Use of Tamoxifen Before and During Pregnancy

For premenopausal patients with receptor‐positive early breast cancer, administration of tamoxifen for 5 years constitutes the main adjuvant endocrine therapy. During pregnancy, tamoxifen and its metabolites interact with rapidly growing and developing embryonic or fetal tissues. Information about tamoxifen and pregnancy was gathered by searching PubMed. In addition, we had access to the records of the pharmaceutical company AstraZeneca. Because these observations are retrospective and other therapies and diagnostic measures are possible confounders, a causal relationship was not established between tamoxifen treatment and pregnancy outcome. The records from AstraZeneca documented three live births with congenital anomalies and four live births without congenital anomalies related to tamoxifen treatment before pregnancy. Tamoxifen therapy during pregnancy resulted in 16 live births with congenital malformations and a total of 122 live births without malformations. The 122 live births without malformations included 85 patients from a prevention trial that did not record a single anomaly, whereas the AstraZeneca Safety Database alone reported 11 babies with congenital malformations of 44 live births. Additionally, there were: 12 spontaneous abortions, 17 terminations of pregnancy without known fetal defects, six terminations of pregnancy with fetal defects, one stillbirth without fetal defects, two stillbirths with fetal defects, and 57 unknown outcomes. The relatively high frequency of severe congenital abnormalities indicates that reliable birth control during tamoxifen treatment is mandatory. After tamoxifen use, a washout period of 2 months is advisable based on the known half‐life of tamoxifen. In case of an inadvertent pregnancy, risks and options should be discussed. 摘要 使用他莫昔芬5年是绝经前受体阳性早期乳腺癌患者的主要辅助性内分泌治疗。怀孕期间，他莫昔芬及其代谢产物与迅速增长发育的胚胎或胎儿组织相互作用。 他莫昔芬与怀孕的相关信息不仅检索自PubMed，还通过调阅阿斯利康制药公司文件获得。由于上述观察属回顾性，且其他治疗与诊断措施可能为混淆因素，因此他莫昔芬治疗与怀孕转归之间的因果关联并未确立。 阿斯利康公司文件记载了孕前他莫昔芬治疗相关的3例先天畸形活产儿和4例正常活产儿，孕期他莫昔芬治疗相关的16例先天畸形的活产儿和总计122例无先天畸形的活产儿。122例无先天畸形的活产儿中85例来自一项预防性试验，并未记录单一异常。然仅阿斯利康安全性数据库报告的44例活产儿中，就有11例先天畸形。此外还包括12例自发性流产、17例胎儿缺陷不明的终止妊娠、6例胎儿缺陷的终止妊娠、1例无胎儿缺陷的死产儿、2例胎儿缺陷的死产儿和57例转归不明。 重度先天异常相对高发表明，他莫昔芬治疗期间必须实施可靠节育。基于他莫昔芬的较长半衰期，建议其治疗后药物洗脱期为2个月。意外怀孕时应明确风险和选择。 The outcomes of pregnancies in women taking tamoxifen before conception and during pregnancy are reviewed. Because of potential confounding, a causal relationship between treatment with tamoxifen and adverse pregnancy outcome canno