The purpose of this study is to evaluate the value of dynamic change in detecting CTCs in peripheral blood from stage III rectal cancer patients undergoing neoadjuvant Folfox treatment and chemoradiotherapy,before and after surgery.

Circulating tumor cells (CTCs) have the potential to provide a surrogate for'real-time biopsy' of tumor biological activity. Enumeration of CTCs in rectal cancer patients could play an important role in diagnosis, predicting the risk for tumor recurrence and effectiveness of neoadjuvant therapy.

The investigators choose several timepoints to detect the dynamic change of CTCs,1 day before the 1st ,3rd and 5th(if the patient needs before surgery) neoadjuvant therapy course,1 day before and 7days ,3 month,6 month after surgery. Approximately 7.5-mL ethylene diamine tetraacetic acid(EDTA)-blood was drawn by vein puncture from patients with rectal cancer . Briefly, the number of CTCs will be count by the cellsearch system , recorded and analysed by the investigator.

Inclusion Criteria:

1. Age: >18 years old.
2. Diagnosis of stage III rectal cancer based on histology.
3. Will receive neoadjuvant treatment using Folfox or chemoradiotherapy .
4. Life expectancy: Greater than 3 months.
5. Patients have no severe inflammation, such as vasculitis.
6. 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 rectal cancer.
2. History of coagulation disorders or anemia.

not ready to share the data