Familial breast cancer, pregnancy and cardiotoxicity associated with the use of doxorubicin and reaction with trastuzumab

Breast Cancer (BC) is a neoplasm with the highest prevalence in women in Brazil and worldwide. Pregnancy-associated with BC is defined as that which occurs during pregnancy or within 1 to 2 years postpartum. The objective is to present a clinical case of a young patient with a history of familial BC who had cancer during pregnancy. The patient had cardiotoxicity after using doxorubicin and trastuzumab.She was a young patient within infiltrating ductal carcinoma in the right breast She was diagnosed within nine weeks of gestation and submitted to neoadjuvant chemotherapy with AC protocol (doxorubicina and cyclophosphamide) and mastectomy. Developed left atrial overload after treatment and still responding to hypersensitivity to trastuzumab.The patient presented an alteration in the electrocardiogram (ECG) after the use of doxorubicin. The exam was repeated and the ECG was normal. Trastuzumab was started after delivery and the patient had a hypersensitivity reaction. Administration of trastuzumab was stopped and hydrocortisone was administered. The patient showed improvement in symptoms with cessation of trastuzumab.Although anthracycline-induced cardiotoxicity and hypersensitivity reactions to trastuzumab are common reactions, there are few studies on the effects of these drugs in patients with Gestational breast cancer (GBC). Monitoring cardiotoxicity in breast cancer treatment in pregnant patients is essential to avoid two complications: for the pregnant woman and the fetus.