Trastuzumab use for metastatic breast cancer in pregnancy

Trastuzumab is approved for first-line treatment for breast cancer in combination with docetaxel for stage 2 tumors positive for human epidermal growth factor receptor 2. The effects of trastuzumab on the fetus are mostly unknown.

Our case report focuses on a woman who was treated for invasive ductal carcinoma 1 year before pregnancy. She presented at 20 weeks of gestation with metastases and was treated with docetaxel and trastuzumab. She underwent two cycles of chemotherapy, and an ultrasound scan at 30 weeks showed anhydramnios. There was no history of ruptured membranes. Reappearance of amniotic fluid was noted at 33 weeks of gestation, 7 weeks after cessation of treatment.

Treatment with trastuzumab during midgestation may be associated with anhydramnios.