Use of trastuzumab in treating breast cancer during pregnancy: a systematic review and meta-analysis

Trastuzumab is currently the standard treatment for human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, it is not recommended for HER2-positive breast cancer patients during pregnancy as it may jeopardize safety of the fetus. Nevertheless, there is evidence that fetuses exposed to trastuzumab in early stages of pregnancy remain healthy METHODS: To evaluate the possible effects of trastuzumab on fetus and provide evidence on the safety of trastuzumab in early pregnancy in HER2-positive breast cancer patients, we analyzed 22 studies involving 22 pregnant women and 23 fetuses.

Based on the meta-analysis, the gestational week of exposure to trastuzumab is 0-34 weeks, the average duration of use is 17 weeks, and the average gestational week of delivery is 34.3 weeks. Complications occurred in 77.27% of patients during pregnancy and 56.52% of newborns。The main complication during pregnancy was anhydramnios (68.18%), while the main complications at birth were Respiratory distress or tachypnea (30%). After an average of 25.28 months of follow-up, 17.39% (4/23) of the children died. There was no complication during pregnancy or at birth in patients treated with trastuzumab during early pregnancy (P = 0.043). Patients older than 30 who received trastuzumab during pregnancy were more likely to have neonatal complications (OR = 7.778, 95%CI = 1.2-50.424, P = 0.04).

These results suggest that trastuzumab use during pregnancy can cause pregnancy,fetal and newborn complications. However, exposed to trastuzumab only in the first trimester are less likely to have pregnancy and fetal complications. Patients with gestational age below 30 years are less likely to have neonatal complications after trastuzumab during pregnancy. Terminating pregnancy should not be the only option for such patients. But more evidence is needed to verify this conclusion.