Department of Food Science and Nutrition, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
BMC Cancer. 2014 Feb 18;14:105. doi: 10.1186/1471-2407-14-105.
Increased ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) in diet or serum may have a protective effect on the risk of breast cancer (BC); however, the conclusions from prospective studies are still controversial. The purpose of this study is to ascertain the relationship between intake ratio of n-3/n-6 PUFAs and the risk of BC, and estimate the potential summarized dose-response trend.
Relevant English-language studies were identified through Cochrane Library, PubMed and EMBASE database till April 2013. Eligible prospective studies reporting the multivariate adjusted risk ratios (RRs) for association of n-3/n-6 PUFAs ratio in diet or serum with BC risk. Data extraction was conducted independently by 2 investigators; disagreements were reconciled by consensus. Study quality was assessed using the Newcastle-Ottawa scale. Study-specific RRs were combined via a random-effects model.
Six prospective nested case-control and 5 cohort studies, involving 8,331 BC events from 274,135 adult females across different countries, were included in present study. Subjects with higher dietary intake ratio of n-3/n-6 PUFAs have a significantly lower risk of BC among study populations (pooled RR = 0.90; 95% CI: 0.82, 0.99), and per 1/10 increment of ratio in diet was associated with a 6% reduction of BC risk (pooled RR = 0.94; 95% CI: 0.90, 0.99; P for linear trend = 0.012). USA subjects with higher ratio of n-3/n-6 in serum phospholipids (PL) have a significantly lower risk of BC (pooled RR = 0.62; 95% CI: 0.39, 0.97; I2 = 0.00%; P for metaregression = 0.103; P for a permutation test = 0.100), and per 1/10 increment of ratio in serum PL was associated with 27% reduction of BC risk (pooled RR = 0.73; 95% CI: 0.59, 0.91; P for linear trend = 0.004; P for metaregression = 0.082; P for a permutation test = 0.116).
Higher intake ratio of n-3/n-6 PUFAs is associated with lower risk of BC among females, which implies an important evidence for BC prevention and treatment is by increasing dietary intake ratio of n-3/n-6 PUFA. No firm conclusions from USA populations could be obtained, due to the limited numbers of USA studies.
饮食或血清中 n-3/n-6 多不饱和脂肪酸（PUFA）比例的增加可能对乳腺癌（BC）的风险具有保护作用；然而，前瞻性研究的结论仍存在争议。本研究的目的是确定 n-3/n-6 PUFA 摄入量与 BC 风险之间的关系，并估计潜在的汇总剂量反应趋势。
通过 Cochrane 图书馆、PubMed 和 EMBASE 数据库检索截至 2013 年 4 月的相关英文文献。纳入报告饮食或血清中 n-3/n-6 PUFA 比值与 BC 风险关联的多变量校正风险比（RR）的前瞻性研究。由 2 名研究者独立进行数据提取；意见分歧通过协商解决。使用纽卡斯尔-渥太华量表评估研究质量。通过随机效应模型合并研究特异性 RR。
纳入了来自不同国家的 274135 名成年女性中 8331 例 BC 事件的 6 项前瞻性巢式病例对照和 5 项队列研究。与研究人群相比，摄入较高饮食 n-3/n-6 PUFA 比值的受试者发生 BC 的风险显著降低（汇总 RR=0.90；95%CI：0.82，0.99），饮食中比值每增加 1/10，BC 风险降低 6%（汇总 RR=0.94；95%CI：0.90，0.99；P 趋势=0.012）。血清磷脂（PL）中 n-3/n-6 比值较高的美国受试者发生 BC 的风险显著降低（汇总 RR=0.62；95%CI：0.39，0.97；I2=0.00%；P 多元回归=0.103；P 置换检验=0.100），血清 PL 中比值每增加 1/10，BC 风险降低 27%（汇总 RR=0.73；95%CI：0.59，0.91；P 趋势=0.004；P 多元回归=0.082；P 置换检验=0.116）。
女性摄入较高的 n-3/n-6 PUFA 比值与较低的 BC 风险相关，这为 BC 的预防和治疗提供了重要证据，即通过增加饮食中 n-3/n-6 PUFA 的比值。由于美国研究数量有限，无法从美国人群中得出明确的结论。
