Radiation Doses and Fractionation Schedules in Non-low Risk Ductal Carcinoma In Situ (DCIS) of the Breast

Specific objectives: 1. To evaluate time to local recurrence in women with DCIS treated with breast conserving surgery followed by: * whole breast RT alone versus whole breast RT plus tumour bed boost; * RT using the standard fractionation schedule versus the shorter schedule. 2. To evaluate time to disease recurrence and overall survival in women with DCIS treated with breast conserving surgery followed by: * whole breast RT alone versus whole breast RT plus tumour bed boost; * RT using the standard fractionation schedule versus the shorter schedule. 3. To compare the toxicity of: * whole breast RT alone versus whole breast RT plus tumour bed boost; * RT using the standard fractionation schedule versus the shorter schedule. 4. To compare the cosmetic outcome of: * whole breast RT alone versus whole breast RT plus tumour bed boost; * RT using the standard fractionation schedule versus the shorter schedule. 5. To identify a molecular signature predictive of invasive recurrence of DCIS to facilitate therapy individualization. 6. To assess inter-relationship of biomarkers and relationship between biomarker expression and specific histopathologic features of DCIS. 7. To evaluate the quality of life of women treated with: * whole breast RT alone versus whole breast RT plus tumour bed boost; * RT using the standard fractionation schedule versus the shorter schedule.