Eligible patients will be randomized to receive different antiemetic regimens . In the experimental group,patients will receive aprepitant, palonosetron and dexamethasone .In the other group,patients will accept the same dose of palonosetron and dexamethasone. During the treatment, any grade of nausea and vomiting should be recorded in order to evaluate the complete response rate of CINV,nausea patients will be measured by a visual analogue scale (VAS) ,other adverse events should be recorded as well.