With the development of new human epidermal growth factor 2 (HER2)‐targeting therapies, a non‐invasive method of determining the HER2 status of breast cancer brain metastases can be of great clinical value, particularly given the risks of brain biopsy and the possibility of discordance between HER2 status of the primary breast cancer and the brain metastasis. Here, ERBB2 is linked to breast cancer.