How to manage breast cancer in a pregnant patient?

From the Guidelines

Breast cancer in pregnant patients should be managed with a multidisciplinary approach, prioritizing maternal and fetal well-being, and treatment should be individualized based on the cancer subtype, gestational age, and patient preferences, as recommended by the most recent guidelines 1.

Key Considerations

• Treatment decisions should be made in a specialized center with a multidisciplinary team, including oncologists, obstetricians, and neonatologists, to balance maternal and fetal risks 1.
• Chemotherapy can be administered during the second and third trimesters, with standard regimens including anthracycline-based combinations and taxanes, but should be avoided during the first trimester due to the risk of miscarriage and fetal malformations 2, 1.
• Chemotherapy should be discontinued 2-3 weeks before delivery to avoid maternal and neonatal neutropenia, with specific timing depending on the chemotherapy regimen, such as paclitaxel or doxorubicin/epirubicin/cyclophosphamide 1.

Cancer Subtype-Specific Recommendations

• For endocrine-sensitive breast cancer, hormonal agents are contraindicated during pregnancy, and treatment should be individualized based on the gestational age and cancer stage, with options including observation until delivery or chemotherapy during the second and third trimesters 2.
• For HER2-positive breast cancer, HER2-targeted agents are contraindicated during pregnancy, and treatment should include anthracycline-based chemotherapy during the second and third trimesters, with trastuzumab added after delivery 2.
• For triple-negative breast cancer, treatment should include anthracycline-based chemotherapy during the second and third trimesters, with taxanes added in sequence if needed 2.

Delivery and Postpartum Care

• Vaginal delivery should be aimed for, as there is no absolute obstetric or oncological contraindication, and the reported higher caesarean section rate is due to non-obstetrical indications or physician and patient preference 1.
• Chemotherapy can resume within a few days after a vaginal birth and 7 days after caesarean section, if no evidence of infection and the patient's incision is healing well 1.
• Regular fetal monitoring is essential throughout treatment, and delivery timing should be planned to allow recovery from chemotherapy, with breastfeeding generally contraindicated during active chemotherapy but possible after treatment completion 2, 1.

From the FDA Drug Label

In reproductive studies in rats at dose levels equal to or below the human dose, nonteratogenic developmental skeletal changes were seen and were found reversible There are no adequate and well-controlled trials of tamoxifen in pregnant women If this drug is used during pregnancy, or the patient becomes pregnant while taking this drug, or within approximately two months after discontinuing therapy, the patient should be apprised of the potential risks to the fetus including the potential long-term risk of a DES-like syndrome Reduction in Breast Cancer Incidence in High Risk Women Pregnancy Category D

Management of breast cancer in pregnant patients is not directly supported by the provided drug label information for tamoxifen.

• The label states that there are no adequate and well-controlled trials of tamoxifen in pregnant women.
• It also mentions that if this drug is used during pregnancy, the patient should be apprised of the potential risks to the fetus, including the potential long-term risk of a DES-like syndrome.
• Therefore, the use of tamoxifen in pregnant women is classified as Pregnancy Category D.
• Given the lack of direct evidence and the potential risks, a conservative clinical decision would be to avoid the use of tamoxifen in pregnant patients 3.

From the Research

Management of Breast Cancer in Pregnant Patients

• Breast cancer diagnosis during pregnancy requires a multidisciplinary approach to ensure proper management and minimize risks to both the mother and the fetus 4, 5, 6.
• Surgical treatment options, such as mastectomy or breast-conservation, can be used throughout pregnancy, while radiotherapy should be postponed until after delivery 5, 6.
• Chemotherapy can be administered during the second and third trimesters, with anthracycline-based regimens considered the standard of care 4, 5, 7.
• Taxanes may also be given during the second and third trimesters with few adverse events 4, 7.
• Endocrine therapy and targeted agents are not recommended during pregnancy due to limited data on their safety 5.
• A tailored approach to treatment is required, taking into account the stage of pregnancy, especially the first trimester, and the needs of the mother and risks to the fetus 7.
• Regular fetal monitoring is highly recommended once systemic treatment is initiated, and continued monitoring of the health of individuals with prenatal exposure to chemotherapy into adulthood is recommended for possible long-term side effects 4.
• Multidisciplinary care, including high-risk obstetrics, remains the best approach to managing this complex patient population 6.