Purpose/Objective(s): Single-fraction stereotactic ablative body radiation (SF-SABR) has been recognized in consensus guidelines as a treatment option for Stage I non-small cell lung cancer (NSCLC). However, concerns regarding toxicity and local control have limited its use. We present data on toxicity and disease control from our institution’s SF-SABR experience delivering up to 34 Gy for peripheral NSCLC. We hypothesized that the SF-SABR long-term toxicity profile and oncological outcomes are comparable to traditional fractionated approaches. Materials/
Methods: We conducted a retrospective review of 203 consecutive patients treated with SF-SABR for a total of 230 NSCLC lesions between May 16, 2018, and May 31, 2023. Patients had a minimum follow-up of 6 months. We analyzed patient and cancer characteristics, physician-reported toxicity, site of relapse, progression-free survival (PFS), cancer-specific survival (CSS) and overall survival (OS). Research ethics board approval was obtained for this study. Survival rates were assessed using Kaplan-Meier curves, and subgroup comparisons were made using the log-rank test. Results: The median [IQR] follow-up duration for the 203 patients enrolled in the study was 28.1 months [20.3-35.9]. The median age was 74 [68-79] years. Lesions analyzed comprised stage I-II (91.3%) and oligometastatic disease (8.7%). Pathological diagnosis was obtained in 30.6% of cases. Reasons for omitting biopsy included poor pulmonary function tests (39.8%), patient refusal (13.3%) and other reasons (46.9%). Median tumor size was 1.4 cm (range 0.5-4.2 cm). Doses administered were < 30 Gy (13.5%), 30 Gy (54.8%), or 34 Gy (31.7%). Ninety-one lesions (40.6%) had an ITV located = 0.5 cm from the chest wall. Chest pain was reported in 10.5% of cases, with only 4.5% classified as grade 2 and no grade 3 or higher. Rib fractures occurred in 3.2% of cases. Lung toxicities were limited to 3.2% grade 2 and 0.9% grade 3, with no grade > 3 treatment-related toxicities. Two-year local, regional, and distant control rates were 94.0%, 94.8%, and 93.3%, respectively. Median PFS was 39.2 months, with 2-year PFS, OS, and CSS rates of 66.7%, 75.0%, and 85.6%, respectively. Predictors of local control were low SUV max (p = 0.05), and dose = 30 Gy (p = 0.008) but no difference was found between 30 and 34 Gy (p = 0.4). The percent of local recurrence for lesions receiving < 30 Gy, 30 Gy and 34 Gy were respectively 19%, 3% and 5.7%. Local control did not significantly vary with tumor location, biopsy-proven status or histology. Conclusion: This 5-year experience confirms previously published data suggesting that SF-SABR for peripheral NSCLC is a suitable treatment option with a favorable toxicity profile and effective disease control. It highlights the significance of a dose of at least 30 Gy to optimize the likelihood of local control. The low rate of pathological diagnosis of cancer may have contributed to the favorable oncological outcomes observed.
