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

4. Nutritional Supplements

In cancer topic, three different phases could be passive of intervention with nutritional supplements: prevention, during conventional treatments after diagnosis and survival period.

Although studies have not established a specific role for vitamins and selenium in the prevention of breast cancer, some anticancer activities have been demonstrated using tumour cell lines (i.e., in vitro) [374–376].

Some notable institutions in cancer research, such as the American Cancer Society, the World Cancer Research Fund, and American Institute for Cancer Research, advise against the use of nutritional supplements for cancer survivors [377, 378]. Nevertheless, the supplementation with multivitamins and minerals is frequent after a breast cancer diagnosis and in survivors who recognize them as anticancer and antioxidant agents [26, 34, 113, 379]. Despite this, the evidence base for nutritional supplementation in cancer patients during treatment remains inconsistent and ambiguous and the results obtained in some studies have been contradictory. For example, some observational studies performed in breast patients have not reported improvements in breast cancer prognostic [152, 380]; others showed beneficial effects [112, 123, 381] and some showed harmful events [123].

The information obtained with the studies that examine the association between supplementation use and cancer-related outcomes must be interpreted with care due to the methodological limitations of most study designs such as lack of complete prospective data on supplement uses, specifically around the time of prediagnosis, diagnosis, and treatment and lack of data collection on changes in supplement use over time. Greenlee et al. [379] published a prospective cohort study (the Pathways study) with methodological improvements over previous studies in which the authors provided specific detailed information on changes in supplementation use following diagnosis in a multiethnic population. In this study, most women used vitamin/mineral supplements before (84%) and after (82%) diagnosis. The most commonly initiated supplements were calcium and vitamin D; the most commonly discontinued supplements were multivitamins, vitamin C and vitamin E. In another study, the Intergroup Phase III Breast Cancer Chemotherapy trial (S0221), the authors collected data between 2003 and 2010 and reported that 48% of patients were taking multivitamins; 20% were taking vitamins C and D and omega 3 fatty acids in fish oils; 15% were taking vitamins E and B6 and folic acid; and 34% were taking calcium. In this study, the advice of clinicians related to the nutritional supplementation was diverse [382]. This review refers only to the most commonly used nutritional supplements among the breast cancer patients.

After reviewing the available scientific literature [157], at this moment no consensual recommendation for cancer patients is available even among the clinicians and a greater understanding of processes involved in the regulation of tumour growth is desirable.