Key words: breast cancer, young women, fertility, oncology

"Optimal treatment of young women with early breast cancer: oncological and fertility aspects"

In this thesis, it has been shown that giving chemotherapy sequentially is better than giving the same three means simultaneously. When breast cancer is diagnosed, chemotherapy can be given before or after breast surgery. Women with a large ductal type of breast cancer who received chemotherapy before surgery and in whom the effect was assessed with an MRI scan were found to be more likely to undergo breast saving surgery. In addition, it has been shown that women aged 45 to 54 who appeared to have undergone chemotherapy after 2 to 3 years of treatment with tamoxifen still had a restoration of their ovarian function during the use of a subsequent hormone therapy (aromatase inhibitor). As a result, the production of the female sex hormone resumed, while this proved unfavourable for the risk of breast cancer recurrence. Since this research, treatment with an aromatase inhibitor has been discouraged worldwide in women who have entered menopause due to chemotherapy. In very young women, we saw that the ovarian function almost always recovered. In order to reduce the risk of breast cancer recurrence, they are temporarily treated with additional medication. What is very positive, however, is that they can still become pregnant in a natural way if they wish to have children later on. Indeed, we saw that a quarter of the young women treated with chemotherapy for early stage breast cancer gave birth to a child within 5 years. Most pregnancies occurred spontaneously, without the use of frozen eggs or embryos prior to chemotherapy. With the data from this study, the treatment plan for young women diagnosed with breast cancer has been further improved.