B1: If the tumour is < 3 cm, a CXB boost dose (90Gy/3 fractions/4 weeks) will be initially delivered to the tumour. After 2 weeks rest, patients will receive 3D conformal EBRT 45 Gy (1.8 Gy/fraction/5 weeks) with concurrent chemotherapy using capecitabine (825 mg/m2 bid, on radiation days). Clinical evaluation will be performed 3 weeks after the end of irradiation (week 14) and will guide the final strategy (surgery or W-W) as in arm A.