The study is designed to analyze the pathological tumor response on locally advanced rectal cancer after preoperative treatment with neo-adjuvant therapy regimen or with chemotherapy combined with short-course radiotherapy in a prospective cohort and to correlate this response with patient's outcome

This is a phase II , open label, randomized study in patients with confirmed diagnosis of locally advanced rectal cancer. The study is designed to analyze the pathological tumor response on locally advanced rectal cancer after preoperative treatment with neo-adjuvant therapy regimen or with chemotherapy combined with short-course radiotherapy.

Inclusion Criteria:

• 1. Consent to this study
• 2. Histological or cytological confirmed diagnostic of rectal carcinoma
• 3. Locally advanced rectal cancer without metastasis, confirmed by pelvic MRI (cT3CRM+、cT4NX or cTxN2M0)(cT3CRM+: margin between the deepest point of tumor and rectal adventitia/serosa surface is less than 1 mm measured in pelvic MRI)
• 4.With no presence of anemia (Hb≤60g/l) induced by tumor bleeding or bowel obstruction
• 5.With no presence of other organ metastasis or extra-regional lymph node involvement
• 6.With no history of chemotherapy
• 7.ECOG score is 0 or 1
• 8.Adequate ability of bone marrow, liver and kidney function
• 9.No pregnancy

Exclusion Criteria:

1. Unable to intake oral medicine
2. Arrhythmia need treatment(besides β-blocker or digoxin); Symptomatic coronary artery disease or history of myocardiac infarction within 6 months ；Congestive Heart Failure NYHA II grade or severe
3. HIV infection or Active chronic HBV or HCV
4. Severe clinical infection at active stage
5. Epileptic seizure need treatment
6. History of organ transplantation
7. Renal failure or intaking renal dialysis
8. Clinical hemorrhagic tendency or Disorders of blood coagulation or intaking anticoagulant or thrombolytics
9. Severe unhealed wound or skin ulcer or bone fraction
10. Measurable massive ascites 11 History of other malignant tumor(except cured cervical tumor in site and cured cutaneous basal cell carcinoma) in last 5 years

12.Chronic inflammatory bowel disease， bowel obstruction，hereditary fructose intolerance 13.Medicine abuse；medical，psychologic or social conditions might disturb patients or results 14.Known or suspected allergy to any drugs in this study 15.Any situation or status that might endanger patient's safety or compliance 16.Pregnant woman or suckling period woman; Fertility without taking sufficient contraception 17.History of pelvic radiotherapy