Nutrient patterns and risk of breast cancer in Uruguay.

Objectives: To explore the role of nutrient patterns in the etiology of breast cancer (BC) among Uruguayan women.

Methods: A principal component analysis was conducted. The study included 442 newly diagnosed cases of BC and 442 hospitalized controls.

Results: Two dietary patterns derived from factor analysis and were labeled as high-meat and antioxidants patterns. Whereas the high-meat pattern was directly associated with BC risk (OR for the highest versus the lowest quartile = 3.50, 95 % CI 1.94-6.30, p-value for trend <0.0001), the antioxidants pattern displayed a protective effect (OR=0.44, 95 % CI 0.27-0.74). Its negative association was stronger for postmenopausal than for premenopausal women (OR=0.63, 95% CI 0.51-0.79 vs. OR=0.89, 95% CI 0.50-1.56, respectively). Both strata were heterogeneous (p=0.004). The high-meat pattern was more associated with BC risk among patients with family history of BC compared with participants without it, but results did not differ by histology. In contrast, the antioxidants pattern was more associated with non-ductal cancers (OR=0.50 [95 % CI 0.35-0.69]) than with ductal cancers (OR=0.72, 95 % CI 0.58-0.88, heterogeneity p-value=0.03).

Conclusions: Results support an association between the high-meat and antioxidant dietary patterns and BC risk. Furthermore, findings suggest that gene-environmental interactions may be important in BC etiology.