Risk stratification for unfavorable outcome after resection of selected brain metastases in patients with multiple brain metastases

OBJECTIVE: Surgical removal of brain metastases (BM) may improve patients' prognosis when substantial tumor debulking is achieved. Patients with multiple lesions may be offered surgery for symptomatic lesions or to obtain histopathologic diagnosis. There is only few evidence on risk analysis for resection of selected BMs in patients with multiple BMs. METHODS: In this bicentric study, patients with multiple BM (i.e. n ≥ 2) who underwent microsurgery for selected lesions between 2021 and 2024 were included. Demographic data, Karnofsky Performance Status (KPS), 5-item modified frailty index (mFI-5), clinical course and MR-imaging including volumetric assessment of tumor volumes were analyzed. The primary endpoint was 90-day mortality. Secondary endpoints were institutional discharge, length of inpatient stay, and allocation to adjuvant treatment. RESULTS: One-hundred-and-thirty-two patients met the inclusion criteria. Median age was 63 years (IQR 21.8) and 54 (40.9%) were female. Ninety patients (68.2%) had 2-4 BMs and 42 patients (31.8%) had ≥ 5 BMs. The median resected tumor volume was 15.4 (IQR 21.6) cm³ per patient. The 90-day mortality was 28% (37/132). Factors associated with increased 90-day mortality included advanced age (p < 0.001), lower preoperative KPS (p = 0.048), lack of adjuvant treatment (p < 0.001) and higher mFI-5 score (p = 0.008). Lower preoperative KPS (p < 0.001) and higher mFI-5 scores (p < 0.001) were significantly associated with discharge to institutional care rather than home. Length of postoperative in-hospital stay inversely correlated with KPS (rs = -0.29, p = 0.001) and positively with mFI-5 score (rs = 0.26, p = 0.003) but not with age, tumor volumes or number of lesions. CONCLUSION: In patients with multiple BM, increasing age, increased frailty and low preoperative KPS influenced 90-day mortality and short-term outcome. Resection for symptom relief or tissue diagnosis in these patients may be performed with these precautions.