Clinical Research Directory

Inclusion Criteria: * pathological confirmed adenocarcinoma * clinical stage T2-4 and/or N+, inappropriate for local excision * the distance from anal verge less than 5 cm, or considered inappropriate for anal preservation by surgeons. * Strong desire to preserve the anus, able to receive close surveillance for at least 2 years after chemoradiotherapy. * without distance metastases * aged between 18 to 75 years old. * performance status score: 0\~1 * UGT1A1\*28 6/6 or 6/7 * sign the inform consent Exclusion Criteria: * pregnancy or breast-feeding women * serious medical illness * difficult to achieve complete response assessed by current evidence: the maximal diameter of tumor \>10cm; the maximal diameter of lateral lymph node \>2cm; baseline CEA\>=100; biopsy pathology confirmed signet ring cell carcinoma components; digital rectal examination found that the tumor is peri-narrowed. * baseline blood and biochemical indicators do not meet the following criteria: neutrophils≥1.5×10\^9/L, Hb≥90g/L, PLT≥100×10\^9/L, ALT/AST ≤2.5 ULN, Cr≤ 1 ULN * DPD deficiency * UGT1A1\*28 7/7