Incidence, risk factors and prognostic characteristics of bone metastases and skeletal-related events (SREs) in breast cancer patients: A systematic review of the real world data

Purpose The aim was to systematically extrapolate the occurrence, risk factors, prognostic characteristics, management and outcome of bone metastases (BM) and skeletal related events (SREs) of breast cancer survivors in the real world clinical setting. Methods A systematic literature search of PubMed, Web of Science, EMBASE OvidSP and EBSCO Academic Search Complete was conducted. Published prospective and retrospective papers investigating BM and SREs in breast cancer patients in non-trial settings were identified and systematically reviewed. Results Twenty-four studies met the inclusion criteria. Incidences of BM based on new diagnosis, length of BM-free interval (BMFI) and number and sites of BM were detected by 17 of 24 studies. Seven studies included in the review were subjected to analyses of risk factors for BM. Developments of SREs regarding the occurrence ratio of total and specific SREs, SERs-free interval (SREFI) and the first-line therapy for SREs were observed in 16 of 24 studies. Out of 5 studies, we extracted uni- and multivariate analysis of risk factor for SREs and out of 16 studies - predictors for survival in breast cancer patients with BM. Conclusions BM and SREs are common problems in non-trial breast cancer populations. Patient demographics, clinical stage, tumor pathological type, molecular receptors status are significantly risk factors for incidence of BM, SREs and the survival. The unique characteristics of BM and SREs in breast cancer patients should be taken into account in future randomized controlled trials, as to optimize individual treatment options and assure a maximally long good quality of life.