Phytoestrogens for Cancer Prevention and Treatment

Simple Summary Phytoestrogens are compounds derived from plants that have a similar structure to human sex hormones. This has led to the observation that phytoestrogens have comparable effects to these hormones in our cells. Some beneficial effects of phytoestrogens include the improvement of menopausal symptoms and the prevention of several diseases. In fact, the consumption of soy and soy foods among the Asian population has been associated with a decrease in the incidence of some types of tumors. However, there are some concerns about whether these compounds may also have harmful effects, such as interfere with cancer treatments. In this review, we collect data on the reported effects of phytoestrogens alone or in combination with anti-cancer treatments and discuss the controversy around using these compounds. Phytoestrogens are a large group of natural compounds found in more than 300 plants. They have a close structural similarity to estrogens, which allow them to bind to both estrogen receptors (ER), ER alpha and ER beta, presenting a weak estrogenic activity. Phytoestrogens have been described as antioxidant, anti-inflammatory, anti-thrombotic, anti-allergic, and anti-tumoral agents. Their role in cancer prevention has been well documented, although their impact on treatment efficiency is controversial. Several reports suggest that phytoestrogens may interfere with the effect of anti-cancer drugs through the regulation of oxidative stress and other mechanisms. Furthermore, some phytoestrogens could exert a protective effect on healthy cells, thus reducing the secondary effects of cancer treatment. In this review, we have studied the recent research in this area to find evidence for the role of phytoestrogens in cancer prevention and therapy efficacy.