Adulthood dietary and lifestyle patterns and risk of breast cancer: Global Cancer Update Programme (CUP Global) systematic literature review

Abstract

Background: An increasing number of studies in recent years investigate various dietary and lifestyle patterns and associated breast cancer (BC) risk.

Objectives: This study aimed to comprehensively synthesize and grade the evidence on dietary and lifestyle patterns and BC risk.

Methods: Databases were systematically searched up to 31 March, 2022, for evidence from randomised controlled trials and prospective cohort studies on adherence to a dietary pattern alone or in combination with lifestyle behaviors and incidence of or mortality from primary BC in adult females. Findings in all, premenopausal, and postmenopausal females were descriptively synthesized instead of meta-analyzed due to patterns heterogeneity. An independent Global Cancer Update Programme Expert Panel graded the strength of the evidence.

Results: A total of 84 publications were included. Results for patterns reflecting both a healthy diet and lifestyle were more consistent than for patterns that included diet only. There was strong-probable evidence that a priori World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) and American Cancer Society (ACS) dietary and lifestyle scores may reduce BC risk in all and postmenopausal females, whereas in premenopausal females, less evidence was found contributing to limited-suggestive grade. There was also a limited-suggestive evidence that adherence to the Healthy Lifestyle Index and other diet and lifestyle scores may reduce BC risk in postmenopausal females; a posteriori Western/Meat/Alcohol dietary patterns may increase BC risk in postmenopausal females; and Prudent/Vegetarian/Mediterranean dietary patterns may reduce BC risk in all females. For the remaining patterns, evidence was graded as limited-no conclusions.

Conclusions: Advice to adopt combined aspects of a healthy diet and lifestyle according to WCRF/AICR and ACS scores, encouraging a healthy weight, physical activity, alcohol and smoking avoidance, and a healthy diet rich in fruits, vegetables, (whole)grains and cereals and discouraging red and processed meat, can be proposed to females to lower BC risk. This review was registered at PROSPERO as ID CRD42021270129 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021270129) on 28 August, 2021, and further updated on 4 May, 2022, in order to extend the search period.

Keywords: a posteriori dietary patterns; a priori dietary patterns; breast cancer incidence; dietary and lifestyle patterns; evidence grading; hybrid dietary patterns; systematic review.

FIGURE 1

Flowchart representing each step of the screening process and inclusion of publications for this review.

FIGURE 2

Relative risks (RRs) and 95% CIs of breast cancer incidence for the highest compared with the lowest level of adherence to a priori dietary and lifestyle patterns: (A) based on cancer-specific recommendations; (B) based on general recommendations for a healthy lifestyle. For comparability between studies [to show the comparison between the highest (the best) with the lowest (the worst) level of adherence to the pattern] the estimates (95% CI) from the study by Akinyemiju et al. [25] were inverted (A); and those from the studies by McKenzie et al. [26] and Chen et al. [27] were recalculated using an approach implemented in Excel software and described by Hamling et al. [28] (B). Scores analyzed only continuously per 1-unit increment in the WCRF/AICR score: in all females, RR: 0.87; 95% CI: 0.74, 1.03 [29]; in premenopausal females, RR: 0.98; 95% CI: 0.81, 1.17 [30] and RR: 1.04; 95% CI: 0.95, 1.15 [31]; in postmenopausal females, RR: 0.83; 95% CI: 0.75, 0.92 [30] and RR: 0.94; 95% CI: 0.87, 1.02 [31]. AARP, formerly the American Association of Retired Persons) Diet and Health Study; ATP, Alberta’s Tomorrow Project; BWHS, Black Women’s Health Study; CNBSS, Canadian National Breast Screening Study; CSDLH, Canadian Study of Diet, Lifestyle and Health; CSECK, Cancer Screening Examination Cohort of Korea; E3N, Étude Épidémiologique auprés des femmes de la Mutuelle Générale de l’Éducation Nationale (MGEN); EPIC, The European Prospective Investigation into Cancer and Nutrition; IWHS, Iowa Women’s Health Study; NOWAC, Norwegian Women’s and Cancer Study; Q, quintile; SMC, Swedish Mammography Cohort; SUN, Seguimiento Universidad de Navarra Study; VITAL, Vitamins And Lifestyle Study; WHI-OS, Women’s Health Initiative Observational Study.

FIGURE 3

Relative risks (RRs) and 95% CIs of breast cancer risk for the highest compared with the lowest level of adherence to a priori dietary patterns: (A) Mediterranean dietary pattern; (B) provegetarian/plant-based dietary patterns; (C) Healthy Eating Index (HEI) and Alternate Healthy Eating Index (AHEI) scores. Results from the publication by Toledo et al., originally published in 2015 [32], present estimates (95% CI) recalculated accounting departures from the protocol of individual randomization [33]. Scores analyzed only continuously per 1-tertile increment in the Mediterranean dietary score in all women (RR: 0.98; 95% CI: 0.92, 1.05) [34]. CTS, California Teachers Study; EPIC, The European Prospective Investigation into Cancer and Nutrition; MEC, Multiethnic Cohort Study; METCA, The Prospective Meta-Cohort Study of Cancer Burden in Finland; NHS, Nurses’ Health Study; NLCS, The Netherlands Cohort Study; PREDIMED, PREvención con DIeta MEDiterránea Clinical Trial; Q, quartile; SCHS, Singapore Chinese Health Study; SUN, Seguimiento Universidad de Navarra Study; SWLH, The Swedish Women’s Lifestyle and Health Study; T, tertile; UKDCC, UK Dietary Cohort Consortium; UKWCS, UK Women Cohort Study.

FIGURE 4

Relative risks (RRs) and 95% CIs of breast cancer risk for the highest compared with the lowest level of adherence to a posteriori dietary patterns: (A) Western/Meat /Alcohol; (B) Prudent/Vegetarian/Mediterranean. ATP, Alberta’s Tomorrow Project; BCDDP, The Breast Cancer Detection Demonstration Project; BWHS, Black Women’s Health Study; CNBSS, Canadian National Breast Screening Study; CSDLH, Canadian Study of Diet, Lifestyle and Health; CTS, California Teachers Study; DIETSCAN, A common approach for analyzing dietary patterns; E3N, Étude Épidémiologique auprés des femmes de la Mutuelle Générale de l’Éducation Nationale (MGEN); EPIC, The European Prospective Investigation into Cancer and Nutrition; HEXA-G, Health Examinees-Gem Study; JACC, Japan Collaborative Cohort Study; JPHC, Japan Public Health Center–based Prospective Study; MCCS, Melbourne Collaborative Cohort Study; NHS, Nurses’ Health Study; NLCS, The Netherlands Cohort Study; ORDET, Hormones and Diet in Etiology of Tumors Study; Q, quartile; SCHS, Singapore Chinese Health Study; SMC, Swedish Mammography Cohort; SUN, Seguimiento Universidad de Navarra Study; T, tertile.