Endocrine therapy for breast cancer prevention has been shown to reduce risk, and for treatment of early stage oestrogen receptor-positive (ER-positive) breast cancer to reduce breast cancer mortality. The objective of the review is to synthesise available evidence on whether mammographic density reduction in these settings is (i) a prognostic biomarker and (ii) a predictive biomarker, as defined in the Introduction. We will explore sources of heterogeneity to identify the impact of differences in participants, measures of mammographic density, follow-up length and study design. Within the prognostic and predictive biomarker reviews, our analysis will consider prevention and treatment populations separately, and within these, selective oestrogen receptor modulators (SERMs) and aromatase inhibitors (AIs) separately.
This is a protocol.