Biologically effective dose (BED) value lower than 120 Gy improve outcomes in lung SBRT.

Background: Lung SBRT has a well-defined role in the treatment of patients with early stage non-small cell lung cancer who are not surgical candidates or refuse surgery. Biologically effective dose (BED) of greater than or equal to 100 Gy has been recommended. However, optimal fractionation remains unclear. Our objective was analyze patients treated with lung SBRT in our institution and evaluate outcomes according prescribed dose.

Patients And Methods: One hundred nine patients with early non-small cell lung cancer and treated with lung SBRT were retrospectively analyzed. Differences between dose received, local control, and survival were evaluated. For comparison of BEDs, the prescribed dose for SBRT was stratified according to two groups: high (BED > 120 Gy) and low (BED < 120 Gy).

Results: A relationship between mortality and total dose (54.7 Gy ± 4.8) was observed. Significantly worse survival was observed for patients with higher total doses (p < 0.003). It was found that patients receiving BED > 120 had increased mortality compared to patients receiving BED < 120 (p = 0.021). It was observed mean dose/fraction 12.6 Gy/f was a protective factor and decreased the probability of death.

Conclusion: Our data suggest that mean total dose lower 54 and a calculated BED < 120 Gy is the optimal. Further prospective data are needed to confirm these results and determine the optimal dose fractionation scheme as a function of tumor size and location of volume.