The goal of this clinical trial is to test the safety and efficacy of local excision (LE) or non-operative management (NOM) in patients with MRI defined low-risk rectal cancer following neoadjuvant intensity modulated radiotherapy with concurrent capecitabine plus consolidation CapeOX. The main questions it aims to answer are:

1. What is the organ-preservation rate (OPR) after in patients with MRI defined low-risk rectal cancer following neoadjuvant intensity modulated radiotherapy with concurrent capecitabine plus consolidation CapeOX?
2. Is LE or NOM safe and effective in patients with MRI defined low-risk rectal cancer following neoadjuvant intensity modulated radiotherapy with concurrent capecitabine plus consolidation CapeOX? Participants will receive radical surgery, LE, or NOM based on the response of neoadjuvant intensity modulated radiotherapy with concurrent capecitabine plus consolidation CapeOX in patients with MRI defined low-risk rectal cancer.

Inclusion Criteria:

• Age ≥ 18 years and ≤85 years
• ECOG Performance status 0-1
• Histologically confirmed diagnosis of adenocarcinoma of the rectum, with tumor differentiation Grade 1-3
• The distance from down verge of tumor to anal-rectal junction (ARJ) ≤4cm based on MRI, or ≤8 cm based on sigmoidoscopy
• Clinical Stage T2 or T3a or T3b and EMVI (-) and MRF (-) and extra-mesorectal metastatic lymph node (-) based on MRI
• The maximum diameter of the tumor is ≤4cm or the circumferential invasion range is less than 1/3 of the intestinal circumference
• No evidence of distant metastases
• No prior pelvic radiation therapy
• No prior chemotherapy or surgery for rectal cancer
• No active infections requiring systemic antibiotic treatment
• ANC > 1.5 cells/mm3, HGB > 10.0 g/dL, PLT > 100,000/mm3, total bilirubin ≤ 1.5 x ULN, AST≤ 3 x ULN, ALT ≤ 4 x ULN
• Patients must read, agree to, and sign a statement of Informed Consent prior to participation in this study.

Exclusion Criteria:

• Recurrent rectal cancer
• Primary unresectable rectal cancer. A tumor is considered unresectable when invading adjacent organs and an en-bloc resection will not achieve negative margins
• Creatinine level greater than 1.5 times the upper limit of normal
• Patients who have received prior pelvic radiotherapy
• Patients who are unable to undergo an MRI
• Patients with a history of a prior malignancy within the past 5 years, except for well treated basal cell cancer, squamous cell skin cancer, breast cancer, thyroid cancer or small renal cancer, and with DFS >5 years
• Patients with a history of any arterial thrombotic event within the past 6 months. This includes angina (stable or unstable), MI, TIA, or CVA
• Other anticancer or experimental therapy
• Women who are pregnant or breast-feeding
• Patients with any other concurrent medical or psychiatric condition or disease which would make them inappropriate candidates for entry into this study.