Short-course Radiotherapy (5×6Gy/7Gy/8Gy) Followed by Neo-adjuvant Chemotherapy for Locally Advanced Rectal Cancer

Patients will be enrolled into Group 1 to 3 according to the time order of entering the study to receive dose from 6Gy×5F to 8Gy×5F using the traditional 3+3 dose escalation design.