Association Between Dietary Total Fat Intake and Risk of Breast Cancer: A Meta-Analysis of Case-Control and Cohort Studies.

Authors

Mehdi Karimi, Malihe Jafari, Eshagh Sedighi, Maryam Sharifi, Kimia Kazemi, Omid Asbaghi

Published in

Health science reports. Volume 9. Issue 6. Pages e72017. Epub Jun 23, 2026.

Abstract

Breast cancer represents the most prevalent malignant neoplasm and remains a principal cause of mortality among women worldwide. Despite extensive investigation, the association between dietary fat intake and breast cancer risk has yet to be definitively established. Consequently, this study aimed to conduct a systematic review and meta-analysis of existing case-control and cohort studies to elucidate the relationship between overall dietary fat consumption and breast cancer risk.
A systematic search was conducted across online databases up to May 2025 to identify relevant case-control and cohort studies. The meta-analysis employed a random-effects model to pool multivariable-adjusted effect sizes (ESs), evaluating heterogeneity using the I² statistic and assessing publication bias.
The meta-analysis of 75 ESs from case-control studies indicated that women with the highest total dietary fat intake had a significantly increased risk of breast cancer compared to those with the lowest intake (ES: 1.23; 95% CI: [1.12, 1.34]; p < 0.001; I² = 67%), suggesting a 23% higher risk. In contrast, the pooled analysis of 59 ESs from cohort studies showed no statistically significant association between total dietary fat intake and breast cancer risk (ES: 1.03; 95% CI: [0.99, 1.06]; p = 0.112; I² = 45%).
Case-control studies demonstrate a significant association between total dietary fat intake and breast cancer risk, whereas cohort studies do not report a statistically significant relationship. This disparity suggests a possible short-term effect of dietary fat on breast cancer risk, while evidence regarding its long-term impact remains inconclusive and warrants further investigation.

PMID:
42344423
Bibliographic data and abstract were imported from PubMed on 25 Jun 2026.

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