were treated using either 8 fractions of 7.5 Gy (56%) or 5 fractions of 11 Gy (35%). At a median follow-up of 41 months, the median overall survival was 38 months (95% CI 28-48) for all patients. The local recurrence rate was 10% for all patients, ranging from 7% for primary lung tumors and 19% in patients treated for metastases. Almost all recurrent metastatic lung tumors were from colorectal disease (n = 4), and the remaining patient was treated for a melanoma metastasis (n = 1). The local progression-free survival at 2 years was 88% for all patients, ranging from 82% for patients treated for lung metastases, and 91% for a primary lung tumor (Figure 2). Salvage surgery was performed in 4 patients with a local recurrence (44%). After a median follow- up time of 38 months, grade ≥3 clinical toxicity was observed in 6 patients (7%), all manifesting ≤18 months post -SABR. The toxicity-free survival at 2 years was 91%, with 67% of patients in this group having a tumor located within 1 cm from the lobar bronchi (Figure 2). Nearly 50% of grade ≥3 toxicities were due to respiratory symptoms arising from bronchial stenosis or atelectasis. One fatal toxicity was observed (1%) following exacerbation of an ILD at 1 month post-SABR in a patient with a HILUS B lesion.