Prof John Yarnold talks to ecancertv at the UK's National Cancer Research Institute ( NCRI ) 2013 meeting about optimial radiotherapy for breast cancer.

Breast cancer is as sensitive to radiation fraction size as normal tissues, 10-year follow-up of clinical trials, including the UK START trials, has shown.

This means it makes sense to give early breast tumours fewer, larger doses of radiation, rather than more, smaller doses.

The result has been to switch from a standard five-week schedule of 25 fractions to a more convenient three-week schedule delivering 15 fractions of 2.7 Gy.

Current 15-fraction schedules are standard of care for local-regional radiotherapy in the UK, but 15- or 16-fraction regimens are unlikely to represent the lower limit.

It is now important to find out if there is wide variation between breast cancers in their sensitivity to different levels of radiation.

If there is a lot of variation between cancers, it highlights the need to identify tests to exploit this variation for the benefit of future patients.
By the end of this decade, research could bring about a regimen of local-regional radiotherapy with as few as five fractions for women with early breast cancer.

John Yarnold is Professor of Clinical Oncology at The Institute of Cancer Research, London, and Honorary Consultant at the Royal Marsden NHS Foundation Trust.