- Locally invasive high-risk rectal adenocarcinoma as defined by the presence on MRI of at least one of the following: i) Tumours within 1mm of mesorectal fascia i.e. circumferential resection margin threatened or involved ii)T3 tumours at/below levators iii)Tumours extending ≥5mm into peri-rectal fat iv)T4 tumours (including the involvement of bladder or vagina if surgical resection is possible with clear margins) v)Presence of extra-mural venous invasion (primary tumour is therefore at least T3) vi)T2 N0/1/2 tumours requiring Abdomino-Perineal Excision, within 1mm of mesorectal fascia i.e. circumferential resection margin threatened or involved