Petrakis N L, Wrensch M R, Ernster V L, Miike R, Murai J, Simberg N, Siiteri P K
Department of Epidemiology and International Health, University of California, San Francisco 94143.
Int J Cancer. 1987 Nov 15;40(5):587-91. doi: 10.1002/ijc.2910400502.
We investigated estrogen (estrone and estradiol) levels in serum and in nipple aspirates of breast fluid in relation to reproductive and menopausal characteristics in 104 normal women. In general, breast fluid and serum estrogen levels were not correlated and breast fluid estrogen levels were approximately 5 to 45 times higher than serum levels. Serum estrogen levels were lower in post-menopausal than in pre-menopausal women. In contrast, breast fluid estrogen levels were approximately the same in pre- and post-menopausal women. Breast fluid estrogen mean levels were lower in pre-menopausal parous women than in nulligravidous or nulliparous women whereas serum estrogen levels did not differ in these 3 groups. Breast fluid estrogen levels were positively correlated with months since last birth or since last breast-feeding. Estrogen levels were low in nipple aspirates of breast milk but gradually increased in breast fluid of non-lactating women over a period of several years after cessation of lactation. Serum estrogen levels did not increase with months since last breast-feeding. We were unable to evaluate the post-partum effect of pregnancy without lactation due to the small numbers of these subjects. The high concentrations of estrogen in breast fluid and the absence of a relationship to serum estrogen levels may explain why prior serum studies have failed to link variations in serum estrogens with breast cancer risk. The prolonged low levels of breast fluid estrogens following full-term birth and lactation may, in part, provide a mechanism by which parity reduces breast cancer risk.
我们研究了104名正常女性血清及乳头吸出液中的雌激素（雌酮和雌二醇）水平与生殖及绝经特征之间的关系。总体而言，乳房吸出液和血清中的雌激素水平不相关，乳房吸出液中的雌激素水平约为血清水平的5至45倍。绝经后女性的血清雌激素水平低于绝经前女性。相反，绝经前后女性的乳房吸出液雌激素水平大致相同。绝经前经产妇的乳房吸出液雌激素平均水平低于未孕或未育女性，而这三组女性的血清雌激素水平并无差异。乳房吸出液雌激素水平与末次生育或末次哺乳后的月数呈正相关。母乳的乳头吸出液中雌激素水平较低，但在停止哺乳后的几年里，非哺乳期女性的乳房吸出液中雌激素水平逐渐升高。血清雌激素水平不会随着末次哺乳后的月数增加。由于此类受试者数量较少，我们无法评估未哺乳妊娠的产后影响。乳房吸出液中高浓度的雌激素以及与血清雌激素水平缺乏关联，可能解释了为何先前的血清研究未能将血清雌激素的变化与乳腺癌风险联系起来。足月分娩和哺乳后乳房吸出液中雌激素水平长期处于低水平，可能在一定程度上为经产降低乳腺癌风险提供了一种机制。
