Abstract
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 discussed.
Highlights
Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related death in adult women worldwide
Six molecular subtypes of TNBC have been reported according to their gene ontologies and differential gene expression in specific genes involved in cell cycle, DNA damage response genes, androgen receptors, epidermal growth factor receptor, and signalling pathways, among others
In the present review, we focus only on those physiologically relevant in vitro and in vivo studies conducted with dietary phenolics that could elucidate whether they are responsible for the effects attributed to plant-based foods
Summary
Cancer is one of the world’s most substantial health problems and the second leading cause of death globally, with 9.6 million cancer-related deaths in 2018 [1,2]. Four clinical studies, conducted in women undergoing aesthetic breast, have allowed us to establish the identity and quantity of the isoflavone metabolites that can occur in human breast tissues after the intake of soy-based foods Overall, these studies showed that unconjugated daidzein, genistein, and the daidzein microbial-derived metabolite, equol, reached concentrations in the low nanomolar range, reporting higher levels for equol (in those equol-producer individuals) and daidzein than genistein [52,53]. The same authors tried to overcome one of the main limitations of these human studies, i.e., the long pre-surgery fasting that could hamper: (i) the detection of other phenolic-derived metabolites (including different metabolic forms), (ii) the occurrence of higher concentrations that could be reached in the breast tissues without fasting period.
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