A trial comparing different ways of giving radiotherapy for low risk early stage breast cancer (IMPORT LOW)

The trial team found that partial breast radiotherapy or reduced dose radiotherapy worked as well as the standard radiotherapy treatment.

They also found that the long term side effects were the same, or less, with the partial breast or reduced dose radiotherapy compared with standard whole breast radiotherapy.

2,018 women took part in this phase 3 trial. Two women did not want to be included in the trial results.

Everyone was put into one of 3 treatment groups at random by a computer. Both the women and their doctors knew which treatment group they were in.

Group 1 – whole breast radiotherapy
674 women were put into this group. Of these, 666 women had standard radiotherapy to the whole breast. 8 women did not have the allocated radiotherapy. This was for a number of reasons, including the women choosing not to have this treatment. Or that the radiotherapy was no longer a suitable treatment for them.

Group 2 – reduced dose radiotherapy
673 women were put into this group. Of these, 648 women had reduced dose radiotherapy to the whole breast, with standard dose radiotherapy to the area where the cancer had been. 25 women did not have the allocated radiotherapy.

Group 3 – partial breast radiotherapy
669 women were in this group. Of these, 641 had standard dose radiotherapy only to the area where the cancer had been, with no radiotherapy to the rest of the breast. 28 did not have the allocated radiotherapy.

The trial team looked at how often the cancer came back in the area where the cancer had been. This is called local relapse. After an average of around 72 months the number of women with local relapse was:

• 9 in group 1
• 3 in group 2
• 6 in group 3

The trial team concluded that reduced dose radiotherapy and partial radiotherapy were as effective as whole breast radiotherapy at preventing local relapse.

The trial team also looked at:

• the amount of time people lived overall – this is called overall survival
• the amount of time people lived without any signs of their cancer – this is called disease free survival
• recurrence of cancer in areas other than where the cancer had been before

They concluded that these were similar in each of the 3 groups after 5 years.

116 of the 2016 women died during the trial. 26 of them died from breast cancer.

Side effects
After 5 years, the trial team looked at the side effects of radiotherapy treatment on the breast. They looked at a combination of:

• before and after radiotherapy treatment photographs
• questionnaire feedback from women taking part
• physical examinations

Longer term side effects were uncommon in all of the 3 groups. And severe long term effects of the treatment were very rare.

Women reported having fewer changes to their breast appearance in the partial breast radiotherapy than those having standard treatment.

Fewer women reported having breast hardness in the reduced and partial radiotherapy groups than those having standard treatment.

The trial team think that this way of giving partial breast radiotherapy is safe and effective for women with a low risk of their breast cancer coming back. They suggest that doctors could give this type of radiotherapy easily to women in most treatment centres worldwide.

The trial team are interested in comparing this study with other trials looking at partial breast radiotherapy. And they suggest more research looking at the possible effects of this treatment on developing a second cancer or heart problems a long time after treatment.

The trial team will continue to follow up as many women taking part in IMPORT LOW as possible. They will look at the results again after 10 years.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.