In research to be presented to the 2013 European Cancer Congress (ECC2013), Professor John Yarnold will say that, until now, there has been contradictory evidence as to whether gaps between radiotherapy treatments, for instance overnight or at weekends, makes any difference to the overall effectiveness of radiotherapy on breast cancer, and, if it does make a difference, why that could be. "Traditionally, breast cancer has not been regarded as a fast growing cancer, unlike some other cancer types, but our research now suggests that a significant part of the daily radiotherapy curative dose is ‘used up’ in compensating for tumour growth overnight and over weekends. We have estimated that the amount of radiotherapy dose that is used up in this way corresponds to approximately 0.60 Gray (Gy) per day," says Prof Yarnold, who is Professor of Clinical Oncology at The Institute of Cancer Research, London, and Honorary Consultant at the Royal Marsden NHS Foundation Trust (London, UK). "This is the first numerical estimate to suggest that the duration of a course of radiotherapy has an effect on local cancer cure for patients with early breast cancer…