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Low-fat dietary pattern and breast cancer mortality by metabolic syndrome components: a secondary analysis of the Women's Health Initiative (WHI) randomised trial

Pan K, Aragaki AK, Neuhouser ML, Simon MS, Luo J, Caan B, Snetselaar L, Mortimer JE et al.

British journal of cancer, 2021

48,835 participants · 19 citations

Abstract

Background: In the Women's Health Initiative (WHI) dietary modification (DM) randomised trial, the low-fat dietary intervention reduced deaths from breast cancer (P = 0.02). Extending these findings, secondary analysis examined dietary intervention influence on breast cancer mortality by metabolic syndrome (MS) components.

Methods: In total, 48,835 postmenopausal women with no prior breast cancer were randomised to a low-fat dietary intervention or comparison groups. Four MS components were determined at entry in 45,833 participants: (1) high waist circumference, (2) high blood pressure, (3) high cholesterol and (4) diabetes history. Forest plots of hazard ratios (HRs) were generated with P-values for interaction between randomisation groups and MS component score. Primary outcome was death from breast cancer by metabolic syndrome score.

Results: HRs and 95% confidence intervals (CI) for dietary intervention influence on death from breast cancer were with no MS components (n = 10,639), HR 1.09, 95% CI 0.63-1.87; with 1-2 MS components (n = 30,948), HR 0.80, 95% CI 0.62-1.02; with 3-4 MS components (n = 4,246), HR 0.31, 95% CI 0.14-0.69 (interaction P = 0.01).

Conclusions: While postmenopausal women with 3-4 MS components were at higher risk of death from breast cancer, those randomised to a low-fat dietary intervention more likely had reduction in this risk.

Registry: ClinicalTrials.gov (NCT00000611).

How strong is the evidence?

Evidence Hub reads this as a secondary / pooled analysis, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 48,835 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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