Dietary Carbohydrate, Glycemic Index, Glycemic Load, and Breast Cancer Risk Among Mexican Women.

BACKGROUND: Very few studies have focused on the relationship among dietary carbohydrates, glycemic index (GI), glycemic load (GL), and breast cancer risk in Latin American women. Our objective was to assess the associations among dietary carbohydrate, GI, GL, and risk of breast cancer, and to further investigate these associations by levels of overweight/obesity and physical activity. METHODS: We used data from a Mexican population-based case-control study. We recruited a 1,000 women with incident breast cancer and 1,074 matched control women ages 35 to 69 years between 2004 and 2007. We used conditional logistic regression models and energy-adjusted carbohydrates, GI, and GL using the residual method. RESULTS: Total carbohydrate intake was associated with an increased risk of breast cancer among premenopausal women. The odds ratio in the highest versus the lowest quartile was 1.3 (95% confidence interval = 1.0, 1.7; P trend = 0.03). In stratified analyses by body mass index (BMI), the positive association between carbohydrate and risk of premenopausal breast cancer was only observed among overweight women. The odds ratio comparing the top with the bottom quartile was 1.9 (95% confidence interval = 1.2, 3.0; P trend = 0.01) among women with BMI ≥ 25 kg/m. No association was observed among women with BMI < 25 kg/m. CONCLUSIONS: Our findings suggest that high carbohydrate diets are associated with an increased risk of breast cancer among premenopausal Mexican women.

Anthropometry, silhouette trajectory, and risk of breast cancer in Mexican women.

BACKGROUND: Obesity has been associated with breast cancer risk in the Caucasian population but the association remains unclear in the Hispanics. Previous studies conducted among Hispanics in the U.S. have shown inconsistent results. PURPOSE: The association between anthropometry, body shape evolution across lifetime, and the risk of breast cancer was assessed using a multi-center population-based case-control study conducted in Mexico. METHODS: One thousand incident cases and 1074 matched control women aged 35-69 years were recruited between 2004 and 2007, and analyzed in 2011-2012. Conditional logistic regression models were used. RESULTS: Height was related to an increased risk of breast cancer in both premenopausal (p trend=0.03) and postmenopausal women (p trend=0.002). In premenopausal women, increase in BMI; waist circumference (WC); hip circumference (HC); and waist-hip ratio (WHR) were inversely associated with breast cancer risk (p trends<0.001 for BMI and WC, 0.003 for HC, and 0.016 for WHR). In postmenopausal women, decreased risks were observed for increased WC (p trend=0.004) and HC (p trend=0.009) among women with time since menopause <10 years. Further analysis of body shape evolution throughout life showed strong and significant increase in risk of breast cancer among women with increasing silhouettes size over time compared to women with no or limited increase. CONCLUSIONS: These findings suggest that anthropometric factors may have different associations with breast cancer risk in Hispanic women than in Caucasian women. This study also shows the importance of considering the evolution of body shape throughout life.