Stereotactic radiosurgery for patients with breast cancer brain oligometastases - Molecular subtypes and clinical outcomes

Abstract

background: We sought to determine the clinical outcomes of patients with breast cancer (Bc) who had undergone stereotactic radiosurgery (srs) for a limited number of brain metastases (BM) and to identify factors influencing overall survival (Os) and local control. Materials and methods: The records of 45 patients who underwent srs for 72 brain lesions were retrospectively evaluated. statistics included the chi-squared test, Kaplan-Meier method, and the multivariate cox model. results: The median number of treated BM was 2 (range 1-10). Median Os from BM diagnosis and post-srs were 27.6 [95% confidence interval (cI): 14.8-40.5) and 18.5 months (95% cI: 11.1-25.8), respectively. One-year and two-year survival rates after BM diagnosis were 55% and 41%, respectively. In a univariate analysis, the Luminal-B-human-epidermal-growth-receptor-positive (her2+) subtype had the longest median Os at 39.1 months (95% cI: 34.1-44.1, p = 0.004). In an adjusted analysis, grade 2 [hazard ratio (hr): 0.1; 95% cI: 0.1-0.6, p = 0.005), craniotomy (hr: 0.3; 95% cI: 0.1-0.7; p = 0.006), and ≥ 2 systemic therapies received (hr: 0.3; 95% cI: 0.1-0.9, p = 0.028) were associated with improved Os. One-year and two-year intracranial progression-free survival rates were 85% and 63%, respectively. Four factors for a higher risk of any intracranial recurrence remained significant in the adjusted analysis, as follows: age < 50 years (hr: 4.2; 95% cI: 1.3-36.3; p = 0.014), grade 3 (hr: 3.7; 95% cI: 1.1-13.2; p = 0.038), her2+ (hr: 6.9; 95% cI: 1.3-36.3; p = 0.023), and whether the brain was the first metastatic site (hr: 4.7; 95% cI: 1.6-14.5; p = 0.006). conclusion: Intrinsic Bc characteristics are important determinants for both survival and intracranial control for patients undergoing srs for oligometastatic brain disease.