Impact of homologous recombination deficiency biomarkers on outcomes in patients with early breast cancer: a systematic review protocol

INTRODUCTION: Patients with breast cancer with homologous recombination deficiency (HRD) such as germline BRCA1/2 mutations would respond to DNA-damaging drugs. Several clinical studies have revealed that HRD biomarkers were associated with the outcomes of patients with early breast cancer (EBC). However, no systematic review has determined the prognostic role of HRD biomarkers in patients with EBC. Therefore, this study will systematically combine and analyse the results of previous studies, to facilitate the clinical use of HRD detection in EBC. METHODS AND ANALYSIS: We will search five databases including PubMed, Cochrane Library, EMBASE, OVID and Web of Science through December 2021, with no language restriction. Two reviewers will independently screen all records based on pre-established inclusion and exclusion criteria. The main outcomes include pathological complete response, disease-free survival and Ooerall survival. In addition, all studies included must contain the detection of HRD score, HRD status or HRD-related gene mutational status and protein expression. Data extraction will be carried out by two reviewers independently according to a self-designed template. The Newcastle-Ottawa Quality Assessment Scale and Jadad Scale will be used for quality assessment for cohort studies and randomised clinical trials, respectively. Review Manager V.5.3.5 will be used to perform meta-analysis. Both the Q test and I(2) statistic will be used to assess heterogeneity. Subgroup and sensitivity analyses will be conducted if significant heterogeneity appears and cannot be reduced by using a random-effect model. ETHICS AND DISSEMINATION: Ethical approval is not required for a systematic review. The results will be disseminated through international and national conferences or peer-reviewed publications. PROSPERO REGISTRATION NUMBER: CRD42021286522.