Single-fraction lung SBRT achieved 100% estimated one-year local control in selected patients

KEY POINTS

• This single-institution retrospective analysis used prospectively collected data from 49 inoperable patients with 50 lung lesions treated from August 2023 onward. Median age was 77 years; 30 lesions (60%) were primary NSCLC and 20 (40%) pulmonary metastases.
• Patients had small selected lesions: median maximum diameter was 1.9 cm, central/ultracentral targets were excluded, and oligometastatic patients had no more than three pulmonary metastases. The cohort was clinically frail: almost all had comorbidity, including substantial cardiovascular and respiratory disease.
• Single-fraction SBRT was delivered with helical tomotherapy at a median 27 Gy (IQR 26–28 Gy), corresponding to median BED10 100 Gy. The treatment session was divided into two mini-fractions with image verification, and median treatment-slot duration was approximately 22 minutes.
• Technical feasibility was 50/50 lesions (100%; 95% CI 92.9–100%): no treatment required interruption, replanning, conversion to multifraction treatment or abandonment.
• Among 44 evaluable patients, 93.2% had no acute adverse event; three developed thoracic pain, all grade 1–2. Late grade 1 pneumonitis occurred in 5/44 patients (11.4%), and no grade ≥3 acute or late toxicity was recorded.
• Metabolic response was substantial among 27 lesions with paired PET assessment: median SUVmax decreased from 9.5 to 2.8 (p<0.001). This is a surrogate response measure and does not replace longer-term local-control assessment.
• At median follow-up of only 13.7 months, one of 50 lesions had locally recurred. Estimated 12-month local control was 100%, distant progression-free survival 89.4% and overall survival 89.5%; six patients experienced distant progression and three died during follow-up.

CLINICAL TAKEAWAY

SOURCE

Frontiers in Oncology