Abstract
BACKGROUND: Low dietary folate intake is associated with several neoplasias, but reports are inconsistent for breast cancer. Additionally, the association of folate with breast cancer estrogen receptor (ER) status is not well established. OBJECTIVE: To determine if dietary intakes of folate, B-vitamins (B2, B6, B12) and methionine are associated with breast cancer risk and ER status in Hispanic, and non-Hispanic White women in the southwestern U.S. MATERIALS AND METHODS: Primary breast cancer cases (n = 2,325) in the 4-Corners region (Arizona, Colorado, New Mexico and Utah), diagnosed between October 1999 and May 2004, were identified through state cancer registries. Controls (n = 2,525) were frequency-matched by ethnicity and age (±5 years). Dietary intake, physical activity and other exposures were assessed using in-person interviews. Risk was assessed through multivariable and multinomial logistic regression with adjustment for relevant covariates. RESULT: While there was no overall association with breast cancer, the highest quartile of folate intake was marginally inversely associated with ER- breast cancer (Odds Ratio (OR) = 0.50, 95% CI 0.25-1.00, p for trend = 0.07). Vitamin B12 intake was inversely associated with breast cancer also (OR = 0.73, 95% CI 0.53-1.00, p for trend = 0.06), particularly for the highest quartile of ER+ breast cancer (OR = 0.67, 95% CI 0.46-0.99, p for trend = 0.06), among NHW women (OR = 0.49, 95% CI 0.29-0.81, p for trend = 0.01) and invasive breast cancer (OR = 0.63; 95% CI: 0.42, 0.93, P(trend) = 0.01). Methionine intake was also inversely associated with ER+ breast cancer (OR for 4th quartile = 0.83, 95% CI 0.66-1.03, p for trend = 0.04), primarily among Hispanic women (OR = 0.71, 95% CI 0.47-1.06, and P for trend = 0.02). CONCLUSION: Higher intake of folate is marginally associated with a lower risk for ER- breast cancer, and higher intakes of vitamin B-12 and methionine are marginally associated with a lower risk of ER+ breast cancer.