Single- Versus Multi-Fraction Stereotactic Body Radiotherapy for Primary Lung Cancer and Pulmonary Oligometastases: A...

Stereotactic body radiation therapy (SBRT), the standard of care for medically inoperable early-stage NSCLC, is increasingly used for pulmonary oligometastases. Optimal fractionation-single fraction (SF) versus multiple fractions (MF)-remains unclear, as existing randomized studies lack power to confirm SF noninferiority in local control. This review assessed 2-year local failure (LF) rates for SF versus MF SBRT. PubMed, Ovid Medline, and the Cochrane Library were searched. Titles and abstracts were reviewed followed by full-text review. Studies reporting LF outcomes for SF or MF SBRT in early-stage NSCLC or pulmonary metastases were included. Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Cochrane Handbook for Systematic Reviews guidelines were followed. Pooled estimates were calculated using fixed- and random-effects models. Primary lung cancers treated with biologically effective doses (BED₁₀) ≥100 Gy demonstrated similar 2-year LF rates with SF and MF SBRT. However, unclear T1/T2 classification may contribute to selection bias, as MF is often used for larger tumors. SF SBRT was associated with an 8.25% higher LF rate in cohorts treated with BED₁₀ <100 Gy. Pulmonary metastases treated with SF demonstrated a 4% higher LF rate compared with MF, although substantial heterogeneity limited confidence in this finding. Limited data demonstrated the highest 2-year LF rates (25.6%) in colorectal oligometastases. Overall, SF SBRT appears to provide similar 2-year LF outcomes to MF in primary lung cancer when adequate BED is delivered, although cautious guideline application is warranted given the predominance of retrospective studies and limited data for larger or radioresistant tumors. MF may offer modest benefit for pulmonary metastases.