Dr Vrieling talks to ecancertv at ECC 2015 about a substudy of the 1,616-patient EORTC 'boost no-boost' trial, focusing on the impact of pathological factors on long-term local control in women with early breast cancer undergoing radiotherapy after breast conserving surgery, some of whom who were given an additional dose of radiotherapy.

Young age, high-grade invasive disease and ductal carcinoma in situ (DCIS) were factors increasing the local recurrence rate. However, in patients with all three of these negative prognostic factors, giving the additional boost of radiation reduced the local relapse risk by almost 80% (hazard ratio of 0.21).

These long-term results show the important and ongoing negative influence of additional DCIS on local control, Dr Vrieling says. The radiation boost continued to have a positive effect on local control after adjusting for systemic therapy, even after 5 years.