Larsson Susanna C, Bergkvist Leif, Wolk Alicja
Division of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Am J Clin Nutr. 2009 Jan;89(1):277-82. doi: 10.3945/ajcn.2008.26704. Epub 2008 Dec 3.
Calcium may potentially influence the risk of breast cancer because of its role in regulating cell proliferation, differentiation, and apoptosis. However, prospective studies of calcium intake in relation to breast cancer incidence are sparse.
The objective of this study was to prospectively examine and show the association, if any, of dietary calcium intake with risk of breast cancer by estrogen receptor (ER) and progesterone receptor (PR) status of the tumor.
The Swedish Mammography Cohort is a population-based prospective cohort of 61,433 women who were cancer-free at enrollment in 1987-1990. Dietary calcium intake was assessed with a food-frequency questionnaire at baseline and again in 1997. Cox proportional hazards models were used to estimate rate ratios (RRs) and 95% CIs, adjusted for breast cancer risk factors.
During an average of 17.4 y of follow-up, 2,952 incident cases of invasive breast cancer were ascertained. Dietary calcium intake was not associated with risk of overall breast cancer; the multivariate RR for the highest compared with the lowest quintile of calcium intake was 0.97 (95% CI: 0.87, 1.09; P for trend: 0.49). There was a statistically significant inverse trend for ER-negative/PR-negative (ER-/PR-) breast cancer (P for trend: 0.02); the multivariate RR for the comparison of extreme quintiles of calcium intake was 0.66 (95% CI: 0.44, 0.99). Calcium intake was not associated with ER-positive/PR-positive (ER+/PR+) or ER+/PR- tumors.
Our findings do not support an association between dietary calcium intake and overall breast cancer risk. The inverse relation between calcium intake and ER-/PR- breast cancer requires confirmation in other studies.
钙可能因其在调节细胞增殖、分化和凋亡中的作用而潜在影响乳腺癌风险。然而，关于钙摄入量与乳腺癌发病率关系的前瞻性研究较少。
本研究的目的是前瞻性地研究并显示膳食钙摄入量与肿瘤雌激素受体（ER）和孕激素受体（PR）状态相关的乳腺癌风险之间的关联（若存在关联）。
瑞典乳腺X线摄影队列是一个基于人群的前瞻性队列，由61433名女性组成，她们在1987 - 1990年入组时无癌症。在基线时和1997年再次使用食物频率问卷评估膳食钙摄入量。使用Cox比例风险模型估计率比（RRs）和95%置信区间（CIs），并对乳腺癌风险因素进行调整。
在平均17.4年的随访期间，确定了2952例浸润性乳腺癌发病病例。膳食钙摄入量与总体乳腺癌风险无关；钙摄入量最高五分位数与最低五分位数相比的多变量RR为0.97（95% CI：0.87，1.09；趋势P值：0.49）。ER阴性/PR阴性（ER - /PR - ）乳腺癌存在统计学显著的负向趋势（趋势P值：0.02）；钙摄入量极端五分位数比较的多变量RR为0.66（95% CI：0.44，0.99）。钙摄入量与ER阳性/PR阳性（ER + /PR + ）或ER + /PR - 肿瘤无关。
我们的研究结果不支持膳食钙摄入量与总体乳腺癌风险之间存在关联。钙摄入量与ER - /PR - 乳腺癌之间的负相关关系需要在其他研究中得到证实。
