An observational study on the course of breast cancer that occurs during pregnancy. For comparison, young women (under 40) who are not pregnant may also participate.

Breast cancer (mammary carcinoma) is a malignant disease of the breast tissue characterized by the uncontrolled proliferation of breast cells. In recent years, the number of new cases among women under the age of 40 has risen, and there has been an observed increase in the number of pregnancies among women of advanced childbearing age. As a result, breast cancer is occurring more frequently during pregnancy. At present, however, the available data regarding the treatment of pregnant women and their unborn children is very limited.

The aim of this observational study is to collect and analyze data regarding the diagnosis, treatment, course of pregnancy, and disease progression in women with breast cancer. Participation in the study does not entail any additional treatment. The study will document the diagnostic tests and treatments performed or planned to date, the well-being of the newborn 4 weeks after delivery, and the health status of the mother and child 5 years after the start of treatment. Additionally, information will be collected from tumor tissue and placental tissue. For this purpose, data will be compared between two different groups. Group 1 consists of women with a first diagnosis of breast cancer during pregnancy, and Group 2 consists of women who are diagnosed with breast cancer before the age of 40 but are not pregnant at the time.

Women with a first diagnosis of breast cancer during pregnancy are eligible to participate in this study. Additionally, patients up to age 40 with a first diagnosis of breast cancer outside of pregnancy may participate in the study as a comparison group.