Ontario Cancer Institute, Toronto, Ontario, Canada.
Cancer Res. 2011 Jan 1;71(1):123-33. doi: 10.1158/0008-5472.CAN-10-1436.
Epidemiologic data and animal experiments suggest that dietary fat may influence risk of breast cancer. To determine whether intervention with a low-fat, high-carbohydrate diet would reduce breast cancer incidence in women at increased risk of the disease, we carried out a randomized controlled trial in Canada. We recruited 4,690 women with extensive mammographic density and randomized them to an intervention group or a comparison group. The intervention group received intensive dietary counseling to reduce fat intake to a target of 15% of calories and increase carbohydrate to 65% of calories. Dietary intakes were assessed throughout using food records. Subjects were followed for at least 7 years and for an average of 10 years. The main outcome was invasive breast cancer. Percentage of calories from fat in the intervention group decreased from 30% at baseline to 20% after randomization and remained 9% to 10% lower than the comparison group throughout. There were 118 invasive breast cancers in the intervention group and 102 in the comparison group [adjusted hazard ratio = 1.19 (95% CI: 0.91-1.55)]. Analysis of food records showed that fat intake at baseline and after randomization was not associated with total breast cancer incidence. Greater weight and lower carbohydrate intake at baseline and after randomization were associated with an increased risk of estrogen receptor (ER)-positive breast cancer. Our findings suggest that a sustained reduction in dietary fat intake did not reduce risk of breast cancer in women with extensive mammographic density. Weight and carbohydrate intakes were associated with risk of ER-positive breast cancer.
流行病学数据和动物实验表明，饮食中的脂肪可能会影响乳腺癌的发病风险。为了确定低脂、高碳水化合物饮食干预是否会降低患有这种疾病风险增加的女性的乳腺癌发病率，我们在加拿大进行了一项随机对照试验。我们招募了 4690 名乳房 X 光检查密度较大的女性，并将她们随机分配到干预组或对照组。干预组接受强化饮食咨询，将脂肪摄入量减少到卡路里的 15%，并增加碳水化合物摄入量到卡路里的 65%。通过食物记录来评估整个过程中的饮食摄入量。受试者至少随访 7 年，平均随访 10 年。主要结果是浸润性乳腺癌。干预组的脂肪卡路里百分比从基线时的 30%下降到随机分组后的 20%，并在整个研究期间比对照组低 9%至 10%。干预组中有 118 例浸润性乳腺癌，对照组中有 102 例[调整后的危险比=1.19（95%可信区间：0.91-1.55)]。对食物记录的分析表明，基线和随机分组后的脂肪摄入量与总乳腺癌发病率无关。基线和随机分组后体重增加和碳水化合物摄入量减少与雌激素受体（ER）阳性乳腺癌的风险增加相关。我们的研究结果表明，持续减少饮食中的脂肪摄入并不能降低乳房 X 光检查密度较大的女性的乳腺癌风险。体重和碳水化合物的摄入量与 ER 阳性乳腺癌的风险相关。
