Prospective Evaluation Of High-Dose Systemic Methotrexate In Patients With Breast Cancer And Leptomeningeal Metastasis

Inclusion Criteria * Adults (male and female) age \>18 * Eastern Cooperative Group (ECOG) Performance Scale 0-1 (see Appendix I) * Histologically or cytologically confirmed invasive breast cancer of the following subtype: * TRIPLE NEGATIVE (ER-negative, PR-negative, and HER2-negative disease). Triple-negative patients will be defined per ASCO-CAP Guidelines. * HER2-POSITIVE: HER2-positive patients will be defined per ASCO-CAP Guidelines. * HORMONE REFRACTORY: Patients with ER/PR-positive disease according to ASCO-CAP guidelines above may be considered if they have disease progression after two lines of hormonal therapy (administered in the adjuvant or metastatic setting), or are deemed clinically hormone-resistant taking into consideration the rate of progression of disease or a short interval of time on first line hormonal therapy before progression. Clinically hormone-resistant patients MUST also be discussed with the Study Chair, Study co-chair or designee in advance for approval. NOTE: ASCO-CAP guidelines state that ER and PR assays be considered positive if there are at least 1% positive tumor nuclei in the sample on testing in the presence of expected reactivity of internal (normal epithelial elements) and external controls. HER2-positive is defined as HER2 IHC 3+, ISH ≥ 2.0, or average HER2 copy number ≥ 6.0 signals. NOTE: A patient who has a change in receptor status (e.g. PR negative to positive) may be stratified as triple negative or hormone positive, contrary t…