Evidence on associations between dietary intake and risk of breast cancer subtypes is limited and inconsistent. We evaluated associations of fruit, vegetable, meat, and fish consumption with risk of breast cancer overall and by molecular subtype in the Vietnamese Breast Cancer Study (VBCS).
VBCS includes 476 incident breast cancer cases and 454 age-matched controls. Dietary habits over the past five years were assessed by in-person interviews using a validated food frequency questionnaire. Associations of food groups with breast cancer were evaluated via logistic regression for overall and molecular subtype with adjustment for age, education, income, family history of cancer, menopausal status, body mass index, exercise, total energy intake, and other potential dietary confounders. Odds ratio (OR) was used to approximate relative risk.
High fruit intake was inversely associated with breast cancer risk, with adjusted ORs (95% confidence intervals) of 0.67 (0.47, 0.95) and 0.41 (0.27, 0.61) for 2nd and 3rd tertiles versus 1st tertile, respectively (Ptrend <0.001). This association was stronger for triple-negative than other subtypes (Pheterogeneity<0.001). High intake of freshwater fish was inversely associated with overall breast cancer (ORT3vsT1=0.63 [0.42, 0.95]; Ptrend =0.03). An inverse association was observed between HER-2 enriched subtype and red and organ meat intake (ORT3vsT1=0.40 (0.17, 0.93); Ptrend=0.04; Pheterogeneity=0.50).
High intakes of fruit and freshwater fish were associated with reduced breast cancer risk; association for the former was stronger for triple-negative subtype.
Our findings suggest high intakes of fruit and freshwater fish may reduce breast cancer risk among Vietnamese women.