Breastfeeding During and After Breast Cancer Diagnosis—A Systematic Review of the Literature

<b>Background/Objectives:</b> Breast cancer diagnosis in lactating women is relatively uncommon. The term Pregnancy-Associated Breast Cancer (PABC) refers to breast cancer diagnosed during pregnancy or within the first year postpartum. There are several factors that limit the ability to breastfeed. Despite emerging evidence suggesting that breastfeeding may be feasible and should be supported in women with PABC, there is still limited evidence regarding the percentage of them who attempt breastfeeding, and the challenges they may encounter. This study aims to systematically reviewing the literature on the available evidence regarding breastfeeding in women diagnosed with PABC. <b>Methods:</b> PubMed and Scopus were systematically searched for studies on breastfeeding in PABC until 26 June 2025. Data on breastfeeding outcomes and diagnostic challenges in relation to PABC were extracted. The systematic review is registered in PROSPERO (CRD420251043141). <b>Results:</b> A total of 15 studies met the inclusion criteria and were included in this review. The results showed a scarcity of literature regarding the percentage of women with PABC who breastfeed. Existing data revealed that a small percentage successfully breastfeed. A common occurrence throughout the studies was the concern of breastfeeding during cancer treatment. In almost all cases, reduced milk production was reported, along with the co-administration of formula as a substitute for breast milk. <b>Conclusions:</b> Management of women with PABC should not be limited to oncologic treatment but should also encompass structured breastfeeding counseling and multidisciplinary support, ideally within specialized breast cancer centers. Such integrated care has the potential to optimize maternal health outcomes, improve quality of life, and promote a more favorable pregnancy and postpartum experience.