Prospectively Investigate the effectiveness and safety of neoadjuvant cetuximab + chemotherapy (mFOLFOX6) combined with short-course radiotherapy (25Gy/5Fx) for RAS wild-type locally advanced rectal cancer

Inclusion Criteria:

1. A biopsy proven histological diagnosis of rectal adenocarcinoma；

2. An ARMS-PCR proven KRAS, NRAS, PI3KCA and BRAF wild type;

3. No intestinal obstruction, distant metastasis was excluded by CT, MRI or PET / CT;

4. MRI proven T3c-T4, CRM positive, N2, extramural vascular invasion positive or lateral lymph node positive of locally advanced rectal cancer;

5. Age between 18-75 years;

6. ECOG (Eastern US Cooperative Oncology Group) score: 0-1;

7. Has sufficient organ function:

   • Hemopoietic function: hemoglobin ≥ 90 g / L, platelet ≥ 80 g / L × 109 / L, neutrophils ≥ 1.5 × 109/L
   • Liver function: ALT and AST < 2.5 × ULN;
   • Renal function: serum creatinine < 1.5 ULN;

8. Willing to participate and informed consent signed；

Exclusion Criteria:

1. Patients with mutations in any of KRAS, NRAS, or BRAF, microsatellite instablility-High;
2. Patients having undergone chemotherapy, radiotherapy or surgery for colorectal cancer;
3. Patients with other uncontrolled malignant tumors (except early-stage basal cell carcinoma or cervical carcinoma in situ) ;
4. Female patients who are pregnant or breastfeeding;
5. Patients with severe heart, liver, or kidney, or neurological or psychiatric disease;
6. Patients with active infection;
7. Poor overall health status, ECOG ≥ 2;
8. Patients with concomitant diseases that seriously endanger the safety of patients or affect the completion of the study in the judgment of the investigator;
9. Known hypersensitivity reactions to any investigational drugs;

Patients aged 18 to 75 years with locally advanced rectal cancer, regardless of gender, ethnicity and regional distribution, were involved in this study. Patients were required to be in good health and have sufficient organ function and bone marrow function.