Diet quality and BRCA-associated breast cancer risk

Although it has been suggested that dietary energy intake restriction may be related to reduced BRCA-associated breast cancer (BC) risk, it is currently not known whether overall diet quality could predict the BC risk among women with deleterious mutations in BRCA1 and BRCA2 (BRCA) genes who already have an elevated BC risk. To assess possible relationships between diet quality, reflected by the Alternate Healthy Eating Index (AHEI), the Diet Quality Index-Revised (DQI-R), the alternate Mediterranean Diet Index (aMED), the Canadian Healthy Eating Index (CHEI), and BRCA-associated BC risk, a case-control study was carried out within a cohort of 80 French-Canadian families with 250 members involving 89 carriers of BRCA genes affected by BC, 48 non-affected carriers and 46 non-affected non-carriers. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in unconditional logistic regression models. After adjustment for age, physical activity and total energy intake, we did not detect any association between the AHEI or aMED and BC. However, a strong and significant inverse relationship was apparent between the DQI-R and CHEI and BRCA-associated BC risk. ORs comparing the highest and lowest tertiles of diet quality scores were 0.35 (95%CI = 0.12-1.02; p = 0.034 for trend) for the DQI-R and 0.18 (95%CI = 0.05-0.68; p = 0.006 for trend) for the CHEI, respectively. These inverse associations were not the result of a link with any specific component of the diet quality indexes. These results suggest that dietary guidelines reflected by the DQI-R and CHEI may constitute preventive strategies for reducing BRCA-associated BC risk.