Aprepitant Without Steroid in Preventing Chemotherapy-induced Nausea and Vomiting in Patients With Colorectal Cancer

Inclusion Criteria:

* Diagnosis of colorectal cancer
* No prior chemotherapy and scheduled to receive FOLFOX chemotherapy (oxaliplatin,leucovorin and 5-fluorouracil)
* Age ≥18 years
* Eastern Cooperative Oncology Group (ECOG) Performance Status 0, 1 or 2
* Laboratory index: Hemoglobin ≥ 90 g/L (No blood transfusion within 14 days), Absolute Neutrophil Count ≥ 1.5×10\^9/L, Platelet Count ≥ 75×10\^9/L, Serum Bilirubin ≤ 1.5×ULN, ALT and AST ≤ 3.0×ULN (without liver metastases), ALT and AST ≤ 5.0×ULN (with liver metastases), Serum Creatinine ≤ 1×ULN, Endogenous Creatinine Clearance\>60ml/min
* Be able to read, understand and complete the questionnaire and diary
* Be able to understand the study procedures and sign informed consent.

Exclusion Criteria:

* Treatment with any other study medicine within 4 weeks before enrollment.
* Nausea or vomiting ≤ 24 hours prior to registration
* Ongoing emesis due to obstruction of digestive tract
* Concurrent use of olanzapine, phenothiazine or amifostine
* Female with pregnancy or lactation
* Severe cognitive compromise
* Known history of CNS disease (e.g. brain metastases, seizure disorder)
* Concurrent abdominal radiotherapy
* Chronic alcoholism
* Known hypersensitivity to aprepitant, tropisetron, or dexamethasone.
* Known cardiac arrhythmia, uncontrolled congestive heart failure or acute myocardial infarction within the previous six months.
* History of uncontrolled diabetes mellitus
* Serious or uncontroled infection
* Known active HIV, viral hepatitis or tuberculosis infections