Total Neoadjuvant Therapy Followed by 'Watch and Wait' Approach or Organ Preservation for Low-risk Rectal Cancer

Aim: To investigate the safety and efficacy of organ preservation (OP) with watch-and-wait strategy (W\&W) or local excision (LE) in MRI stratified low-risk rectal cancer treated by total neoadjuvant treatment. Meanwhile we will look into the role of ctDNA in the prediction of regrowth and metastasis in the wait and wait process. Methods: Low-risk rectal cancer with following MRI features are recruited: mid-low tumor, mrT2-3b, MRF(-), EMVI(-), differentiation grade 1-3. Patients will receive IMRT 50.6Gy/22f with concurrent capecitabine and 4 cycles of consolidation CAPEOX. Patients with cCR/near-cCR were recommended for 'watch \& wait' approach or local excision (LE). The OPR and sphincter preservation rate (SPR) at 2 years will be analyzed. As the extension of PKUCH-R01, BJCC-R01 trial will upgrade to a multi-center research enrolled 3 other colorectal center in Beijing.