Phytotherapy and Nutritional Supplements on Breast Cancer 用于乳腺癌治疗的植物疗法和营养补充剂

3.1. Echinacea

Echinacea, a member of the family Asteraceae, has a long history of medicinal use. It is endemic to eastern and central North America and is also cultivated in Europe. Three different species of Echinacea can be used as phytotherapeutic products: Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida [3].

Some authors justified the potential use of Echinacea as an anticancer agent based on its rich content in flavonoids that act as an immune-stimulant by promoting the activity of lymphocytes thus increasing phagocytosis and the activity of natural killer cells and inducing interferon production [35].

Although studies indicated the use of Echinacea among breast cancer patients [30, 33, 34], there are not many studies, even in vitro, that demonstrated its effects in this type of cancer. Driggins et al. verified that despiteEchinacea pallida decreasing the growth rate of BT-549 mammalian breast cancer cells, its effect was significantly lower as compared to Echinacea purpurea [36]. Huntimer and collaborators used Echinacea angustifolia roots and evaluated their activity when combined with doxorubicin (i.e., cytotoxic agent) in MCF-7 human breast cancer cell line [37]. This study showed that different constituents of Echinacea could have a different effect on MCF-7 cell proliferation and could interfere with cells treated with anticancer drug, affecting cell proliferation despite the presence of doxorubicin (i.e., counteracting the cell-killing activity of doxorubicin). Based on this effect, the authors suggest that herbal medicines need to be examined more closely for interactions with other chemotherapeutic agents. Echinacea induce cytochrome P450 3A4 isoenzyme system both in vitro and in humans [38, 39]. This enzyme system participates in the metabolism of many chemotherapeutic agents. Goey et al. demonstrated that the recommended dose and schedule of a commercially available Echinacea purpurea extract (A. Vogel Echinaforce®, Biohorma BV, Elburg, Netherlands) did not interact with docetaxel pharmacokinetics and this combination can be used safely [40]. Among other therapeutic indications, docetaxel is approved for the treatment of locally advanced or metastatic breast cancer. The benefits of the use of Echinacea to reduce unwanted effects of radiotherapy (e.g., leukopenia) are unclear [41]. Therefore, more clinical evidence is important to support or refute the recommendations for Echinacea in relation to cancer management.

Even though Echinacea seems to be relatively safe, it may cause liver damage or suppress the immune system if used for a prolonged period without a break (i.e., more than 8 weeks) [42]. Therefore, a patient with liver disturbance or taking drugs that potentially cause liver toxicity (e.g., some chemotherapy agents) should avoidEchinacea use.