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Case study: IMPORT LOW trial

The trial showed that partial breast radiotherapy is as effective as whole breast radiotherapy and caused fewer side effects.

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IMPORT LOW: Improving radiotherapy treatment for low risk early stage breast cancer

Key features

  • Recruitment open May 2007 – October 2010.
  • 2,018 women were recruited through 72 centres across 13 Local Clinical Research Networks.
  • Managed and analysed by the Institute of Cancer Research Clinical Trials and Statistics Unit, a Cancer Research UK funded Clinical Trials Unit, under Director Prof Judith Bliss.
  • The research team will continue to follow-up with participants and will look at the results again after ten years following randomisation.
  • Chief Investigator: Dr Charlotte Coles, Cancer Research UK Cambridge Centre, University of Cambridge (formerly Prof John Yarnold).
  • The trial showed that partial breast radiotherapy is as effective as whole breast radiotherapy and caused fewer side effects.

Surgery is often the first treatment for breast cancer. Research has shown that having whole breast radiotherapy after breast conserving surgery reduces the risk of the cancer coming back (relapse). However, breast cancer patients may experience long term side effects from whole breast radiotherapy. For example, their breasts may become harder or smaller.

Currently, patients have full dose radiotherapy to the whole breast after surgery even if they are considered at relatively low risk of their cancer coming back. In this large group of women, doctors set out to test the benefits of radiotherapy restricted to where cancer used to be (‘partial breast radiotherapy’), or a full dose restricted to where the cancer used to be and low dose radiotherapy to the rest of the breast (‘reduced dose radiotherapy’).

The aim of the IMPORT LOW trial was to compare these two approaches to standard whole breast radiotherapy in a group of women with early breast cancer who were at a low risk of relapse. The trial compared the following three treatments:

  • Standard dose of radiotherapy delivered to the whole breast in 15 doses over three weeks (standard treatment).
  • Standard dose radiotherapy to the area of the breast where the cancer used to be (partial breast radiotherapy).
  • Standard dose just to the area where the cancer used to be and low dose radiotherapy to the rest of the breast (reduced dose radiotherapy).

The trial tested whether reducing the extent and intensity of breast radiotherapy maintained the treatment’s effectiveness while reducing side effects, including change in breast appearance.

Outcomes and findings

The women who participated in the trial have continued to record their experiences of breast radiotherapy, which was given in three different ways. Five years on, the research team published results that confirm the effectiveness and safety of partial breast radiotherapy:

  • After an average of around 72 months, reduced dose radiotherapy and partial radiotherapy were as effective as whole breast radiotherapy at preventing local cancer relapse.
  • The overall survival and cancer-free survival time for all the women were similar in each of the three groups.
  • Longer term side effects were uncommon in all of the three groups, with severe long term effects of the treatment 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.

“After having a discussion with a research nurse and reading the trial information, I decided to take part because I felt it was very important to find out whether partial radiotherapy was just as effective for patients as it would have fewer side-effects. I hoped that I might benefit myself from taking part, but realised that even if I had the standard treatment I would still be very proud to contribute to the results.”

Hilary Stobart, IMPORT LOW trial participant

Value to the NHS

The IMPORT LOW trial showed that giving partial breast radiotherapy is simple, safe and effective for women with a low risk of their breast cancer returning.

  • Less toxicity may mean that fewer patients seek help with side effects.
  • For the majority of patients with cancer in the left breast (of whom the majority have tumours in the upper half of the breast, above the heart), it minimised the dose of radiotherapy the heart received without requiring patients to hold their breath during treatment. This made treatment easier for some patients, and treatment time shorter – meaning more patients can be treated during the working day.
  • Facilitated the development of 3D intensity modulated radiotherapy, a more accurate way of giving radiotherapy, throughout the UK (30 UK radiotherapy centres participated, many of which were using 2D breast radiotherapy routinely at the start of the trial).
  • Changed surgical practice. The British Association of Surgical Oncologists introduced a best practice recommendation in the wake of this trial to insert surgical clips around the tumour bed for all patients undergoing breast conserving surgery in order to optimise radiotherapy.
  • Formed part of the UK Royal College of Radiologists Breast Radiotherapy Consensus Guidance.

There is no extra training or resources required by sites so the treatment is easily implementable without any additional costs or resources.

There is the potential for further research to be undertaken to look at the possible effects of this treatment on developing a second cancer or heart problems a long time after treatment.

Key publications: