External Beam Re-irradiation in Rectal Cancer.

Locally recurrent rectal cancer results in significant symptoms and is associated with prognosis of less than 1 year unless radical resection can be offered. Unfortunately, radical resection rates are low and therefore strategies to palliate symptoms and to maximise downstaging are of significant interest. As the majority of those presenting with locally recurrent rectal cancer will have received previous irradiation for their primary tumour, re-irradiation may offer benefit in this setting. The literature to date is considered in both palliative patients and those with potentially operable disease. Palliative patients gain significant symptomatic relief from standard dose fractionations of up to 30 Gy. In potentially operable patients, the evidence is discussed in the context of key questions; including indications for treatment, dose and fractionation, radiotherapy technique, margins and constraints. Finally, we highlight some additional areas of interest for consideration in future research and development.