Managing Breast Cancer Diagnosed During Pregnancy

In 2022, the European Society of Medical Oncology (ESMO) convened a virtual consensus meeting with a multidisciplinary group of 24 medical experts from 13 countries on the management of breast cancer during pregnancy. Given the dearth of high-level evidence on this topic, the statements generated by the group were based on expert opinion. Among the most relevant consensus statements on the controversial issues addressed:

• Prognosis: The prognosis of breast cancer diagnosed in pregnant patients is similar to that in young patients with the same disease stage and subtype, so long as the cancer is appropriately managed. Studies that have carefully controlled for treatment, stage, and subtype have found similar outcomes between pregnant and nonpregnant patients.
• Chemotherapy: If indicated, chemotherapy can be administered after the first trimester, but it is contraindicated in the first trimester due to concerns about teratogenesis (estimated risk, 20%). Actual weight should be used to calculate chemotherapy dose during pregnancy.
• Radiation Therapy: For most patients, radiation therapy should be delayed until after delivery. However, radiation can be considered if postponing until delivery would have a detrimental impact on prognosis. During the first and most of the second trimester, radiation to the supradiaphragmatic region should not result in high exposure to the fetus, so long as pelvic shielding is carefully applied.
• Sentinel Node Biopsy: Several published studies point to the safety of sentinel node procedures during pregnancy; however, a low dose of technetium-labeled albumin rather than blue dye is preferred due to concerns about anaphylactic reaction with the latter.
• Other Treatments: Immune checkpoint inhibitors should be avoided during pregnancy due to concerns for an immune response against the fetus. Tamoxifen, PARP inhibitors, and HER2-directed therapy should also be avoided. Paclitaxel can be considered for patients who are not candidates for an anthracycline. Hematopoietic growth factors, such as short- or long-acting granulocyte colony-stimulating growth factor (G-CSF), can be given during pregnancy as they do not seem to confer much fetal risk.