Survival Outcomes of Stereotactic Radiotherapy for Ten or More Brain Metastases

Abstract

Abstract AIMS Discrepancies exist in the use of stereotactic radiotherapy (SRT) for patients with 10 or more brain metastases. Concerns include multiple metastases being associated with poor survival and the lack of prospective data. We analysed survival outcomes of these patients in a multi-centre cohort. METHOD We performed a retrospective cohort study of 511 consecutive patients from three SRT centres treated for brain metastases between January 2010 - August 2021, censored in January 2022. We assessed survival post-SRT of patients with ≥10 metastases against a matched group of 5-9 and 1-4 metastases using the logrank test for statistical testing. We used a multivariate Cox model to assess the relationship between overall survival and: number of metastases; total volume; primary malignancy; use of systemic anti-cancer therapies with intracranial penetrance; controlled extracranial disease. Results with p-values <0.05 were considered significant. RESULTS Survival data was available for all patients, and for 85-100% of factors in multivariate analysis. 63 patients had ≥10 metastases (median 19). Median survival was 13.3 months, compared with 15.1 and 19.0 months for the 5-9 and 1-4 metastasis groups respectively. Differences were not statistically significant (p-value 0.14). Increasing volume of disease (HR 1.05 [1.01-1.09], p-value: 0.01), non-small cell lung cancer (HR 3.5 [1.35-9.09] p-value: 0.01) and use of systemic anti-cancer therapy with intracranial penetrance (HR 0.239 [0.105-0.547] p-value: <0.01) had a statistically significant effect on survival in multivariate analysis. CONCLUSION Carefully selected patients with multiple metastases have acceptable survival outcomes following SRT and this approach should be more widely considered.