Preoperative high dose rate brachytherapy for rectal cancer is safe but there is no evidence that this procedure gives additional benefit when used as a boost to another type of radiotherapy (external beam radiotherapy). And there is not much evidence about how well it works when used alone, without external beam radiotherapy. It should only be used if extra care is taken to explain the uncertainty about how well it works and extra steps are put in place to record and review what happens.
More research on this procedure is needed and NICE may look at it again if more evidence is published.
Your health professional should fully explain what is involved in having this procedure and discuss the possible benefits and risks with you. In particular, they should explain the uncertainty about the evidence on how likely it is to improve your symptoms. You should also be told how to find more information about the procedure. You should only be asked if you want this procedure after having this discussion. Your health professional should ask you if details of your procedure can be collected.