Flavonoids in Triple Negative Breast Cancer: Chemopreventive Phytonutrients

Flavonoids are phytochemicals that found in a variety of fruits and vegetables and known to possess anti-oxidant, antiinflammatory and anti-cancer properties [1,2]. It has been considered that flavonoids rich diet intake has promising role in human cancer prevention including breast cancer [3]. These phytonutrients have been traditionally used in Chinese and Ayurvedic medicine and are found to be associated with lower risk of breast cancer [4,5]. According to epidemiological studies, breast cancer is the most common malignancies in women around the globe [6]. Breast cancer has heterogeneous nature with each of its subtype shown distinct morphological and clinical behavior [7]. Several factors including genetic, epigenetic and transcriptomic alterations are proved to be responsible for this diverse nature of breast cancer [8]. Among other subtypes triple negative breast cancer (TNBC) is highly aggressive form of breast cancer [9]. Statically TNBC alone comprises of 10%-17% of all breast carcinomas with incidence rate of 6%-28% of breast cancer [10]. Although, TNBC accounts for small proportion of all breast cancers, but has high mortality rate due to its aggressive nature. TNBC is characterized by the absence of estrogen receptors (ERs), progesterone receptors (PRs) and human epidermal growth factor receptor 2 (HER2) with normal breast tissue–like, and basal-like phenotype [10]. Lack of ERs, PRs and HER2 in TNBC makes it more difficult to treat [11]. Currently used hormonal or targeted therapies are only effective against those tumors that has either overexpressed receptors or transcriptional factors. Since neither receptors nor HER2 overexpression is occurred in TNBC therefore the therapies are found to be ineffective [11]. Interestingly, several in-vitro experiments determined the risk reducing effect of flavonoids in TNBC and suggesting them as a promising therapy.