Stereotactic radiotherapy of the tumor bed compared to whole brain radiotherapy after surgery of single brain metastasis: Results from a randomized trial.

PURPOSE: To evaluate if neurological/cognitive function outcomes in patients with resected single brain metastasis (BM) after stereotactic radiotherapy of the tumor bed (SRT-TB) are not inferior compared to those achieved with whole-brain radiotherapy (WBRT).

METHODS: Patients with total/subtotal resection of single BM were randomly assigned either to SRT-TB (n=29) or WBRT (n=30). SRT-TB arm consisted of 15Gy/1 fraction, or 5×5Gy. WBRT consisted of 30Gy/10 fractions. Neurological/cognitive failure was defined as a decrease of neurological score by one point or more, or a worsening of the MiniMental test by at least 3 points, or neurological death. Cumulative incidence of neurological/cognitive failure (CINCF), neurological death (CIND), and overall survival (OS) were compared.

RESULTS: Median follow-up was 29months (range: 8-45) for 15 patients still alive. The difference in the probability of CINCF at 6months (primary endpoint) was -8% in favor of WBRT (95% confidence interval: +17% -35%; non-inferiority margin: -20%). In the intention-to-treat analysis, two-year CIND rates were 66% vs. 31%, for SRT-TB and WBRT arm, respectively, p=.015. The corresponding figures for OS were 10% vs. 37%, p=.046.

CONCLUSIONS: Non-inferiority of SRT-TB was not demonstrated in our underpowered study. More data from randomized studies are needed for confirmation of the value of this method.