Prognostic factors, patterns of failure and re-irradiation in hypofractionated stereotactic radiotherapy-treated brain metastases from non-small cell lung cancer.

Background: Hypofractionated stereotactic radiotherapy (fSRT) is increasingly used for brain metastases (BMs) from non-small cell lung cancer (NSCLC). However, relevant data concerning treatment outcomes of fSRT and clinical utility of re-irradiation using fSRT (re-fSRT) remain scarce.

Methods: Consecutive NSCLC patients with fSRT-treated BMs from May 2018 to May 2022 were included. The cumulative incidence of intracranial local recurrence (iLR), intracranial progressive disease (iPD) and symptomatic radiation necrosis (sRN) were calculated from the initiation of fSRT, choosing death as the competing event. Patients with limited iPD (number ≤5 and size ≤3 cm) and without iLR developed within 12 months, were classified as re-fSRT candidates. The clinical value of re-fSRT and dosimetric predictors of sRN were investigated.

Results: With a median follow-up of 22.3 months, the 1-year, 2-year and 3-year cumulative incidence of iLR among the 218 identified patients were 8.1 %, 12.3 %, 17.8 %, respectively. Biological effective dose, total tumor volume and concurrent systemic therapy were associated with the risk of iLR. Notably, 45 (76.3 %) of the 59 patients with iPD were feasible for re-fSRT. Re-fSRT was performed in 19 (42.2 %) of the 45 candidates and associated with improved survival ( = 0.010). The 1-year, 2-year and 3-year cumulative incidence of sRN in the whole population were 4.5 %, 10.3 %, 17.7 %, respectively. Moreover, sRN occurred in 3 (15.8 %) patients receiving re-fSRT and Brain V20Gy was found to be associated with the risk of sRN.

Conclusion: fSRT is a promising treatment for limited BMs from NSCLC and some patients may benefit from re-fSRT.