Association between dietary factors and breast cancer risk: a matched case-control study in Vietnam.

Background: The role of diet in breast cancer prevention is controversial and limited in low-middle-income countries (LMICs). This study aimed to investigate the association between different dietary factors and breast cancer risk in Vietnamese women.

Methods: Three hundred seventy newly histologically confirmed breast cancer cases and 370 controls matched by 5-year age from September 2019 to March 2020 in Ho Chi Minh City were recorded dietary intake using a validated food frequency questionnaire. Odds ratios (OR) and 95% confidence intervals (95% CI) were evaluated using conditional logistic regression and adjusted with potential confounders.

Results: Compared to the lowest quartile of intake, we found that the highest intake of vegetables, fruit, soybean products, coffee, and egg significantly decreased breast cancer risk, including dark green vegetables (OR 0.46, 95% CI 0.27-0.78, p=0.022), legumes (OR 0.19, 95% CI 0.08-0.44, p <0.001), starchy vegetables (OR 0.37, 95% CI 0.21-0.66, p=0.003), other vegetables (OR 0.46, 95% CI 0.28-0.77, p=0.106), fruits (OR 0.44, 95% CI 0.26-0.74, p <0.001), soybean product (OR 0.45, 95% CI 0.24-0.86, p=0.311), coffee (OR 0.47, 95% CI 0.23-0.95, p 0.004), and egg (OR 0.4, 95% CI 0.23-0.71, p=0.002).

Conclusion: Greater consumption of vegetables, fruit, soybean products, coffee, and eggs is associated with a lower risk of breast cancer. This study provides evidence of breast cancer prevention by increasing the intake of these dietary groups, especially in LMICs.