It is quite likely that although your treatment is two weeks longer than your friend's you are both receiving the same amount of radiotherapy.

There are a number of different schedules for giving radiotherapy for early breast cancer. Some take three weeks while others can take up to six or seven weeks.

Despite the difference in the length of time taken for treatment it's thought that the effects of the different schedules are very similar.

The effects of radiotherapy don't only depend on the length of the course of treatment. The dose of radiation given is also important. Often shorter courses of treatment give a slightly higher dose of radiotherapy in each session (or fraction). So, the total dose of radiation given over the whole course is very similar, whether you have the short course or the long.

This probably sounds confusing - and it is. It would be far simpler if there were just one or two radiotherapy treatment schedules which were used for all patients with early breast cancer. Research trials that have compared three weeks of radiotherapy to five, have found very similar results.

A trial in the UK called the START trial (the initials stand for STAndardisation of breast RadioTherapy) hope to answer this question. However the results will not be available until 2007.