A randomised phase III study of radiation doses and fractionation schedules in non-low risk DCIS of the breast

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Treatment of ductal carcinoma in-situ (DCIS), a preinvasive form of breast cancer, is aimed at preventing invasive cancer recurrence. Women with higher-risk DCIS have an increased risk of recurrence. This study aims to individualise treatment for women with DCIS to achieve long-term tumour control with minimal treatment toxicity. After local excision of DCIS, radiotherapy (RT) to the whole breast reduces the recurrence rate. However, it is unclear if escalating radiation dose to the tumour bed in higher-risk women increases tumour control. It is also uncertain if giving fewer but larger radiation doses over 3-4 weeks would achieve the same tumour control as the standard 5-7 week course of RT to improve patient convenience and access to RT. Thus, this multicentre study of 610 women with higher-risk DCIS will investigate if adding a tumour bed radiation boost after whole breast RT improves tumour control, and the shorter RT course achieves the same tumour control as the standard longer course. Currently, the ability to predict the malignant potential of DCIS and RT toxicity is limited. This study will investigate if there are biological and genetic markers predictive of invasive recurrence and normal tissue toxicity in women with DCIS using state of the art technology. Women need to weigh up the likelihood of cancer control against adverse treatment effects to make an informed treatment decision. However, very little is known about the quality of life (QoL) consequences of the diagnosis and treatment of DCIS. In this study, the QoL, psychological distress, perceived risk of invasive cancer recurrence and perceived cosmetic outcomes of women with DCIS, will be assessed using a questionnaire of validated measures. This study will refine treatment for women with DCIS according to their risks of recurrence. It will significantly advance the understanding of the biology of DCIS and its psychological and QoL outcomes after treatment.