Michels K B, Willett W C, Rosner B A, Manson J E, Hunter D J, Colditz G A, Hankinson S E, Speizer F E
Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
Lancet. 1996 Feb 17;347(8999):431-6. doi: 10.1016/s0140-6736(96)90010-0.
The relation between breastfeeding and breast cancer risk has been examined in many studies; some have reported no association, and others a reduced risk, particularly among premenopausal women. In the only prospective cohort study, no association was found. We have assessed prospectively the association between breastfeeding and incidence of breast cancer among 89,887 women in the US Nurses' Health Study.
In 1986, participants were asked about the number of months they breastfed for all their children combined. Parous women with no history of cancer were included in this analysis. During 6 years of follow-up (513,015 person-years), 1,459 invasive breast cancer cases were diagnosed.
Relative to women who had never breastfed, no significant overall association was found--after adjusting for established risk factors for breast cancer--between a history of having breastfed and subsequent development of breast cancer (relative risk [RR] 0.93, 95% CI 0.83 -1.03). No inverse trend was observed with duration of breastfeeding; women who breastfed for 2 years of longer had a RR of 1.11 (0.90-1.38). Among women who had given birth only once, women who had breastfed their child experienced a lower incidence of breast cancer (RR 0.68, 0.46-1.00). Among premenopausal women, who tended to be near menopause due to the age structure of the cohort, the RR of breast cancer for those who had lactated was 1.16 (0.89-1.50). Premenopausal women who had lactated for 1 year or more had a RR of 1.10 (0.78-1.57).
These data suggest that there is no important overall association between breast-feeding and the occurrence of breast cancer.
许多研究都探讨了母乳喂养与患乳腺癌风险之间的关系；一些研究报告称二者无关联，另一些研究则发现风险降低，尤其是在绝经前女性中。在唯一一项前瞻性队列研究中，未发现二者存在关联。我们在美国护士健康研究中，对89887名女性进行了前瞻性评估，以研究母乳喂养与乳腺癌发病率之间的关联。
1986年，研究人员询问了参与者母乳喂养所有孩子的总月数。分析纳入了无癌症病史的经产妇。在6年的随访期（513015人年）内，共诊断出1459例浸润性乳腺癌病例。
在调整了已知的乳腺癌风险因素后，与从未母乳喂养的女性相比，母乳喂养史与后续患乳腺癌之间未发现显著的总体关联（相对风险[RR]为0.93，95%置信区间为0.83 - 1.03）。未观察到母乳喂养持续时间与风险呈反向趋势；母乳喂养2年及以上的女性RR为1.11（0.90 - 1.38）。在仅生育过一次的女性中，母乳喂养孩子的女性患乳腺癌的发病率较低（RR为0.68，0.46 - 1.00）。在绝经前女性中，由于队列的年龄结构，她们往往接近绝经年龄，进行过哺乳的女性患乳腺癌的RR为1.16（0.89 - 1.50）。绝经前进行过1年及以上哺乳的女性RR为1.10（0.78 - 1.57）。
这些数据表明，母乳喂养与乳腺癌的发生之间不存在重要的总体关联。
