MammaPrint® gene expression profile in deciding adjuvant chemotherapy for early breast cancer

Abstract

ABSTRACT : Introduction The vast majority of breast cancers are diagnosed in early stages, where adjuvant chemotherapy would be warranted only among patients in ‘high risk’ of distant relapse. Besides classical pathological features, several gene expression tools, such as MammaPrint® (MMP) verified in MINDACT trial, serve to include chemotherapy in a tailored treatment plan. Purpose Our main objective was to check if MMP is fruitful in clinical practice, by identifying a population in whom adjuvant chemotherapy can be safely avoided.Methodology 152 women tested from January, 2014 to May, 2018 were included in a retrospective study. We analyzed: 1) Distribution of clinical pathological and conventional molecular features through ‘low’ and ‘high risk’ MMP subgroups. 2) Disease free survival (DFS) of ‘low risk’ estimated patients, thus treated without chemotherapy. Results and discussion As classical features are distributed unfairly among both genomic groups, none of them is able to rule out adjuvant chemotherapy. By contrast, MammaPrint® allows us to avoid 66% of chemotherapy prescription. In fact, DFS of free-chemotherapy patients was 99% at 22 months of median follow-up. Conclusions MammaPrint® is a reproducible tool in clinical practice, able to identify patients where an aggressive therapy should not be recommended.