22 March 2016 In Cancer

PURPOSE: Moderate alcohol consumption (15 g/day) has been consistently associated with increased breast cancer risk; however, the association between alcohol and mammographic density, a strong marker of breast cancer risk, has been less consistent. Less is known about the effect of patterns of alcohol intake across the lifecourse.

METHODS: Using the Early Determinants of Mammographic Density study, an adult follow-up of women born in two US birth cohorts (n = 697; Collaborative Perinatal Project in Boston and Providence sites and the Childhood Health and Development Studies in California), we examined the association between alcohol intake in early adulthood (ages 20-29 years) and at time of interview and mammographic density (percent density and total dense area). We report the difference between nondrinkers and three levels of alcohol intake. We considered confounding by age at mammogram, body mass index, geographic site, race/ethnicity, and reproductive characteristics.

RESULTS: Seventy-nine percent of women reported ever consuming alcohol. Compared to nondrinkers in early adulthood, we observed an inverse association between >7 servings/week and percent density in fully adjusted models (beta = -5.1, 95 % CI -8.7, -1.5; p for trend = <0.01). Associations with dense area were inverse for the highest category of drinking in early adulthood but not statistically significant (p for trend = 0.15). Compared to noncurrent drinkers, the association for current intake of >7 servings/week and percent density was also inverse (beta = -3.1, 95 % CI -7.0, 0.8; p for trend = 0.01). In contrast, moderate alcohol intake (>0-</=7 servings/week) in either time period was positively associated with dense area; but associations were not statistically significant in fully adjusted models.

CONCLUSIONS: Our study does not lend support to the hypothesis that the positive association between alcohol intake and breast cancer risk is through increasing mammographic density

24 February 2016 In Cancer

BACKGROUND: There is limited evidence on the association between dietary folate intake and the risk of breast cancer (BC) by hormone receptor expression in the tumors. We investigated the relationship between dietary folate and BC risk using data from the European Prospective Investigation into Cancer and Nutrition (EPIC).

METHODS: A total of 367993 women age 35 to 70 years were recruited in 10 European countries. During a median follow-up of 11.5 years, 11575 women with BC were identified. Dietary folate intake was estimated from country-specific dietary questionnaires. Cox proportional hazards regression models were used to quantify the association between dietary variables and BC risk. BC tumors were classified by receptor status. Subgroup analyses were performed by menopausal status and alcohol intake. Intake of other B vitamins was considered. All statistical tests were two-sided.

RESULTS: A borderline inverse association was observed between dietary folate and BC risk (hazard ratio comparing top vs bottom quintile [HRQ5-Q1] = 0.92, 95% CI = 0.83 to 1.01, P trend = .037). In premenopausal women, we observed a statistically significant trend towards lower risk in estrogen receptor-negative BC (HRQ5-Q1 = 0.66, 95% CI = 0.45 to 0.96, P trend = .042) and progesterone receptor-negative BC (HRQ5-Q1 = 0.70, 95% CI = 0.51 to 0.97, P trend = .021). No associations were found in postmenopausal women. A 14% reduction in BC risk was observed when comparing the highest with the lowest dietary folate tertiles in women having a high (>12 alcoholic drinks/week) alcohol intake (HRT3-T1 = 0.86, 95% CI = 0.75 to 0.98, P interaction = .035).

CONCLUSIONS: Higher dietary folate intake may be associated with a lower risk of sex hormone receptor-negative BC in premenopausal women.

24 February 2016 In Cancer

IMPORTANCE: Breast cancer is the leading cause of female cancer burden, and its incidence has increased by more than 20% worldwide since 2008. Some observational studies have suggested that the Mediterranean diet may reduce the risk of breast cancer.

OBJECTIVE: To evaluate the effect of 2 interventions with Mediterranean diet vs the advice to follow a low-fat diet (control) on breast cancer incidence.

DESIGN, SETTING, AND PARTICIPANTS: The PREDIMED study is a 1:1:1 randomized, single-blind, controlled field trial conducted at primary health care centers in Spain. From 2003 to 2009, 4282 women aged 60 to 80 years and at high cardiovascular disease risk were recruited after invitation by their primary care physicians.

INTERVENTIONS: Participants were randomly allocated to a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advice to reduce dietary fat).

MAIN OUTCOMES AND MEASURES: Breast cancer incidence was a prespecified secondary outcome of the trial for women without a prior history of breast cancer (n = 4152).

RESULTS: After a median follow-up of 4.8 years, we identified 35 confirmed incident cases of breast cancer. Observed rates (per 1000 person-years) were 1.1 for the Mediterranean diet with extra-virgin olive oil group, 1.8 for the Mediterranean diet with nuts group, and 2.9 for the control group. The multivariable-adjusted hazard ratios vs the control group were 0.32 (95% CI, 0.13-0.79) for the Mediterranean diet with extra-virgin olive oil group and 0.59 (95% CI, 0.26-1.35) for the Mediterranean diet with nuts group. In analyses with yearly cumulative updated dietary exposures, the hazard ratio for each additional 5% of calories from extra-virgin olive oil was 0.72 (95% CI, 0.57-0.90).

CONCLUSIONS AND RELEVANCE: This is the first randomized trial finding an effect of a long-term dietary intervention on breast cancer incidence. Our results suggest a beneficial effect of a Mediterranean diet supplemented with extra-virgin olive oil in the primary prevention of breast cancer. These results come from a secondary analysis of a previous trial and are based on few incident cases and, therefore, need to be confirmed in longer-term and larger studies.

TRIAL REGISTRATION: ISRCTN.org Identifier: ISRCTN35739639

27 January 2016 In Cancer

PURPOSE: Alcohol is an established breast cancer risk factor, but there is little evidence on whether the association differs between African Americans and whites.

METHODS: Invasive breast cancers (n = 1,795; 1,014 white, 781 African American) and age- and race-matched controls (n = 1,558; 844 white, 714 African American) from the Carolina Breast Cancer Study (Phases I-II) were used to estimate odds ratios (ORs) and 95 % confidence interval (CI) for pre-diagnosis drinks per week and breast cancer risk.

RESULTS: African American controls reported lower alcohol intake than white controls across all age groups. Light drinking (0 to 7 drinks per week had an elevated risk compared to light drinkers [adjusted OR, 95% CI 1.62 (1.03-2.54)]. A weaker association was observed among whites [adjusted OR, 95% CI 1.20 (0.87-1.67)]. The association of >7 drinks per week with estrogen receptor-negative [adjusted OR, 95% CI 2.17 (1.25-3.75)] and triple-negative [adjusted OR, 95% CI 2.12 (1.12-4.04)] breast cancers was significant for African American, but not white women. We observed significantly elevated ORs for heavy intake at ages 50 years of age for African American women only. We found no evidence of statistical interaction between alcohol intake and oral contraceptive use or smoking.

CONCLUSIONS: Drinking more than seven alcoholic beverages per week increased invasive breast cancer risk among white and African American women, with significant increases only among African American women. Genetic or environmental factors that differ by race may mediate the alcohol-breast cancer risk association.

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