Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
Department of Medical Education, E-DA Hospital and School of Medicine for International Students, School of Medicine, I-SHOU University, Kaohsiung City, Taiwan.
Am J Clin Nutr. 2021 Aug 2;114(2):450-461. doi: 10.1093/ajcn/nqab097.
Epidemiologic studies examining the relations between dairy product and calcium intakes and breast cancer have been inconclusive, especially for tumor subtypes.
To evaluate the associations between intakes of specific dairy products and calcium and risk of breast cancer overall and for subtypes defined by estrogen receptor (ER) status.
We pooled the individual-level data of over 1 million women who were followed for a maximum of 8-20 years across studies. Associations were evaluated for dairy product and calcium intakes and risk of incident invasive breast cancer overall (n = 37,861 cases) and by subtypes defined by ER status. Study-specific multivariable hazard ratios (HRs) were estimated and then combined using random-effects models.
Overall, no clear association was observed between the consumption of specific dairy foods, dietary (from foods only) calcium, and total (from foods and supplements) calcium, and risk of overall breast cancer. Although each dairy product showed a null or very weak inverse association with risk of overall breast cancer (P, test for trend >0.05 for all), differences by ER status were suggested for yogurt and cottage/ricotta cheese with associations observed for ER-negative tumors only (pooled HR = 0.90, 95% CI: 0.83, 0.98 comparing ≥60 g/d with <1 g/d of yogurt and 0.85, 95% CI: 0.76, 0.95 comparing ≥25 g/d with <1 g/d of cottage/ricotta cheese). Dietary calcium intake was only weakly associated with breast cancer risk (pooled HR = 0.98, 95% CI: 0.97, 0.99 per 350 mg/d).
Our study shows that adult dairy or calcium consumption is unlikely to associate with a higher risk of breast cancer and that higher yogurt and cottage/ricotta cheese intakes were inversely associated with the risk of ER-negative breast cancer, a less hormonally dependent subtype with poor prognosis. Future studies on fermented dairy products, earlier life exposures, ER-negative breast cancer, and different racial/ethnic populations may further elucidate the relation.
研究乳制品和钙摄入量与乳腺癌之间关系的流行病学研究尚无定论，尤其是针对肿瘤亚型。
评估特定乳制品和钙的摄入量与乳腺癌总体风险以及根据雌激素受体（ER）状态定义的亚型风险之间的关联。
我们汇集了超过 100 万名女性的个体水平数据，这些女性在研究期间的随访时间最长可达 8-20 年。评估了乳制品和钙的摄入量与总体浸润性乳腺癌（n=37861 例）以及根据 ER 状态定义的亚型风险之间的关联。使用多变量随机效应模型估计了研究特异性的危险比（HR），然后对其进行合并。
总体而言，特定乳制品、膳食（仅来自食物）钙和总（来自食物和补充剂）钙的摄入与乳腺癌总体风险之间没有明显关联。尽管每种乳制品与总体乳腺癌风险呈微弱负相关（所有 P，趋势检验>0.05），但提示 ER 状态存在差异，仅在 ER 阴性肿瘤中观察到酸奶和农家/乳清干酪与风险的关联（总体 HR=0.90，95%CI：0.83，0.98，比较≥60 g/d 与<1 g/d 的酸奶和 HR=0.85，95%CI：0.76，0.95，比较≥25 g/d 与<1 g/d 的农家/乳清干酪）。膳食钙摄入量仅与乳腺癌风险呈弱相关（总体 HR=0.98，95%CI：0.97，0.99，每 350mg/d）。
我们的研究表明，成人乳制品或钙的摄入不太可能与乳腺癌风险增加相关，较高的酸奶和农家/乳清干酪摄入量与 ER 阴性乳腺癌风险呈负相关，而 ER 阴性乳腺癌是一种激素依赖性较低、预后较差的亚型。关于发酵乳制品、早期生活暴露、ER 阴性乳腺癌和不同种族/民族人群的进一步研究可能会进一步阐明这种关系。
