The arrival of subsequent generations of tyrosine-kinase inhibitors (TKIs) has significantly broaden the EGFR-mutated lung cancer therapeutic landscape. Results from the FLAURA clinical trial have pushed osimertinib to the first-line treatment for patients with advanced-stage disease, showing outstanding control rates of intracranial metastases, considerably higher than those of the first and second-generation EGFR TKIs. A progressively better knowledge of short and long-term neurocognitive side effects of radiotherapy, as well as the lack of evidence about the benefit of its combination with TKIs, has opened a debate about its indication at diagnosis of intracranial disease, at least before the response to targeted therapy has been evaluated. However, there is a small percentage of primarily resistant cases to osimertinib, mainly due to histologic transformation, acquired EGFR mutations and off-target genetic resistances that lead to a scenery of poor clinical prognosis in which radiotherapy may have a higher relevance for the management of brain metastases. We offer a review of the current recommendations for the management of intracranial metastases in EGFR-mutated NSCLC and the resistance mechanisms to third-generation TKIs, following the report of an unusual clinical case with a rapid progression to osimertinib.