Diet quality and BRCA-associated breast cancer risk

Abstract

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.

Appendix

Diet quality index scoring criteria

Index	Dietary components	Foods included	Criteria	Score
AHEI	Vegetables and fruits	All vegetables except potatoes, all fruits and fruit juices	≥8 servings/d	10; 1 point less for each 10% less than the required intake for a full score
	Nuts and soy	Nuts, tofu and soymilk	1 serving/d	Same as above
	Ratio of white to red meat	White (chicken, seafood) and red (read and processed meats)	4	Same as above
	Cereal fiber		15 g/d	Same as above
	Trans fatty acids	All foods supplying trans fat	≤0.5% of total energy	10
			0.5 and <4% of total energy	1 point less for each 10% increment
			≥4% of total energy	0
	Ratio of PUFAS to SFAs		≥1	10; 1 point less for each 10% less than the required intake for a full score
	Multivitamin use		≥5 years	7.5 points for ≥ 5 years regular use and 2.5 points for all others
	Alcohol	Beer, wine, whiskey and spirits	0.5–1.5 serving/d	10; 1 point less for each 10% less or above than the required range intake for a full score
DQI-R	Grains	All grains, breads and grain products	≥9 servings/d	10; 1 point less for each 10% less than the required intake for a full score
	Vegetables and fruits	All vegetables, fruits and juices	≥7 servings/d	Same as above
	Total fat	All foods supplying fat	≤30% of total energy	10
			30.1–40% of total energy	5
			>40% of total energy	0
	SFAs	All foods supplying SFAs	≤10% of total energy	10
			10.1–13% of total energy	5
			>13% of total energy	0
	Cholesterol	All foods supplying cholesterol	≤300 mg	10
			301–400 mg	5
			>400 mg	0
	Calcium	All foods supplying calcium	≥1200 mg	10; 1 point less for each 10% less than the required intake for a full score
	Iron	All foods supplying iron	≥8 mg	Same as above
	Diet diversity	Sum of the following four food groups: grain products, vegetables and fruits, milk products, meats and alternatives	≥0.25 serving/d of each food included in a food group = 1 point	Maximum of 2.5 points for each food group; maximum of 10 for total diversity
	Diet moderation	Added fat	<25 g/d	2.5
			25.1–50 g/d	1.5
			50.1–75 g/d	1
			>75 g/d	0
		Added sugar	≤12 tsp/d	2.5
			12.1–18 tsp/d	1.5
			18.1–24 tsp/d	1
			>24 tsp/d	0
		Sodium	≤2400 mg	2.5
			2401–3400 mg	1.5
			>3400 mg	0
		Alcohol	≤1 drink/d	2.5
			1.01–1.5 drink/d	1.5
			>1.5 drink/d	0
AMED	Vegetables and fruits	All vegetables (except potatoes), fruits and juices		1 point if number of serving/d > median intake of control groups; 0 point if this criterion is not met
	Legumes	Beans, peas and tofu		Same as above
	Nuts	Nuts and peanut butter		Same as above
	Whole grains	Whole-grain ready-to-eat cereals, whole bread, wheat germ		Same as above
	Red and processed meats	Beef, pork, hamburger, bacon, hot dogs		Same as above
	Fish	Fish and seafood		Same as above
	Ratio of Mono Unsaturated Fatty Acids (MUFAs) to SFAs			1 point if value > median value of control groups; 0 point if this criterion is not met
	Ethanol	Beer, wine, whiskey and spirits	5–25 g/d	1
			<5 or >25 g/d	0
CHEI	Grains products	All grains, breads and grain and enriched products	≥9 servings/d	10; 1 point less for each 10% less than required intake for full score
	Vegetables and fruits	All vegetables, fruits and juices	≥8 servings/d	Same as above
	Milk products	Whole and low-fat milk, cheese, yogurt, cream, ice-cream	2–4 servings/d	10; 1 point less for each 10% less or above than the required range intake for a full score
	Meats and alternatives	Meats, poultry, fish, peas, beans and lentils	2–3 servings/d	Same as above

1. AHEI: Alternate Healthy Eating Index; DQI-R: Diet Quality Index-Revised; aMED: Alternate Mediterranean Diet Index; CHEI: Canadian Healthy Eating Index; SFAs: saturated fatty acids; MUFAs: