RESUMEN
Prognosis for some histological variants of a rare breast disease, phyllodes tumors, is evaluated. The prognostic potential of some molecular biological factors significantly correlating with breast cancer prognosis is evaluated on a unique clinical material (244 cases with benign, intermediate, and malignant phyllodes tumors). The development of benign phyllodes tumor relapse directly correlated with the number of G0/1-phase cells and inversely correlated with the number of cells in the G2+M and S phases. The level of steroid hormone receptors in phyllodes tumors cannot serve as a prognostic marker predicting the disease course. The presence of somatic mutations of TP53 gene and loss of heterozygosity of specific intragenic loci in the tumor correlate with the development of disease relapse (p<0.05).