"Highlights

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  Breast cancer risk is increased postpartum, but has a long-term protective effect.

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  Younger patients present with more aggressive breast tumor biology.

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  Breast cancer risk is increased postpartum but pregnancy has a long-term protective effective, especially for estrogen receptor positive breast cancers.

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  Mammography is safe during pregnancy and lactation.

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  Magnetic resonance imaging of the breast during pregnancy should be avoided unless absolutely necessary.

Abstract

Breast cancer is the most common malignancy among women of reproductive age, with increasing incidence influenced by delayed childbearing, genetic predisposition, and lifestyle factors. Younger patients often present with more aggressive tumor biology, including hormone receptor negativity and HER2 positivity. Pregnancy exerts a complex effect on breast cancer risk: the risk initially increases postpartum, particularly in older first-time mothers and those with a family history, but pregnancy has a long-term protective effect, mainly for estrogen receptor positive cancers. Pregnancy-associated breast cancer often presents at later stages and with aggressive features as physiologic changes in pregnancy and lactation increase breast density and ductal and lobular proliferation, which can complicate clinical and radiologic evaluation. Because of this, early risk assessment and tailored imaging are crucial for timely diagnosis. This review defines high-risk factors for breast cancer, and the management of these individuals during pregnancy and lactation.

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