Risk of Breast Cancer Among French-Canadian Women, Noncarriers of More Frequent BRCA1/2 Mutations and Consumption of Total Energy, Coffee, and Alcohol

Although the connection between diet, lifestyle and hormones suggests that nutritional and lifestyle factors may exert an influence in the etiology of breast cancer, it is not clear whether these factors operate in the same way in women without BRCA gene mutations. A nested case-control study was conducted in a cohort of French-Canadian women, with 560 members involving 280 nongene carriers of mutated BRCA gene affected by breast cancer and 280 nonaffected and nongene carriers of mutated BRCA gene. A validated semi-quantitative food frequency questionnaire was used to ascertain dietary intake, and a core questionnaire, to gather information on lifestyle risk factors. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in logistic regression models. It was found that energy intake > 2,057 Kcal/day was significantly and positively related to breast cancer risk (OR = 2.54; 95% CI: 1.67-3.84; p = 0.01). Women who drank more than eight cups of coffee per day had an increased risk of breast cancer: OR = 1.40 (95% CI: 1.09-2.24; p = 0.03). Subjects who drank > 9 g of alcohol (ethanol) per day had an increased risk of breast cancer: OR = 1.55 (95% CI: 1.02-2.37; p = 0.04). In addition, a positive and significant association was noted between the consumption of beer, wine and spirits, and breast cancer risk. The ORs were 1.34 (95% CI: 1.28-2.11; p = 0.04) for more than two bottles of beer per week, OR = 1.16 (95% CI: 1.08-2.58; p = 0.05) for > 10 oz of wine per week and OR = 1.09 (95% CI: 1.02-2.08; p = 0.05) for > 6 oz of spirit per week, respectively. Intakes of other nutrients and dietary components were not significantly associated with nongene carrier breast cancer risk. This study provides evidence that total energy intake, coffee, and alcohol consumption may play a role in breast cancer risk.