The purpose of the study was to study cytological, biochemical (alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDG), uric acid), and immunoenzymatic parameters oncomarker CA-15-3, cancer embryonic antigen (CEA), in secretions from the ducts of the milk glands to select the method and volume of surgical treatment. In 213 patients with fibrocystic disease of the mammary glands (FCD), material was taken from the discharge from the nipples of the mammary glands, using a dispenser. The material after research was divided into four groups: 1-content without proliferative changes, 2- content with proliferative changes in secretions from the ducts of the mammary glands, 3- papillary structures were found in the secretions from the ducts of the mammary glands, 4- single cancer cells or groups of cancer cells were found in the contents of the nipples of the mammary glands. Analysis of studies showed a gradual increase in indicators towards the fourth group compared to the first; ALT increased by - 1.40 times, (313,50 – 440,01); AST increased by - 2.15, (334,03 – 721,21); LDH increased 1.87 times (1671,64 – 3294,92); Uric acid increased (2291,96 – 3813,63); SA 15-3 decreased from dec, (37965,21 - 22445,37), CEA increased by 9.34 times, (141,10 – 1318,72). A clear correlation has been established between cytological changes in the tissue of the ductal epithelium and changes in biochemical parameters in the discharge from the nipples of the mammary glands, which indicates the expediency of using this research technique for screening early forms of breast cancer, choosing tactics and the volume of surgical treatment.