http://informahealthcare.com/ijf ISSN: 0963-7486 (print), 1465-3478 (electronic) Int J Food Sci Nutr, Early Online: 1–42 ! 2014 Informa UK Ltd. DOI: 10.3109/09637486.2014.950207 REVIEW ARTICLE Diet and breast cancer: a systematic review Niki Mourouti, Meropi D. Kontogianni, Christos Papavagelis, and Demosthenes B. Panagiotakos School of Health Science and Education, Department of Nutrition and Dietetics, Harokopio University of Athens, Athens, Greece Abstract Breast cancer occurs as a result between genes–diet interactions. Concerning diet, only alcohol is widely recognized for being most consistently associated with breast cancer risk. The purpose of this review is to report through a systematic way the current scientific evidence relating breast cancer and diet, through original-research studies published in English language during the last decade, assessing the consumption of specific foodstuffs/ food-nutrients in relation to the disease. The available literature suggests that soy food intake seems to be inversely associated with the disease, while no association seems to be reported for dietary carbohydrates and dietary fiber intake. The consumption of dietary fat, is probably suggestive of an increase in breast cancer risk, while studies evaluating the role of fruit/ vegetable, meat as well as dietary patterns and breast cancer risk, provide inconsistent results. Diet seems to be modestly associated with the disease, highlighting the need for more studies to be conducted. Keywords Fiber, fruits and vegetables, meat, soy-food History Received 15 March 2014 Revised 18 July 2014 Accepted 21 July 2014 Published online 3 September 2014 Introduction Breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in females, worldwide, accounting for 23% (i.e. 1.38 million) of the total new cancer cases and 14% (458 400) of the total cancer deaths in 2008. About half the breast cancer cases and 60% of the deaths are estimated to occur in economically developing countries (Jemal et al., 2011). Well-established, non-dietary risk factors for breast cancer include hormone replacement therapy and exposure to ionizing radiation especially during puberty and adolescence. The risk is also increased by several reproductive and other factors that are not easily modified including: age (65+ versus 5 65 years, although risk increases across all ages until age 80), family history of breast cancer, early menarche ( 5 12 years), late menopause ( 4 55 years), late age at first full-term pregnancy and lack of breastfeeding. Moreover, there is consistent evidence that obesity and weight gain during adulthood are associated with an increased risk of breast cancer among post-menopausal (but not pre- menopausal) women (ACS, 2011–2012; WCRF/AICR, 2007). With respect to diet and breast cancer risk, during the last decades, studies from all over the world have evaluated the relationship between specific foods and some substances they contain with the development of breast cancer (Michels et al., 2007; Romieu, 2011; Thomson, 2012). Among them, only alcohol intake is widely recognized as one of the behaviors most consistently associated with breast cancer risk (WCRF/AICR, 2007). Moreover, the analysis of dietary patterns, an approach that has gained much of interest in modern nutrition epidemiology, instead of the study of specific foods and nutrients, has sparsely been reported in the literature regarding breast cancer development. The aim of this work was to review and evaluate the current scientific evidence about the relationship between specific foodstuffs (i.e. alcohol, fruits, vegetables, meat, soy food and soy intake) that have been extensively studied in the literature the past years, and breast cancer risk. Selection of studies The PRISMA guidelines for reporting systematic reviews were followed here (Moher et al., 2009). In particular, original- research studies that were published in English language during the past decade, between 1 January 2002 and 31 August 2012, were selected through a computer-assisted literature search (i.e. Medline via Pubmed and Scopus). Computer searcher used combinations of key words relating to breast cancer (i.e. breast cancer or breast neoplasm), foodstuffs (i.e. alcohol, fruits, vegetables, meat, soy food and soy intake) or food substances/ nutrients they contain (i.e. heterocyclic compounds, amines, dietary fiber, dietary carbohydrate, glycemic index, dietary fat and fatty acids). In addition, the reference lists of the retrieved articles directed the search to relevant present articles that were not allocated through the searching procedure. Only studies published in English have been considered. We have included cohorts and case–control studies, meta-analyses and clinical trials. We excluded studies referring to dietary habits of women during adolescence and to consumption of supplements. The endpoint was only breast cancer incidence and not recurrence or survival. At this point, it should be mentioned that reading carefully the existing literature, and based on the great diversity among studies regarding the way they have evaluated exposure dietary factors Correspondence: Prof Demosthenes B. Panagiotakos, 46 Paleon Polemiston St., 16674, Glyfada, Greece. Tel: +30 210 9603116. Fax: +30 210 9600719. E-mail: d.b.panagiotakos@usa.net Int J Food Sci Nutr Downloaded from informahealthcare.com by University of Connecticut on 10/11/14 For personal use only.