HER2 significance and treatment outcomes after radiotherapy for brain metastases in breast cancer patients.

The aim of this retrospective study was to examine the influence of HER2 status on outcome in breast cancer patients following whole brain radiotherapy (WBRT) for cerebral metastases. One hundred and eighty one patients with recordable HER2 status, who received WBRT at single institution were identified and stratified according to HER2 status. Eighty eight were HER2 positive (HER2+) (49%) and 93 HER2 negative (HER2-) (51%). A total of 72 (82%) HER2+ group developed brain metastases whilst on chemotherapy compared with 45 (48%) in HER2- group. Median survival after WBRT was 8 months (1-38) for HER2+ patients and 4 (1-64) for HER2- patients p=0.01. On brain metastasis progression, 18 (20%) of HER2+ patients received further local therapy compared with 6 (6%) in HER2- group. This study shows superior survival in HER2+ group following WBRT as compared to HER2- group and more aggressive management on disease progression in HER2+ group.