Aspects cliniques : Cancers HER2 et atteinte du système nerveux central, que faire en 2021 ?

Metastatic breast cancer is the second most common cause of brain metastasis (BM), and this problem is particularly marked for the amplified HER2 subtype (HER2+), with a cumulative incidence reaching up to 49 % in the ER–/HER2+ subgroup. Literature review shows that therapeutic progress has been major since the marketing of systemic anti-HER2+ treatments, with life expectancies now relatively unaffected by brain development. The recommended treatments are, on the one hand, specific treatment for brain development and, on the other hand, appropriate systemic treatment. Regarding local treatments, we will always favor surgery when possible, especially for large metastases, and stereotaxic radiotherapy, possibly iterative. One should bewary of whole brain irradiation which has never been shown to improve overall survival, but which is clearly associated with more cognitive toxicities. All the systemic anti-HER2 treatments currently on the market have shown efficacy on BM from HER2+ breast cancer and must therefore be chosen above all on the basis of their potential activity on the systemic disease at the time of cerebral evolution. If BM evolution happen without concomitant systemic progression, and local treatment can control it, it is not recommended to change the current medical treatment. Finally, randomized clinical studies opened to patients with active brain disease are starting to be published. The first of them showed the benefit of the triple combination tucatinib-trastuzumab-capecitabine in this context.