Carbohydrates and the risk of breast cancer among Mexican women.
OBJECTIVE
High carbohydrate intake has been hypothesized to be a risk factor for breast cancer, possibly mediated by elevated levels of free insulin, estrogens, and insulin-like growth factor-1. Therefore, we conducted a population-based case-control study among a Mexican population characterized by relatively low fat and high carbohydrate intakes.


METHODS
Women ages 20 to 75 years, identified through six hospitals in Mexico City (n = 475), were interviewed to obtain data relating to diet (using a food frequency questionnaire) and breast cancer risk factors. Controls (n = 1,391) were selected from the Mexico City population using a national sampling frame.


RESULTS
Carbohydrate intake was positively associated with breast cancer risk. Compared with women in the lowest quartile of total carbohydrate intake, the relative risk of breast cancer for women in the highest quartile was 2.22 [95% confidence interval (95% CI) 1.63-3.04], adjusting for total energy and potential confounding variables (P for trend < 0.0001). This association was present in premenopausal and postmenopausal women (for highest versus lowest quartile, odds ratio 2.31, 95% CI 1.36-3.91 in premenopausal women and odds ratio 2.22, 95% CI 1.49-3.30 in postmenopausal women). Among carbohydrate components, the strongest associations were observed for sucrose and fructose. No association was observed with total fat intake.


CONCLUSIONS
In this population, a high percentage of calories from carbohydrate, but not from fat, was associated with increased breast cancer risk. This relation deserves to be investigated further, particularly in populations highly susceptible to insulin resistance.
Instituto Nacional de Salud Publica, Avenida Universidad 655, Colonia Santa Maria Ahuacatitlan, Cuernavaca, Morelos 62508, Mexico. iromieu@correo.insp.mx
Isabelle
I
Romieu
Eduardo
E
Lazcano-Ponce
Luisa Maria
LM
Sanchez-Zamorano
Walter
W
Willett
Mauricio
M
Hernandez-Avila
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D016022:Case-Control Studies; D016001:Confidence Intervals; D004032:Diet / Q000009:adverse effects; D004040:Dietary Carbohydrates / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D016017:Odds Ratio; D011159:Population Surveillance; D017698:Postmenopause; D017697:Premenopause; D012016:Reference Values; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D015996:Survival Rate
D004040:Dietary Carbohydrates