T Stage and Pretreatment Standardized Uptake Values Predict Tumor Recurrence With 5-Fraction SABR in Early-Stage...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Five-fraction stereotactic ablative radiotherapy (SABR) is a common treatment for early-stage non-small cell lung cancer (NSCLC) near critical structures.
• Optimizing tumor control while minimizing toxicity is crucial in SABR regimens.
• Concerns exist that increasing SABR to 5 fractions might compromise tumor control outcomes.

Purpose of the Study:

• To identify clinical parameters that predict treatment failures in patients receiving 5-fraction SABR courses.
• To analyze factors influencing local, regional, and distant failure rates after SABR for NSCLC.

Main Methods:

• Ninety patients with T1-2 NSCLC were treated with either 50 Gy or 60 Gy in 5 fractions.
• Failure patterns (local, regional, distant) were modeled using cumulative incidences with death as a competing risk.
• Cox proportional hazards analysis was used to identify predictive clinical parameters.

Main Results:

• Overall survival and progression-free survival at 2 years were 75.8% and 59.3%, respectively.
• No significant difference in survival or failure rates was observed between 50 Gy and 60 Gy doses.
• T stage and pretreatment standardized uptake values (SUV) on PET scans were significant predictors of failure at 2 and 5 years.

Conclusions:

• Five-fraction SABR demonstrates effective in-field tumor control for early-stage NSCLC.
• T2 tumors and those with high fluorodeoxyglucose (FDG) uptake are associated with increased failure rates.
• These findings suggest a potential role for adjuvant therapies in high-risk cases, which are currently under investigation in phase 3 trials.