Clinical outcomes and prognostic factors in HER-2 positive breast cancer with brain metastasis: A single-center experience.

e13015 Background: Brain metastasis is common in HER2 positive metastatic breast cancer patients. There is limited data on the prognosis, incidence, treatment, risk factors and complications of brain metastasized breast cancer because most clinical trials excluded these patients. we aimed to determine the characteristics and prognosis of brain metastasized HER2 positive breast cancer in our patient group, retrospectively. Methods: We scanned 3100 patients retrospectively and included 105 patients who met the criteria for inclusion in the study. Patients older 18 years old, had HER2 positive breast cancer and brain metastasis with no secondary malignity participated in the study. Results: In total, 35 (33.3%) patients had de-novo metastasis. Median overall survival (OS) was found to be 50 months in all patients. Median OS was 31 and 66 months for patients with de-novo metastasis (without brain metastasis) and patients with no metastasis at the time of the diagnosis, respectively (p < 0.01). When we compared median OS between 25 patients with one brain metastasis and 80 patients with multiple brain metastasis, it was found to be 90 months in the first-mentioned group whereas it was determined to be 45 in the latter group (p < 0.01). In all patients, the median elapsed time for the occurrence of brain metastasis was 22 months (for de-novo metastasis 15 months, for no metastasis 35 months; p < 0.01). Median OS was determined to be 15 months for all patients with brain metastasis after the occurrence of the metastasis. Patients with ECOG PS score of 0-1 at the time of the brain metastasis had 19 months median OS, while patients with ECOG PS score of 2 at the time of the brain metastasis had 8 months median OS (p < 0.01). Median OS after brain metastasis was 32 and 14 months for patients with one brain metastasis and patients with multiple brain metastasis, respectively (p < 0.01). Multivariate cox regression analyses revealed that elapsed time for the occurrence of brain metastasis was shorter in patients with high-grade tumours compared to patients with low-grade tumours (p = 0.04), and in patients with de-novo metastasis compared to patients without de-novo metastasis (p < 0.01). Conclusions: Our study indicated that tumour grade and de-novo metastasis are independent predictive factors that may cause the earlier occurrence of brain metastasis and affect mortality in breast cancer patients. After the occurrence of brain metastasis, lower ECOG PS score and multiple brain metastasis at the time of the diagnosis affected median overall survival as bad prognostic factors.