1. Adenocarcinoma of the rectum classified clinically T2, T3a, T3b (penetration in the mesorectal fat between 1 to 5 mm) by TNM classification (Tumour Node Metastase), < 5 cm largest diameter, < half rectal circumference (by MRI staging), N0-N1 (any node < 8 mm diameter on MRI), M0