Analysis of calcium distribution in femur of female rats submitted to different chemotherapy regimens

The most used treatment strategies for breast cancer (BC) are surgery, chemotherapy, and/or radiotherapy. Premenopausal women undergoing adjuvant chemotherapy BC treatment have significant bone loss from the first year after the treatment. This high bone mineral density loss can lead to an increased risk of fractures. Doxorubicin associated with Cyclophosphamide (AC) is a multidrug widely used for BC treatment, although this association can cause severe side effects. Today it is been discussed the use of the Docetaxel and cyclophosphamide (TC) association for BC treatment. The influence on the bone during chemotherapy regimens that include taxanes, like docetaxel, is unknown. Data from the “Women`s Health Initiative” show that postmenopausal BC survivors have a 15% greater risk of developing fractures than women without a history of BC. In this study, it was evaluated parameters involved in osteoporosis when rats were subjected to a chemotherapy regimen (TC) and/or irradiation (IR). Female Wistar rats, 03 months old, were divided into 3 groups: control, TC+IR (G1) and AC+IR (G2). The animals were euthanized 5 after months the end of treatment and their femurs were excised and dissected. Sections of 10µm thick were used for µXRF analysis at the National Laboratory of Synchrotron Light. The uteri of these rats were collected and weighed Statistical analyzes were performed using GraphPad Prism, and values were compared using ANOVA and Tukey post-hoc test. The obtained results showed that animals from G2 had a significant reduction (p<0.05) of uterine mass when compared to control. The qualitative analysis performed by µXRF showed that the animals from G2 had iron in bone composition of the femurs. This same result was not observed in animals from G0 and G1 groups. These results suggest that early menopause occurs and osteoporosis begins, probably because of the absence, or reduced, production of estrogen. The presence of iron in the G2 samples indicates the process of osteoporosis, because according to literature, this ion is competitive with calcium ions.