Brinton L A, Potischman N A, Swanson C A, Schoenberg J B, Coates R J, Gammon M D, Malone K E, Stanford J L, Daling J R
Environmental Epidemiology Branch, National Cancer Institute, Bethesda, MD 20892, USA.
Cancer Causes Control. 1995 May;6(3):199-208. doi: 10.1007/BF00051791.
A population-based case-control study of breast cancer with a focus on premenopausal women under 45 years of age, conducted in three geographic regions of the United States, enabled the evaluation of risk in relation to varying breastfeeding practices. Among premenopausal parous women (1,211 cases, 1,120 random-digit-dialing controls), a history of breastfeeding for two or more weeks was associated with a relative risk (RR) of 0.87 (95 percent confidence interval [CI] = 0.7-1.0). This relationship was not altered substantially by removing from the reference group women who had problems with breastfeeding in the first two weeks, including those with insufficient milk production. Risk was not related substantially to number of children breastfed or length of breastfeeding, although a relatively low risk was observed among those breastfeeding for the longest duration examined (RR = 0.67, CI = 0.4-1.1 for an average period per child of 72 or more weeks). Women who began to breastfeed at a young age (< 22 years) experienced the greatest reduction in risk, but other timing parameters (e.g., interval since first or last breastfeeding) were not predictive of risk. Risks were not modified substantially by age or menopause status, although the number of menopausal subjects examined was limited. Use of medications to stop breast milk was unrelated to risk (RR = 1.04). The results of this study do not support the notion that breastfeeding substantially reduces breast cancer risk; however, this may reflect the fact that most of our study subjects breastfed only for limited periods of time (average breastfeeding per child of 30 weeks). Further studies are needed to clarify the relationship of breastfeeding to breast cancer risk, and to determine possible etiologic mechanisms underlying any observed associations.
在美国三个地理区域开展的一项基于人群的乳腺癌病例对照研究，重点关注45岁以下的绝经前女性，该研究得以评估与不同母乳喂养方式相关的风险。在绝经前已生育的女性中（1211例病例，1120例通过随机数字拨号选取的对照），母乳喂养两周或更长时间的病史与相对风险（RR）为0.87相关（95%置信区间[CI]=0.7 - 1.0）。通过从参照组中剔除在头两周有母乳喂养问题的女性，包括那些乳汁分泌不足的女性，这种关系并未发生实质性改变。风险与母乳喂养的子女数量或母乳喂养时长并无实质性关联，尽管在接受检查的母乳喂养时间最长的人群中观察到相对较低的风险（每个孩子平均母乳喂养72周或更长时间时，RR = 0.67，CI = 0.4 - 1.1）。在年轻时（<22岁）开始母乳喂养的女性风险降低幅度最大，但其他时间参数（例如，首次或末次母乳喂养后的间隔时间）并不能预测风险。风险并未因年龄或绝经状态而发生实质性改变，尽管接受检查的绝经后女性数量有限。使用药物停止母乳喂养与风险无关（RR = 1.04）。本研究结果并不支持母乳喂养能大幅降低乳腺癌风险这一观点；然而，这可能反映出我们的大多数研究对象仅进行了有限时间的母乳喂养（每个孩子平均母乳喂养30周）这一事实。需要进一步研究以阐明母乳喂养与乳腺癌风险之间的关系，并确定任何观察到的关联背后可能的病因机制。
