Efeitos tardios no tecido ovariano de ratas Wistar após tratamento com Docetaxel e Ciclofosfamida

Abstract

Breast cancer (BC) is the second most common cancer worldwide. It is known that the highest incidence of BC occurs in postmenopausal women, however an increasing number of young women have been affected by this disease. CM treatment may include: chemotherapy, radiotherapy and/or hormonotherapy. Chemotherapy is a systemic treatment that can cause significant side effects, including the ovarian failure induced by chemotherapy (CIOF). The main consequences of CIOF are infertility, and late complications related to the reduction of estrogen, such as osteoporosis and cardiovascular disease. The chemotherapy regimen TC, adopts the combination of docetaxel with cyclophosphamide as an option by drugs that result in rate of survival free cancer, and fewer side effects. This study aimed to determine the late effects in the ovary caused by the treatment with the combination of two chemotherapy agents: docetaxel and cyclophosphamide (TC), using an animal model with Wistar rats. To check the synergism of these chemotherapy agents and thus analyze the effect of co-administration, Wistar female rats were divided into two groups: a control group and a TC group. They were subjected to euthanasia five months after the end of treatment, and their plasma and ovaries were collected. Important alterations were noted. The plasma estradiol level was significantly reduced in the TC group compared with the control group. Additionally, the number of apoptotic nuclei was higher in the TC group. The role of the inflammatory response in the development of ovarian damage was investigated, and we found an increased number of mast cells and increased expression of Tumor necrosis fator-α (TNF-α) in the TC group. The involvement of fibrosis was also investigated. The results showed that the TC group had increased expression levels of Transforming growth factor-β1 (TGF-β1), Collagen Type I (col-I) and Collagen Type III (col-III) compared with the control group. Ultrastructural analysis revealed the presence of collagen bundles in the treated group and showed that the ovarian tissue architecture was more disorganized in this group than in the control group. The results of this study indicate that the combination of cyclophosphamide and docetaxel, a recent proposed chemotherapy regimen for the treatment of CM can lead to significant changes in the ovary. The inflammatory process, triggered by the administration of chemotherapy, stimulates apoptosis and release of TGF- β1 in ovarian stroma, which induces extracellular matrix production, and subsequent, replacement of healthy tissue by fibrous tissue. The main consequence of this process is the reduction or loss of ovarian function, leading to early menopause and possible infertility. It is important to understand the mechanisms involved in the infertility provoked by the TC treatment, in order to study new methods which avoid this undesirable effect on women submitted to BC treatment.