A trial looking at different ways of giving radiotherapy for women with early breast cancer (FAST)

Cancer type:

Breast cancer




Phase 3

This trial compared standard radiotherapy for early breast cancer with 2 new radiotherapy schedules to see which was best at reducing the side effects from radiotherapy. This trial was supported by Cancer Research UK.

If you had breast conserving surgery for early breast cancer, you may also have had radiotherapy. Tests may have shown that there were no cancer cells in the margin of healthy tissue around your cancer, but some cancer cells could still have been left behind. The aim of radiotherapy was to destroy any cancer cells left at the site of the operation.

Radiotherapy is measured in units called ‘Grays’ (Gy) Open a glossary item and given in daily doses, called fractions Open a glossary item. At the time of this trial, the standard treatment for women having radiotherapy for breast cancer was to give a small fraction of radiotherapy every week day for 5 weeks. Small fractions of radiation had been thought to cause fewer side effects to the healthy normal tissues of the breast. But recent results of other clinical trials (involving over 7,000 women) suggest that larger fractions may be as effective at killing cancer cells although causing fewer side effects.

Researchers in this trial wanted to find out if increasing the dose of each fraction (and using fewer fractions) while decreasing the total dose, would reduce the side effects of radiotherapy. This was a randomised trial. The women taking part were put into 1 of 3 treatment groups. Neither they nor their doctor could choose which group they were in. The 3 groups were

  • 25 fractions of 2 Gray (total dose 50 Gray) – standard treatment
  • 5 fractions of 6 Gray (total dose 30 Gray)
  • 5 fractions of 5.7 Gray (total dose 28.5 Gray)

Summary of results

The trial team found that the side effects of giving 5 doses of 5.7 Gray (total 28.5 Gray) was about the same as giving 25 doses of 2 Gray (total 50 Gray) but significantly milder than 5 doses of 6 Gray (total 30 Gray).  

This trial recruited 915 women. Each woman was asked to have photographs taken of their breast

  • Before radiotherapy
  • 2 years after radiotherapy
  • 5 years after radiotherapy

The research team then looked for changes in the shape, size and overall appearance of the breast since radiotherapy and graded them as none, mild or marked. Of the 915 women in the trial, the researchers were able to look at the 2 year photos of 729 women.

For the 239 who had a total dose of 50 Gray

  • 189 had no change
  • 46 had a mild change
  • 4 had a marked change

For the 248 who had a total dose of 30 Gray

  • 160 had no change
  • 65 had a mild change
  • 23 had a marked change

For the 242 who had a total dose of 28.5 Gray

  • 184 had no change
  • 49 had a mild change
  • 9 had a marked change

After an average follow up of just over 3 years, 2 women had cancer that had come back in the same breast (local recurrence).

The research team concluded that, regarding side effects of radiotherapy to the breast, 5 doses with a total of 28.5 Gray was about the same as 25 doses with a total of 50 Gray but was significantly milder than 5 doses with a total of 30 Gray.   

Follow up is continuing in the trial and updated results will be published in the future.

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

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor J. Yarnold

Supported by

Cancer Research UK
Institute of Cancer Research (ICR)
National Institute for Health Research Cancer Research Network (NCRN)

Other information

This is Cancer Research UK trial number CRUKE/04/015.

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 478

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Harriet wanted to try new treatments

A picture of Harriet

“I was keen to go on a clinical trial. I wanted to try new cancer treatments and hopefully help future generations.”

Last reviewed:

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