Targeted or reduced doses of radiotherapy after surgery can significantly reduce side effects for women with breast cancer, a clinical trial has shown. Changing clinical practice The Phase III IMPORT LOW trial – led by researchers at the Institute of Cancer Research, London (ICR), The Royal Marsden and the University of Cambridge – is changing clinical practice after finding that modified radiotherapy regimes were as effective as higher doses to the whole breast. During the trial, women received intensity-modulated radiotherapy (IMRT) – a technique pioneered by the ICR and The Royal Marsden, which shapes radiotherapy to the tumour. Compared with directing a high dose of radiation to the whole breast, targeting IMRT to part of the breast reduced the incidence of side effects by 23 per cent. The trial showed that some patients are more likely than others to experience side effects, including younger women, women with larger breasts, or women who were feeling anxious before beginning treatment. Women at higher risk could be offered extra support, monitoring or alternative treatment options, helping doctors to personalise patient therapy. The study was published in the Journal of Clinical Oncology and funded by Cancer Research UK.