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

1. Introduction

Breast cancer is a significant public health problem in both developed and developing countries [1, 2]. Despite superior diagnostic skills and valuable advances in its treatment during the last decades, breast cancer persists in representing one of the most commonly diagnosed occurring cancers and leading cause of cancer deaths among women worldwide [3]. According to World Health Organization (WHO) it is estimated that worldwide over 508,000 women died in 2011 due to breast cancer [4]. The epidemiologic parameters (e.g., incidence, mortality, and survival rates) related to breast cancer diverge significantly between countries and regions [1, 5] which could be attributed to various factors such as health habits, lifestyle changes (e.g., dietary changes), exposure to radiation, family history, related alterations in menstrual cycle patterns, early detection, and access to the current knowledge concerning breast cancer [3, 5].

The stage of diagnosis influences both the prognostic and the treatment strategies for breast cancer. Currently, standard treatment protocol combines a multidisciplinary approach involving different therapies such as surgery, radiation, and medical oncology (i.e., chemotherapy, immunotherapy, and hormonal therapy) to obtain a local (i.e., remove or destroy cancer in the breast) or systemic (i.e., destroy or control cancer cells throughout the body) effect [3].

Despite the high incidence, breast cancer survivors, which used Complementary and Alternative Medicines (CAM), associated with standard cancer therapy, namely, chemotherapy and radiotherapy, are increasing [6, 7]. The use of CAM is growing among the public, up to 65% of the European population uses this modality of medicine, and it is commonly practiced among cancer patients [8]. Some studies associated the increased CAM use with sociodemographic issues such as female gender, higher levels of education, higher income, and health insurance [9–12] that explains its advance in many developed countries.

CAM is defined as a group of different modalities, including diverse medical and healthcare systems, products, and practices, which are not usually considered part of standard medical treatments [13]. This type of medicine could be used together with and thereby complement conventional medicine which is referred to as complementary medicine (e.g., using acupuncture to assist the side effects of conventional cancer treatment) or in place of conventional medicine (e.g., using a special diet to treat cancer instead of a conventional cancer treatment) [13, 14]. Despite alternative medicine being based on functional hypotheses often conflicting with conventional medicine, the complementary one uses the scientific approach of evidence-based medicine to support the conventional medicine. Currently an additional and promising term is emerging in this area, the “integrative medicine” which is based on the integration of conventional and complementary approaches together in a coordinated way that have been confirmed to be safe and effective [13, 15]. In CAM perspective, the patients are evaluated as a whole with all their complexities and connections instead of focusing on isolated pathological processes [15].

There are different classifications of CAM therapies which vary mainly with time and institutional approaches. In accordance with the National Centre for Complementary and Integrative Health, a reference USA Federal Agency, CAM therapies can be divided into three broad categories [13]:(i)Natural products which include dietary supplements (e.g., vitamins, minerals, and probiotics) and phytotherapeutic products.(ii)Mind and body practices and manipulations which include different procedures or techniques such as yoga, chiropractic and osteopathic manipulation, meditation, massage therapy, acupuncture, relaxation techniques, tai chi, healing touch, qi gong, hypnotherapy, and movement therapies.(iii)Other complementary health approaches which include some approaches that may not neatly fit into either of the previous group, for example, traditional healers, Ayurvedic Medicine, Traditional Chinese Medicine, Homeopathy, and Naturopathy.

In the oncology field, the patient survival rates have increased in recent years, so the practice of integrative care, termed integrative oncology [16] (Figure 1), makes the acceptance of the holistic approach to cancer care by medical professionals feasible, once CAM modalities can meet various needs of the patients that go beyond the simple alleviation of severe side effects of conventional cancer treatments. This fact explains the use of CAM approaches by a great proportion of cancer patients [17, 18] and, among these patients, women with breast cancer remain the most likely users of some form of CAM modalities [12, 19–21] with an estimated rate as high as 75% [22]. Dobos et al. reported the practice of the concept of integrative oncology for breast cancer patients by German cancer centres such as the Department of Internal and Integrative Medicine, Kliniken Essen-Mitte, academic teaching hospital of the University of Duisburg-Essen, and the Breast Centre at Kliniken Essen-Mitte [16].

The reasons reported by breast cancer patients for the widespread use of CAM diverge and include [12, 19] activating the immune system, curing cancer, alleviating symptoms associated with the side effects of conventional cancer treatments, enhancing quality of life, increasing the perception of disease control, and preventing relapse and prolonging survival. Consequentially, the patients attempt to be active and gain autonomy [23].

However, the use of certain CAM methods in oncologic processes (i.e., a life-threatening disease) may become problematic and several partly substantial risks for the health of patient can arise, particularly when, as commonly happening, patients use them arbitrarily and do not report this information to their oncologists [19, 24–26]. This is true mainly for CAM recommendations or treatments that interfere/interact with chemotherapy or endocrine/hormonal treatment approaches, such as phytotherapeutic products and dietary supplements, or have intrinsic toxicity or other negative effects. Despite such interactions possibly being beneficial, in some situations, the concomitant use of CAM and conventional medicines approaches could compromise or be in conflict and enhance the drug toxicity or reduce the effectiveness [27]. A well-known example is phytoestrogens that might neutralize endocrine therapies. So, there are some CAM modalities that require a temporary adjustment of their use during periods of conventional treatment [28]. Additionally, among the CAM modalities, the consumer of these natural products is the most popular in breast cancer patients [19, 24] probably due to the assumption that “natural” products are less toxic than conventional prescribed medicines [29]. Therefore, attending the proactive role that nowadays the patients have in relation to their health, it is crucial to have reports in integrative medicine to guide and support clinicians and patients. The aim is to improve clinical/healthcare outcomes in combining CAM and conventional care and prevent misuse of CAM methods and preparations. The purpose is also to prevent harmful interactions and to enrich personal control over disease.

Based on the intensive investigation of nutritional supplements and phytochemicals as breast cancer therapeutics, the aim of this study is to compile and to explore the available scientific information regarding the most common phytotherapeutic and nutritional supplement products used in breast cancer patients. Therefore, recent scientific evidence studies (e.g., systemic reviews and clinical investigation studies) are consulted and the clinical relevant and validated outcomes concerning efficacy, safety, and limitations of the clinical data are reported.

2. Methodology