Clinical Practice Guidelines for Pregnancy-Associated Breast Cancer: CSBrS 2021

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Clinical Practice Guidelines for Pregnancy-Associated Breast Cancer: Chinese Society of Breast Surgery (CSBrS) Practice Guidelines 2021

Pregnancy-associated breast cancer (PABC), encompassing breast cancer diagnosed during pregnancy (BCP) and postpartum breast cancer (PBC), presents unique challenges due to the need to balance maternal and fetal safety. The 2021 guidelines from the Chinese Society of Breast Surgery (CSBrS) provide evidence-based recommendations for the diagnosis and management of PABC, emphasizing multidisciplinary collaboration and patient-centered decision-making.

Diagnostic Methods

The diagnostic approach for PABC aligns with that for non-pregnancy-associated breast cancer (non-PABC), with modifications to accommodate pregnancy-specific safety considerations.

Screening and Imaging

  1. Breast Ultrasound:
    Breast ultrasound is the primary imaging modality for BCP due to its safety and efficacy in detecting lesions in dense breast tissue. Pregnancy-induced glandular congestion and swelling further increase breast density, making ultrasound the preferred choice. Mammography is not routinely recommended during pregnancy due to limited evidence supporting its clinical utility in this context.

  2. Core Needle Biopsy (CNB):
    For lesions classified as BI-RADS 4 or 5 (suspicious or highly suggestive of malignancy) or BI-RADS 3 with high-risk factors, CNB is strongly recommended to obtain histopathological confirmation. This approach minimizes diagnostic delays and ensures accurate tumor characterization.

Distant Metastasis Evaluation

  1. Abdominal Ultrasound and Chest X-Ray:
    Abdominal ultrasound and chest X-ray (with abdominal shielding) are recommended for assessing distant metastasis in BCP. These modalities avoid fetal exposure to ionizing radiation, which is critical during pregnancy.

  2. Contraindicated Imaging:
    Radionuclide scans, computed tomography (CT), and gadolinium-enhanced magnetic resonance imaging (MRI) are strictly prohibited during pregnancy. Gadolinium crosses the placenta and poses teratogenic risks, while CT and radionuclide scans involve ionizing radiation.

Treatment Principles

The treatment strategy for PABC mirrors that for non-PABC but requires careful consideration of gestational age, tumor biology, and fetal safety.

Surgical Management

  1. Modified Radical Mastectomy:
    Modified radical mastectomy remains the standard surgical procedure for BCP, particularly during the second and third trimesters. This approach minimizes the need for adjuvant radiotherapy, which is contraindicated during pregnancy.

  2. Breast-Conserving Surgery (BCS):
    BCS is an option for select patients but requires careful planning. Postoperative radiotherapy, essential for BCS, must be delayed until after delivery due to its teratogenic effects. The guidelines emphasize the importance of multidisciplinary discussion to weigh the risks of delayed radiotherapy against the benefits of breast conservation.

  3. Sentinel Lymph Node Biopsy (SLNB):
    SLNB using technetium-99m sulfur colloid is considered relatively safe during pregnancy, though evidence remains limited. Blue dye tracers are discouraged due to risks of maternal allergic reactions.

Chemotherapy

  1. Timing and Regimens:
    Chemotherapy is contraindicated during the first trimester due to a 20% risk of fetal malformations. In the second and third trimesters, anthracycline-based regimens (e.g., doxorubicin, epirubicin) are preferred. Taxanes, while endorsed by European guidelines, are not routinely recommended in the CSBrS guidelines due to insufficient safety data.

  2. Delivery Considerations:
    Chemotherapy should be discontinued three weeks prior to planned delivery to avoid neonatal hematologic complications. Preterm delivery is not recommended solely for earlier chemotherapy initiation.

Contraindicated Therapies

  1. Endocrine Therapy:
    Tamoxifen and other endocrine therapies are prohibited during pregnancy due to risks of genital abnormalities and spontaneous abortion.

  2. HER-2 Targeted Therapy:
    Trastuzumab and other anti-HER2 agents are contraindicated due to associations with oligohydramnios and fetal renal toxicity.

  3. Radiotherapy:
    Radiotherapy is strictly avoided during pregnancy due to fetal radiation exposure risks, including growth restriction and carcinogenesis.

Postpartum and Lactation Considerations

  1. Postpartum Breast Cancer (PBC):
    PBC diagnosed within one year postpartum follows non-PABC treatment protocols, except for lactation-related adjustments.

  2. Breastfeeding:
    Breastfeeding is contraindicated during chemotherapy, endocrine therapy, or targeted therapy due to drug excretion in breast milk. Patients should discontinue lactation if systemic therapy is required.

Special Considerations and Follow-Up

  1. Genetic Counseling:
    Given the younger age of PABC patients, genetic testing for BRCA1/2 mutations is recommended to guide risk management for patients and their offspring.

  2. Long-Term Monitoring:
    Infants exposed to prenatal chemotherapy require long-term follow-up to assess developmental outcomes. Maternal follow-up should include routine oncology and obstetric evaluations to detect recurrence and manage late-effects of treatment.

  3. Multidisciplinary Care:
    Collaboration among breast surgeons, obstetricians, oncologists, and radiologists is essential to optimize outcomes. Patient preferences, including desires for future fertility, must be integrated into treatment planning.

Evidence and Consensus

The CSBrS guidelines draw from high-quality prospective studies, meta-analyses, and international consensus documents, including the NCCN and ESMO guidelines. A 77-member expert panel, comprising specialists in breast surgery, obstetrics, oncology, radiology, and pathology, developed the recommendations through a rigorous consensus process.

Conclusion

The 2021 CSBrS guidelines provide a structured framework for managing PABC, emphasizing fetal safety without compromising maternal oncologic outcomes. Key principles include the use of ultrasound for diagnosis, avoidance of radiation-based imaging, and tailored timing of chemotherapy and surgery. The guidelines underscore the importance of patient-centered care and multidisciplinary collaboration to address the complex challenges of PABC.

doi:10.1097/CM9.0000000000001686

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