Prevention strategies for brain metastases from HER2-positive breast cancer

The incidence of brain metastases is particularly high in HER2-overexpressing (HER2+) breast cancer. Several hypotheses have been raised trying to explain this peculiar phenomenon, including a better control of extra-cerebral metastases with HER2-targeting agents, but also the own effect of HER2+ tumor cells that may have a marked brain tropism. In this context, the development of prevention strategies is highly relevant. After a brief description of the natural history of HER2+ breast cancer, three different prevention strategies are discussed in this article, including a secondary prevention strategy by systematic screening of brain metastases, and two primary prevention strategies with prophylactic cerebral irradiation and the optimisation of the adjuvant treatment. None of these strategies has been validated to date. A prolonged follow-up is crucial in order to detail the natural history of HER2+ breast cancers and to evaluate the impact of new treatments on the incidence of brain metastases.