Dietary Phenolics against Breast Cancer. A Critical Evidence-Based Review and Future Perspectives

© 2020 by the authors.Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related death in adult women worldwide. Over 85% of BC cases are non-hereditary, caused by modifiable extrinsic factors related to lifestyle, including dietary habits, which play a crucial role in cancer prevention. Although many epidemiological and observational studies have inversely correlated the fruit and vegetable consumption with the BC incidence, the involvement of their phenolic content in this correlation remains contradictory. During decades, wrong approaches that did not consider the bioavailability, metabolism, and breast tissue distribution of dietary phenolics persist behind the large currently existing gap between preclinical and clinical research. In the present review, we provide comprehensive preclinical and clinical evidence according to physiologically relevant in vitro and in vivo studies. Some dietary phenolics such as resveratrol (RSV), quercetin, isoflavones, epigallocatechin gallate (EGCG), lignans, and curcumin are gaining attention for their chemopreventive properties in preclinical research. However, the clinical evidence of dietary phenolics as BC chemopreventive compounds is still inconclusive. Therefore, the only way to validate promising preclinical results is to conduct clinical trials in BC patients. In this regard, future perspectives on dietary phenolics and BC research are also critically discussedThis research was funded by the projects PID2019-103914RB-I00 (MICINN, Spain), 19900/GERM/15 (Fundación Séneca de la Región de Murcia, Spain), and 201870E014 and 201770E081 (CSIC, Spain). J.A.G.B. was supported by a Juan de la Cierva contract (IJCI-2016-27633) from the Ministry of Science, Innovation and Universities (Spain) and a Standard European Marie Curie Fellowship from the European Commission. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 838991.Peer reviewe