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

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) and given in daily doses, called fractions. 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)