This case reports a 52-year-old woman diagnosed with IBC of 119x89mm, axillar node-positive, hormone receptor-negative, HER2 positive.... After two cycles of T-DM1, the patient was asymptomatic, and no lesions were seen on the radiotherapy planning CT scan. Cranial MR showed a reduction in the size of the lesions (9x8 mm and 4 mm) and in the vasogenic edema (Figure 2), so it was decided not to undergo radiotherapy given the good response to TDM-1 therapy.