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- Pregnancy and Breast Cancer: Maternal and Fetal Complications of Chemotherapy
Breast cancer is the most common cancer in women - it accounts for 33% of new cancer cases every year. It affects more than 60,000 women a year in France, but its survival rate is 87% at the five-year mark. It should be noted that less than 1% of breast cancers occur in men. Cancer cells may be contained within the lobules (the group of glands that produce milk) or ducts of the breast (which carry milk), or they may invade nearby tissues, such as lymph nodes under the armpit. In the first case, we are talking about carcinoma in situ and in the second - of invasive carcinoma. Cancer cells can then pass into the blood and cause metastases.
Breast cancer in pregnant women poses specific diagnostic and therapeutic challenges. By relying on VigiBase, a global pharmacovigilance database, a statistical study conducted at Institut Curie focused on the complications reported in pregnant women treated with chemotherapy and in their newborns. The objective was to identify the most frequently reported side effects with the chemotherapies used in breast cancer, whether they concern pregnancy, the mother or the child.
In total, more than 3,000 statements from pregnant patients exposed to anticancer treatments between 2009 and 2022 were studied. Certain molecules appear associated with complications such as intrauterine growth retardation, neonatal hematological disorders, infections or certain congenital malformations.
And the risks seem to be particularly significant when exposure occurs in the first trimester of pregnancy.
"Our results highlight useful signals to guide clinical surveillance and deepen the evaluation of the safety of treatments administered during pregnancy. Oncologists now have new avenues to better identify the treatments that can be administered during pregnancy, taking into account the specific risks associated with each molecule and the time of exposure ", emphasizes Dr. Rayan Kabirian, medical oncologist at Institut Curie.
Learn more about breast cancers
Maternal and neonatal complications associated with breast cancer systemic treatments: A VigiBase disproportionality analysis study – Poster session (Breast Cancer—Local/Regional/Adjuvant), Dr Rayan Kabirian – june 1 2026
