PARP inhibitors during conception and pregnancy in breast cancer

Approximately 1 in 10 women diagnosed with breast cancer before the age of 35 carry germline BRCA pathogenic/likely pathogenic variants. Poly (ADP-ribose) polymerase (PARP) inhibitors have been recently approved in the treatment of both early and advanced breast cancer. However, there are no published cases of exposure to PARP inhibitors during pregnancy. Treatment with PARP inhibitors during pregnancy is currently contraindicated and can potentially harm fertility in young women with breast cancer. We here summarize all clinical and preclinical data on the effect of PARP inhibitors on pregnancy, fertility and breast-feeding to provide guidance on their optimal use in women of childbearing potential.