Pregnancy-Associated Breast Cancer: A Trimester and Subtype Based Clinical Decision Framework for the Surgeon and...

Pregnancy-associated breast cancer (PABC), defined as breast cancer diagnosed during pregnancy or within 1 year postpartum, presents unique surgical and oncologic challenges. Management requires balancing maternal outcomes with fetal safety while accounting for trimester-specific constraints and tumor biology.

We conducted a comprehensive narrative review of the literature on the management of operable PABC. Evidence was synthesized into a trimester-based clinical framework incorporating surgical approach, axillary staging, systemic therapy, tumor subtype, and reconstructive considerations.

Surgery is safe across all trimesters and remains the cornerstone of treatment. In the first trimester, mastectomy is generally preferred given contraindications to chemotherapy and radiotherapy during organogenesis. In the second and early third trimesters, both mastectomy and breast-conserving therapy with deferred postpartum radiation are feasible, and anthracycline- and taxane-based chemotherapy can be administered. Radiation therapy, endocrine therapy, human epidermal growth factor receptor 2 (HER2)-directed therapy, and immunotherapy are contraindicated during pregnancy. Management of aggressive subtypes, including HER2-positive and triple-negative disease, requires modification of standard neoadjuvant regimens because of fetal toxicity. Sentinel lymph node biopsy with technetium-99m sulfur colloid is safe, whereas blue dye should be avoided. Immediate expander-based reconstruction may be considered in select patients but is often deferred.

Optimal management of PABC requires trimester- and subtype-specific decision-making within a multidisciplinary framework. This review provides a practical, clinically applicable algorithm to guide management. When timely, guideline-concordant care is delivered, maternal outcomes approach those of nonpregnant patients.