Rituximab-Methotrexate-Temozolomide-Thiotepa (RMTT) Regimen As First-line Therapy for PCNS DLBCL

Rituximab: 375 mg/m2 intravenously on day 3,7; Methotrexate: 1.5-3.5 g/m2 intravenously on day 1,14(≤65 ,3.5g/m2；\>65,1.5g/m2); Temozolomide 150 mg/m2 on days 3-7； Thiotepa:40 mg/m2 intravenously on day 17。 Treatment will be given for 4 cycles（28 days for each cycle）, and patients who achieve a CR or better can choose to undergo ASCT or WBRT(23.4Gy).