At the present time intra-operative radiotherapy is an experimental treatment for women with breast cancer. So it's availability is mainly restricted to clinical trials, which are testing how best it can be used.

Most women having surgery to remove breast cancer have a course of radiotherapy afterwards. This involves out-patient treatment, for four to six weeks - a total of 20 to 30 treatments all together.

Intra-operative radiotherapy is given differently. During breast surgery, while the woman is still under the anaesthetic, a probe is placed in the cavity left by the tumour. This is attached to a machine which delivers radiotherapy to the normal breast tissue around the edges of the cavity. The treatment lasts about half an hour and once it is over the operation continues as normal.

Intra-operative radiotherapy is not given to women who are having a mastectomy. It is only suitable for those having breast conserving surgery.

Early studies have been done to test its safety and a clinical trial is underway comparing the treatment with normal radiotherapy, to see whether it is as good.

The treatment requires specialised equipment and at the present time this is only available in one centre in the UK.

Normal radiotherapy treatment is very effective. If the clinical trial shows that intra-operative radiotherapy is as effective, the main benefit will be its convenience. Women won't need to attend so many radiotherapy treatments following surgery. It's less likely to give better results in terms of preventing the cancer coming back.