Discrepancies between biomarkers of primary breast cancer and subsequent brain metastases: an international multicenter study.
PURPOSE
Discordances between the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), expression between primary breast tumors and their subsequent brain metastases (BM) were investigated in breast cancer patients.


METHODS
We collected retrospective data from 11 institutions in 8 countries in a predefined-standardized format. Receptor status (positive or negative) was determined according to institutional guidelines (immunohistochemically and/or fluorescence in situ hybridization). The study was subject to each institution's ethical research committee.


RESULTS
A total of 167 breast cancer patients with BM were included. 25 patients out of 129 with a complete receptor information from both primary tumor and BM (ER, PR, HER2) available, had a change in receptor status: 7 of 26 (27%) ER/PR-positive/HER2-negative primaries (3 gained HER2; 4 lost expression of ER/PR); 10 of 31 (32%) ER/PR-positive/HER2-positive primaries (4 lost ER/PR only; 3 lost HER2 only; 3 lost both ER/PR and HER2); one of 33 (3%) ER/PR-negative receptor/HER2-positive primaries (gained ER); and 7 of 39 (18%) triple-negative primaries (5 gained ER/PR and 2 gained HER2).


CONCLUSIONS
The majority of breast cancer patients with BM in this series had primary HER2-enriched tumors, followed by those with a triple-negative profile. One out of 5 patients had a receptor discrepancy between the primary tumor and subsequent BM. Therefore, we advise receptor status assessment of BM in all breast cancer patients with available histology as it may have significant implications for therapy.
['Kaidar-Person|O|O|0000-0003-4023-1869', 'Meattini|I|I|', 'Jain|P|P|', 'Bult|P|P|', 'Simone|N|N|', 'Kindts|I|I|', 'Steffens|R|R|', 'Weltens|C|C|', 'Navarria|P|P|', 'Belkacemi|Y|Y|', 'Lopez-Guerra|J|J|', 'Livi|L|L|', 'Baumert|B G|BG|', 'Vieites|B|B|', 'Limon|D|D|', 'Kurman|N|N|', 'Ko|K|K|', 'Yu|J B|JB|', 'Chiang|V|V|', 'Poortmans|P|P|', 'Zagar|T|T|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D014408:Biomarkers, Tumor D001932:Brain Neoplasms D001943:Breast Neoplasms D047628:Estrogen Receptor alpha D005260:Female D015972:Gene Expression Regulation, Neoplastic D006801:Humans D017404:In Situ Hybridization, Fluorescence D008875:Middle Aged D009362:Neoplasm Metastasis D018719:Receptor, ErbB-2 D011980:Receptors, Progesterone
Biomarkers Breast cancer Brain metastases Receptors Molecular subtype