GM1 Prophylaxis for WBRT Related Cognitive Dysfunction

Inclusion Criteria: * Age between 18-75,with histological affirmative breast cancer ,and over 4 brain metastases ,need for WBRT suggested by radiotherapy oncologist ; * Estimated survival time over 6months; * Abundant hematological function:Absolute Neutrophil Count≥2×109/L ;platelet count≥100×109/L and hemoglobulin≥9 g/dL; * Abundant liver function：total bilrubin≤ULN；ASTandALT≤2.5ULN；AKP≤5ULN * Can cope with HVLT-RDR and ADAS-Cog evaluation * No prior therapy could induce neurological damage,within 4 weeks * No more that 1 degree peripheral neuropathy or any other diseases or symptoms that could hinder the evaluation of neurological AE * No more treatment or nursing is allowed after enrolling this trail * Written Informed Consent signed Exclusion Criteria: * PS score over 2,and estimated no attenuation by WBRT * Women with pregnancy or breast feeding * Unwilling to contraception measurement * Abnormal baseline impairment of cognitive impairment * Allergy to experiment agents or components * Unsuitable to GM1 treatment, evaluated by investigators * Active infection * RT dose over 30Gy