Individualized treatment of pregnancy-associated breast cancer: a report of two cases and literature review.

Background: Pregnancy-associated breast cancer (PABC) occurs during the special physiological period of female pregnancy, requiring a clinical approach that considers both the effectiveness of maternal treatment and the safety of the baby, creating a clinical challenge. This article discusses the diagnosis and treatment of two PABC cases and provides a thorough review of existing literature to offer insights for clinical practice. Case Description: Patient A, a 41-year-old female at 30 weeks and 2 days of gestation, was diagnosed with left breast invasive carcinoma. Following one cycle of AC regimen chemotherapy, she successfully delivered a female infant at 35 weeks and 5 days of gestation. Subsequently, she received 5 cycles of THP regimen neoadjuvant therapy after childbirth. Then, she underwent left breast-conserving surgery and left axillary lymph node dissection. Postoperative pathology indicated pathologic complete response. Post-surgery, she received radiotherapy and targeted therapy. Patient B, a 33-year-old female at 27 weeks and 1 day of gestation, was diagnosed with left breast ductal carcinoma in situ (DCIS). She underwent left total mastectomy with left sentinel lymph node biopsy. Pathology post-surgery revealed intermediate-grade DCIS of the left breast concomitant with locally non-special type invasive carcinoma. No tumour metastasis was identified in the left sentinel lymph node. At 36 weeks of pregnancy, she delivered a male infant and subsequently received 4 cycles of AC regimen chemotherapy. After completing the chemotherapy, a newly formed mass was discovered in her right breast. Right breast mass mastectomy with vacuum assisted biopsy system was performed. Intraoperative pathology indicated intermediate-grade intraductal papillary carcinoma. During surgery, she underwent right total mastectomy and sentinel lymph node biopsy. Intraoperative frozen section analysis revealed the absence of tumour spread in the sentinel lymph nodes (0/8). Postoperatively, she received systematic endocrine therapy. Conclusions: Both patients had successful outcomes for the unborn babies following delivery. By prioritizing the safety of both the mother and the child, tailored breast cancer treatments were given to the two individuals, leading to effective therapy. Clinicians should increase their awareness and knowledge of PABC to avoid misdiagnosis or overlooking diagnoses.