Division of Gynecologic Oncology, Department of Gynecology, IEO European Institute of Oncology IRCCS, Milan, Italy.
Department of Medical and Surgical Sciences and Biotechnology, Universita degli Studi La Sapienza, Roma, Italy.
ESMO Open. 2020 Oct;5(5):e000859. doi: 10.1136/esmoopen-2020-000859.
Breast cancer represents the most frequent neoplasm diagnosed in women of childbearing age. When the tumour is oestrogen receptor-positive, tamoxifen is among the recommended endocrine treatments. Lactating women are advised not to breastfeed while receiving tamoxifen. However, information about tamoxifen transfer into breast milk is lacking.We measured the concentration of tamoxifen and its metabolites by liquid chromatography-tandem mass spectrometry in the milk of a nursing mother that was treated for pregnancy-associated breast cancer diagnosed a few months after delivery. She was advised not to breastfeed her child and she collected milk samples for 23 days while the baby was fed with formula.Tamoxifen concentrations in milk increased reaching a maximum of 214 nM. The two active metabolitesZ-4-hydroxy-tamoxifen and Z-endoxifen, could not be quantified in milk the first days after tamoxifen intake, but increased over time and reached clinically significant levels after day 18.This study demonstrates for the first time in human that tamoxifen and its metabolites transfer into milk. Since tamoxifen has a complete oral bioavailability, a long half-life (>7 days) and may interfere with the normal development of the infant, mothers should not breastfeed during tamoxifen treatment.
乳腺癌是生育年龄妇女最常见的肿瘤。当肿瘤为雌激素受体阳性时，他莫昔芬是推荐的内分泌治疗之一。正在接受他莫昔芬治疗的哺乳期妇女被建议不要进行母乳喂养。然而，关于他莫昔芬在母乳中转移的信息尚不清楚。我们通过液相色谱-串联质谱法测量了一位患有产后几个月诊断出的妊娠相关性乳腺癌的哺乳期母亲的乳汁中的他莫昔芬及其代谢物的浓度。她被建议不要给孩子喂奶，在婴儿用配方奶喂养的 23 天里，她收集了牛奶样本。牛奶中的他莫昔芬浓度增加，达到 214nM 的最大值。两种活性代谢物 Z-4-羟基他莫昔芬和 Z-内消旋他莫昔芬在他莫昔芬摄入后的最初几天无法在牛奶中定量，但随着时间的推移而增加，在第 18 天后达到临床显著水平。本研究首次在人体中证明他莫昔芬及其代谢物会转移到乳汁中。由于他莫昔芬具有完全的口服生物利用度、长半衰期（>7 天），并且可能会干扰婴儿的正常发育，因此在接受他莫昔芬治疗期间，母亲不应进行母乳喂养。
