RESUMO
BACKGROUND: To determine serum levels of circulating cell-free DNA (cfDNA) throughout the stages of endometrial proliferation and apoptosis during the menstrual cycle. MATERIALS AND METHODS: cfDNA was measured in 176 blood samples from 17 healthy volunteers taken at three different time points (menstruation, follicular and secretory phase). Additionally, blood samples from 20 newly diagnosed breast cancer patients were analysed. Quantitative real-time PCR was performed in order to quantify cfDNA fragments of 106 bp. RESULTS: In healthy individuals, levels of cfDNA did not differ significantly during the menstrual cycle. In breast cancer patients, the median cfDNA level was significantly higher compared to healthy individuals, irrespective of the cycle phase (p<0.001). CONCLUSION: The female cycle does not influence cfDNA serum level measurements. Considering the diagnostic or prognostic value of cfDNA in cancer patients, different time points of blood sampling in premenopausal women seem to be negligible.
