Rosenblatt K A, Thomas D B
Department of Community Health, University of Illinois, Champaign 61820, USA.
Int J Epidemiol. 1995 Jun;24(3):499-503. doi: 10.1093/ije/24.3.499.
The risk of endometrial cancer is related to oestrogen levels, showing an increased risk with increasing endogenous or exogenous oestrogen stimulation and a reduced risk when oestrogen is opposed by progesterone. During breastfeeding, the reduction of endogenous oestrogen exposure is larger than that of progesterone, suggesting that breastfeeding may possibly reduce the risk of endometrial cancer.
The relationship between lactation and endometrial cancer was assessed in data from six countries, including four developing countries, that were collected for a multinational hospital-based case-control study conducted between 1979 and 1988. In all, 136 cases were compared with 933 controls matched on age, hospital, and year of interview. Standardized questionnaires, administered in the local language, ascertained information on the length of time breastfed, age started and stopped breastfeeding, reproductive and contraceptive practices, and other risk factors for endometrial cancer. Conditional logistic regression was used to control for the confounding effects of gravidity and age at menarche.
Significant decreasing trends in risk were observed with increasing duration of lactation, and with months of breastfeeding per pregnancy. Risk was lowest in women who had most recently lactated, and the apparent protective effect declined with time since cessation of breastfeeding, so that there was no evidence for a protective effect after age 55 even in women who had breastfed for over 5 years.
The long-term lactation that takes place in developing countries probably reduces the risk of endometrial cancer, but this effect may not persist into the ages at which this disease is most common.
子宫内膜癌的风险与雌激素水平相关，内源性或外源性雌激素刺激增加时风险上升，而当雌激素受到孕激素拮抗时风险降低。在哺乳期，内源性雌激素暴露的减少幅度大于孕激素，这表明母乳喂养可能会降低子宫内膜癌的风险。
在1979年至1988年进行的一项基于医院的多国病例对照研究中，收集了六个国家（包括四个发展中国家）的数据，以评估哺乳与子宫内膜癌之间的关系。总共将136例病例与933例在年龄、医院和访谈年份上匹配的对照进行比较。使用当地语言进行标准化问卷调查，以确定母乳喂养时间、开始和停止母乳喂养的年龄、生殖和避孕措施以及其他子宫内膜癌风险因素的信息。采用条件逻辑回归来控制初潮年龄和妊娠次数的混杂效应。
随着哺乳期的延长以及每次怀孕母乳喂养的月数增加，风险呈现出显著的下降趋势。最近哺乳的女性风险最低，且自停止母乳喂养后，明显的保护作用随时间减弱，以至于即使是母乳喂养超过5年的女性，在55岁之后也没有证据表明存在保护作用。
发展中国家发生的长期哺乳可能会降低子宫内膜癌的风险，但这种作用可能不会持续到该疾病最常见的年龄阶段。
