Circulating tumor cells (CTCs) have the potential to provide a surrogate for'real-time biopsy' of tumor biological activity. Enumeration and molecular characterization of CTCs in colorectal cancer could play an important role in diagnosis, predicting the risk for tumor recurrence, and providing novel target therapy biomarkers. In view of these facts, the investigators wanted to demonstrate the value of multiparameter flow cytometry in detecting human tumor cells of colorectal cancer in normal peripheral blood after cryosurgery with or without dendritic cell(DC)-cytokine-induced killers(CIK) treatment, and the investigators also compared the specificity with reverse transcriptase polymerase chain reaction (RT-PCR) method.

1 day before and 2 days after cryosurgery with or without DC-CIK treatment，approximately 17-mL ethylene diamine tetraacetic acid(EDTA)-blood was drawn by vein puncture from patients with colorectal cancer and healthy volunteers. The blood of the healthy volunteers will be used to evaluate the sensitivity and specificity and as negative control cells. To avoid contamination with skin cells, 2 mL blood will be discarded before the study samples will be taken.Briefly, the mononucleate cells will be separated from the blood over Ficoll- Paque for 20 min with 1800g at 4℃. The interface cells will be removed and washed, and the red blood cells(RBCs) will be removed using a lysis buffer followed by a repeated wash. The mononuclear cells will be counted and aliquot for RT-PCR and multiparameter flow cytometry on the basis of at least 2-3×106 cells for each methodology. The cell pellet will be resuspended in phosphate-buffered saline for multiparameter flow cytometry and in Trizol reagent for RT-PCR. Aim : Identification of CTCs may lead to better diagnosis and prognosis and could help to choose an adequate therapy.

Inclusion Criteria:

1. Age:18-75
2. Karnofsky performance status >60
3. Diagnosis of colorectal cancer based on histology or the current accepted radiological measures.
4. Classification tumor,nodes,metastasis-classification(TNM) stage: Ⅱ,Ⅲ,Ⅳ
5. Will receive cryosurgery and/or DC-CIK treatment
6. Life expectancy: Greater than 3 months
7. Patients' routine blood test, liver function and kidney function have no obvious abnormalities
8. Ability to understand the study protocol and a willingness to sign a written informed consent document

Exclusion Criteria:

1. Patients with other primary tumor except colorectal cancer
2. History of coagulation disorders or anemia

Patients with Ⅱ,Ⅲ,Ⅳ stage colorectal cancer come to Fuda Hospital for treatment.