From protocol to practice: long-Term outcomes of single-Fraction stereotactic body radiotherapy for primary non-Small cell lung cancer.

Background: Single-fraction stereotactic body radiotherapy (SBRT) is an effective treatment option for patients with non-small cell lung cancer (NSCLC) who are ineligible for surgery. This study investigates long-term clinical outcomes, prognostic factors, and toxicity associated with high-dose single-fraction SBRT.

Materials and methods: We retrospectively analyzed 110 patients with 116 NSCLC lesions treated with single-fraction SBRT between 2000 and 2023. Histologic subtypes included adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and CT-defined suspicious lesions without histological confirmation. Local control (LC), progression-free survival (PFS), and overall survival (OS) were assessed using Kaplan-Meier and Cox regression models. Toxicity was evaluated using CTCAE v4.0.

Results: The most common dose was 30 Gy, prescribed in 76.7% of lesions. Among patients who received ≥ 30 Gy, LC at 2, 3, and 5 years was 78%, 74%, and 68%; PFS was 63%, 49%, and 37%; and OS was 84%, 83%, and 60%, respectively. LC and PFS were significantly higher in patients treated with ≥ 30 Gy (p < 0.05). Acute pneumonitis occurred in 2 patients (1.8%), and 22 patients (20.0%) developed late-onset pneumonitis. Pneumonitis incidence was 26.8% in patients planned with 3D-CT, compared to 12.8% with DIBH or 4D-CT. No grade ≥ 3 toxicity was observed.

Conclusion: High-dose (≥ 30 Gy) single-fraction SBRT provides excellent long-term tumor control with minimal toxicity with NSCLC. Advanced motion management techniques were associated with reduced pulmonary toxicity. A ≥ 30 Gy dose significantly improved LC, PFS, and OS. Higher Charlson Comorbidity Index (CCI) was associated with worse OS. These findings support the use of high-dose SF-SBRT in selected patients and highlight the need for individualized treatment planning. Prospective validation is warranted.