Background <p>The diagnosis and management of breast cancer during pregnancy and lactation present significant challenges for both the patient and the medical team. These challenges stem from the need to balance maternal and fetal well-being, the complexities of diagnosis due to pregnancy-related changes in breast tissue, and ethical dilemmas that may arise when treatment decisions conflict with the patient’s wishes. Treatment plans must carefully consider both maternal and fetal health while ensuring patient autonomy through informed, shared decision-making and comprehensive psychological support.</p> Case presentation <p>This article presents the case of a 30-year-old pregnant woman diagnosed with right breast cancer at 28 weeks of gestation. She underwent a right breast mastectomy and axillary clearance during pregnancy. Although the patient received counseling, she declined to initiate adjuvant treatment during pregnancy. She delivered via cesarean section at 34 weeks of gestation, after which adjuvant therapies were commenced. This case is discussed in the context of relevant literature, providing a comprehensive review of the challenges associated with diagnosis and treatment, along with an update on current recommendations for managing pregnancy-associated breast cancer.</p> Conclusion <p>A multidisciplinary team should be involved in managing breast cancer during pregnancy and lactation, and the wishes of the patients should be taken into consideration once they have been fully informed about the situation and the risks associated with the treatment.</p>