Multiplicity does not significantly affect outcomes in brain metastasis patients treated with surgery.

Background: Brain metastasis quantity may be a negative prognostic factor for patients requiring resection of at least one lesion.
Methods: We retrospectively reviewed patients who underwent surgical resection of brain metastases from July 2018 to June 2019 at our institution, and examined outcomes including overall survival (OS), progression free survival (PFS), and rates of local failure (LF). Patients were grouped according to the number of metastases at the time of surgery (single vs multiple).
Results: We identified 130 patients who underwent surgical resection as the initial treatment modality. At the time of surgery, 87 patients had only one lesion (control) and 43 had multiple (>1). Two-year OS for the entire cohort was 46%, with equal rates in both the multiple metastases group and the control group ( P = .335). 2-year PFS was 27%; 21% in the multiple metastases group and 31% in the control group ( P = .766). The rate of LF at 2 years was 32%, with equal rates in both the multiple lesion group and control group ( P = .889). On univariate analysis, multiplicity was not significantly correlated to OS (HR = 0.80, 95% CI: 0.51-1.26, P = .336), PFS (HR = 1.06, 95% CI: 0.71-1.59, P = .766) or LF (HR = 1.06, 95% CI: 0.57-1.97, P = .840). Multivariate analysis revealed preoperative tumor volume of the resected lesion to be the single correlate for OS ( P = .0032) and PFS ( P = .0081).
Conclusions: Having more than one metastasis does not negatively impact outcomes in patients treated with surgery. In carefully selected patients, especially those with large tumors, surgery should be considered regardless of the total number of lesions.
(© The Author(s) 2022. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)