Survival time and prognostic factors after whole-brain radiotherapy of brain metastases from of breast cancer

BACKGROUND: Breast cancer has a poor prognosis due to the high risk of distant metastasis. PURPOSE: To identify the prognosticators of brain metastasis from breast cancer treated by whole-brain radiotherapy. MATERIAL AND METHODS: We evaluated patients diagnosed with primary brain metastasis without carcinomatous meningitis from breast cancer and had undergone whole-brain radiotherapy as initial treatment between 1 January 2010 and 30 September 2019. We investigated associations between overall survival time from diagnosis using cranial contrast-enhanced magnetic resonance imaging (MRI)/computed tomography (CT) and the following parameters: (i) age; (ii) sex; (iii) time to appearance of brain metastasis; (iv) other metastasis at appearance of brain metastasis; (v) blood test; (vi) symptoms at time of brain metastasis; (vii) whole-brain radiotherapy dose; (viii) whether whole-brain radiotherapy was completed; (ix) course of chemo- or radiotherapy; (x) subtype; (xi) additional irradiation after whole-brain radiotherapy; (xii) pathology; and (xiii) imaging findings. RESULTS: We evaluated 29 consecutive female patients (mean age 55.2 ± 12.1 years). Median overall survival time after diagnosis on cranial contrast-enhanced MRI/CT was 135 days (range 16–2112 days). Multivariate stepwise analysis of the three parameters of lactate dehydrogenase, dose, and subtype identified the following significant differences: Hazard Ratio (HR) for dose (discontinued, 30 Gy/10 fractions, 31.5 Gy/11 fractions, 32.5 Gy/11 fractions, 37.5 Gy/15 fractions) was 0.08 (95% confidence interval [CI] 0.02–0.30, P < 0.01), and HR for subtype (luminal, HER2, triple-negative) was 2.70 (95% CI 1.16–6.243, P < 0.01). CONCLUSION: HER2-type and 37.5 Gy/15 fractions are good prognostic factor after whole-brain radiotherapy in breast cancer with brain metastases.