Radiotherapy is often given for anal cancers and advanced rectal cancers.
Radiotherapy for anal cancer, is given instead of surgery (primary radiotherapy) with surgery indicated only if there is an incomplete response to radiotherapy or a relapse.
Radiotherapy for advanced rectal cancer is often given in addition to surgery. This is preferably given before surgery (neo-adjuvant radiotherapy). Rarely, is radiotherapy given after surgery (adjuvant radiotherapy).
Pre-operative (neo-adjuvant) radiotherapy for rectal cancer can be given as a short course over 5 days, or for larger tumours it can be given as long course over 6 weeks.