Safety and efficacy of olanzapine for the prevention of chemotherapy-induced nausea and vomiting in colorectal cancer patients

Interventions: Drug : Experimental group takes olanzapine 5mg po a day for 3days. Control group takes placebo 5mg po a day for 3days. Primary outcome(s): Check the patient experience nausea or vomitting Primary Purpose : Treatment, Intervention Model : Parallel, Blinding/Masking : Double, Blinding Target : Subject, Investigator, Allocation : RCT