Association between whole grain intake and breast cancer risk: a systematic review and meta-analysis of observational studies - PubMed (original) (raw)

Meta-Analysis

doi: 10.1186/s12937-018-0394-2.

Yuebin Ke 1, Shuang Wu 1, Suli Huang 1, Siguo Li 1, Ziquan Lv 1, Eng-Kiong Yeoh 2, Xiangqian Lao 2, Samuel Wong 2, Jean Hee Kim 2, Graham A Colditz 3, Rulla M Tamimi 4 5, Xuefen Su 6

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Meta-Analysis

Association between whole grain intake and breast cancer risk: a systematic review and meta-analysis of observational studies

Yunjun Xiao et al. Nutr J. 2018.

Abstract

Background: Epidemiological studies have found that high whole grain intake may be associated with a reduced risk of breast cancer. However, the evidence has not been consistent. We conducted a meta-analysis to quantitatively assess the association between whole grain intake and breast cancer risk.

Methods: Relevant observational studies were identified by searching PubMed, Embase, Cochrane library databases, and Google Scholar through April 2017. Summary relative risk (RR) estimates were calculated using random-effects meta-analysis.

Results: A total of 11 studies, including 4 cohort and 7 case-control studies and involving 131,151 participants and 11,589 breast cancer cases, were included in the current meta-analysis. The pooled RR of breast cancer for those with high versus low whole grain intake was 0.84 (95% confidence interval [CI]: 0.74 to 0.96, p = 0.009; I2 = 63.8%, p for heterogeneity = 0.002). Subgroup analysis by study design found a significant inverse association in the case-control studies (RR: 0.69; 95% CI: 0.56 to 0.87, p = 0.001; I2 = 58.2%, p for heterogeneity = 0.026), but not in the cohort studies (RR, 0.96; 95% CI: 0.82 to 1.14, p = 0.69; I2 = 66.7%, p for heterogeneity = 0.029). In addition, stratified analysis suggested that sample size could be a potential source of heterogeneity.

Conclusions: Results of the current meta-analysis suggest that high intake of whole grains might be inversely associated with a reduced risk of breast cancer, and the inverse association was only observed in case-control but not cohort studies. More large-scale cohort studies are needed to confirm the inverse association observed.

Keywords: Breast cancer; Meta-analysis; Observational studies; Whole grain.

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The authors declare that they have no competing interests.

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Figures

Fig. 1

Fig. 1

Flow chart of study selection. Flow chart shows literature search for whole grain intake in relation to risk of breast cancer

Fig. 2

Fig. 2

Forest plot shows the association between highest category of whole grain intake and the risk of breast cancer. CH, cohort study, CC, case-control study

Fig. 3

Fig. 3

Forest plot shows the association between high and intermediate levels of whole grain intake and the risk of breast cancer

Fig. 4

Fig. 4

Forest plot shows the association between whole grain intake (per 50 g/day) as a continuous variable and the risk of breast cancer

Fig. 5

Fig. 5

Meta regression analysis of the association between the dose of whole grain intake and the risk of breast cancer

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