This is a phase III randomized controlled trial comparing the efficacy and safety of FOLFOXIRI versus CapeOX as neoadjuvant regimen in treating patients with middle and upper locally advanced (MRI T3-4 or N+) rectal cancer. This study aims to optimize the neoadjuvant therapy for patients with anus-preserving resectable locally advanced rectal cancer, so as to improve the prognosis of them. It remains unclear about whether FOLFOXIRI or CapeOX neoadjuvant chemotherapy is more effective for locally advanced rectal cancer.

Inclusion Criteria:

• MRI evaluated of T3-4 or N+ rectal cancer;
• Pathologically diagnosed of rectal adenocarcinoma;
• 18 to 75 years old;
• Distance from lower margin of tumor to anus <15 cm and suitable for anus-preserving resection;
• Tumor amenable to radical resection;
• Treatment-na?ve patients with no previous systemic chemotherapy, radiotherapy or local excision for treating rectal cancer;
• Laboratory requirements conducted within 7 days of starting study treatment: Neutrophil count ≥ 1.5×10^9/L, Platelet count ≥ 100×10^9 /L, Hemoglobin ≥ 80 g/L, Serum bilirubin ≤ 24umol/L, Alanine aminotransferase and aspartate aminotransferase ≤ 60 U/L, Serum creatinine ≤ 110 umol/L;
• Be capable to receive a surgery;
• No second tumor at present or in the past 5 years, except skin basal cell carcinoma, skin squamous cell carcinoma, or any in situ cancer;
• No previous systemic chemotherapy for treating colorectal cancer;
• Life expectancy of more than 3 months;
• No current pregnancy or breast-feeding, and subjects at childbearing age shall take method of contraception;
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) ≤ 1;
• Be willing and able to understand the study and to provide written informed consent.

Exclusion Criteria:

• End-stage cachexia patients;
• Cardiopulmonary dysfunction or liver and kidney dysfunction, and unable to tolerate chemotherapy or surgery;
• Metastatic carcinoma;
• Incomplete or complete intestinal obstruction;
• Known to be allergic to capecitabine, 5-Fu, oxaliplatin or irinotecan;
• Pregnant or lactating women; or women who have fertility but have not taken at taken adequate contraceptive measures;
• Have vital organ failure or other severe diseases, including but not limited to coronary heart disease, cardiovascular diseases, or myocardial infarction within 12 months before being included; severe neurological or psychiatric historysevere infection; active disseminated intravascular coagulation; active hepatitis, severe coagulation disorder patients;
• History of other malignancy within the past 5 years except effectively treated skin basal cell carcinoma, skin squamous cell carcinoma, or any in situ cancer;
• Serious organic disease including but not limited to heart, kidney, brain, and lung.

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