Most frequently occurring in patients with non-small cell lung cancer (NSCLC), melanoma and human epidermal receptor 2 positive (HER2) and invasive lobular carcinoma subtypes of breast cancer,1,2 they can develop in up to 26% of all patients who die from cancer.3 Additionally, with improvements in survival and systemic disease control over the last few decades,4–6 alongside more sensitive imaging techniques allowing the identification of even smaller brain metastases,7 there has been a significant increase in the identification of brain metastases,1 including asymptomatic brain metastases. Here, ERBB2 is linked to non-small cell lung carcinoma.