Pregnancy and breast cancer in young women: current updates and future directions.

The relationship between pregnancy and breast cancer is complicated. On one hand, pregnancy can influence breast cancer risk and tumor biology, and on the other, a breast cancer diagnosis and its subsequent management can significantly affect fertility, family planning, and future pregnancies. This interaction presents challenges unique to young women with breast cancer (YWBC). This review provides an updated overview of YWBC and pregnancy-associated breast cancer (PABC), including the rising prevalence of YWBC, current understanding of the biology of PABC and its subtypes, and the management of PABC. We address the critical issue of how breast cancer treatment impacts family planning and future pregnancies, including current data on interrupting endocrine treatment for pregnancy. Additionally, we examine recent advancements in early-stage breast cancer as well as gaps in knowledge regarding how targeted treatments affect ovarian reserve. Finally, we highlight key areas of future research that could improve the prevention, management, and understanding of cancer treatment's impact on fertility in YWBC.