RT Journal Article T1 Long-term complete response to intrathecal trastuzumab in a patient with leptomeningeal carcinomatosis due to her2- overexpressing breast cancer: Case report. A1 García, Francisco José Valdivia A1 Carrión, Natalia Palazón A1 de la Cruz-Merino, Luis AB Leptomeningeal dissemination due to HER2-overexpressing breast cancer is a rare and hard to treat complication with short-term dismal prognosis. A 34-year-old female previously treated because of HER2+ breast cancer is admitted to the Neurology Department in December 2016 due to sensory-motor neurological semiology. A wide set of diagnostic tests is performed and finally cytologic findings after repeated CSF confirm leptomeningeal infiltration by breast carcinoma (panCK+, GATA3+). Weekly intrathecal triple therapy with methotrexate, cytarabine and hydrocortisone plus trastuzumab is carried out during 4 months. Clinical and pathological response that lasts more than 24 months. Leptomeningeal carcinomatosis is an oncological situation where conventional therapies have limited activity. In HER2+ advanced breast cancer patients, intrathecal therapy with anti-HER2 therapy (trastuzumab) is feasible and may reach long-term disease control, especially in cases of low-tumor burden. YR 2020 FD 2020 LK http://hdl.handle.net/10668/14910 UL http://hdl.handle.net/10668/14910 LA en DS RISalud RD Apr 6, 2025