Background: The role of diet as a cause of breast cancer in Asian Americans has not been adequately studied.
Objective: We investigated the association between dietary patterns and breast cancer risk in Asian Americans.
Design: This population-based case-control study in Los Angeles County compared dietary patterns between 1248 Asian American women with incident breast cancer and 1148 age-, ethnicity-, and neighborhood-matched controls. The relation between dietary patterns and serum concentrations of estrogens, androgens, and sex hormone-binding globulin (SHBG) was investigated in 2172 postmenopausal control women.
Results: We used a scoring method proposed by Trichopoulou et al (1) and found that adherence to a Mediterranean diet was inversely associated with risk; the odds ratio (OR) was 0.65 (95% CI: 0.44, 0.95) in women with the highest scores (> or = 8; most adherent) compared with those with the lowest scores (0-3; P for trend = 0.009), after adjustment for key covariates. We also used factor analysis and identified 3 dietary patterns (Western-meat/starch, ethnic-meat/starch, and vegetables/soy). In a combined index of the 3 patterns, women who were high consumers of Western and ethnic meat/starch and low consumers of the vegetables/soy diets showed the highest risk (OR: 2.19; 95% CI: 1.40, 3.42; P for trend = 0.0005). SHBG concentrations were 23% lower in women with a high intake of the meat/starch pattern and a low intake of the vegetables/soy pattern than in those with a low intake of the meat/starch pattern and a high intake of the vegetables/soy pattern (P for trend = 0.069).
Conclusion: Our results suggest that a diet characterized by a low intake of meat/starches and a high intake of legumes is associated with a reduced risk of breast cancer in Asian Americans.