Population-based cohort study of molecular expression assay for prediction of recurrence after breast conserving surgery for ductal carcinoma in situ

Ductal carcinoma in situ (DCIS) is routinely treated with breast conserving surgery (BCS) followed by radiotherapy (RT). The inability to accurately estimate an individual’s risk of local recurrence (LR) and invasive LR using clinicopathologic factors (CPF) contributes to overtreatment of DCIS. A population-based cohort study at the University of Toronto (Canada) investigated the impact of incorporating the 12-gene DCIS score (DS) and the 21-gene Recurrence Score (RS) on the accuracy of predicting LR and invasive LR. The study showed that models including the DS or RS performed better in predicting the 10-year risk of LR compared with models based on CPD alone with excellent calibration. The two molecular-based models also performed better in predicting invasive LR compared with the CPF model. The model incorporating the RS did not perform better in the prediction of invasive LR compared with the DS-based model.