Brain metastasis in patients with metastatic breast cancer in the real world: a single-institution, retrospective review of 12-year follow-up.

PURPOSE: The data of 589 metastatic breast cancer (MBC) patients in a single institution were reviewed to determine the outcomes of patients with brain metastasis (BM) and assess the efficacy of BM screening.

METHODS: The patients with BM among the 589 MBC patients who underwent treatment at Shizuoka Cancer Center (Shizuoka, Japan) from 09/2002 to 03/2014 were retrospectively analyzed.

RESULTS: During the study period, BM developed in 187 (31.7%) patients. The tumor subtypes were as follows: luminal (hormone receptor [HR]+, HER2-), 44.9%; luminal-HER2 (HR+, HER2+), 14.9%; HER2 (HR-, HER2+), 21.3%; and triple-negative (TN), 16.0%. BM was detected in 48.6% of the patients by screening MRI. While 137 of 187 patients underwent local therapy, whole-brain irradiation was the most frequently applied therapy (63.5%). The median overall survival from the diagnosis of BM was as follows: luminal, 7.0 months (M); luminal-HER2, 13.3 M; HER2, 17.7 M; TN, 4.2 M. The HER2 status (hazard ratio [HR]: 0.58, 95% confidence interval [CI] 0.38-0.88) and nonprogressive extracranial lesion(s) (HR: 0.45, 95% CI 0.29-0.71) were identified as prognostic factors in a multivariate analysis. When limited to HER2-overexpressed MBC patients, the multivariate analysis revealed that non-progressive extracranial lesion(s) (HR: 0.20, 95% CI 0.088-0.47) and stereotactic irradiation (STI) as an initial treatment (HR: 0.18, 95% CI 0.061-0.56) were prognostic factors.

CONCLUSIONS: Our retrospective review showed that early detection of BM by screening MRI, followed by STI, improved the prognosis of HER2-overexpressed MBC patients with BM. A further prospective randomized study is needed to confirm our findings.