Management of HER2-positive breast cancer during pregnancy: a case report and literature review

Introduction: Breast cancer is one of the most common malignancies diagnosed during pregnancy, with an incidence of 1:3000 pregnancies. Its rising incidence is related to the trend to postpone childbearing during the last 30 years. Breast cancer during pregnancy should not be managed differently from the nonpregnant setting. Chemotherapy is reported to be safe after the first trimester, whereas trastuzumab and tamoxifen are contraindicated regardless of the trimester. Case description: A patient diagnosed with breast cancer recurrence during pregnancy was exposed to both tamoxifen and trastuzumab during the first two trimesters of pregnancy. In addition, docetaxel was administered during the second and third trimesters, without subsequent fetal malformations or obstetric complications. Conclusions: When conception occurs inadvertently during assumption of tamoxifen or anti-HER2 agents, their effects on the fetus and on the course of pregnancy are not completely understood. Further studies are needed in this setting, highlighting the importance to share clinical experiences.