OSTEOPROTEGERIN AS A PREDICTIVE MARKER OF THE COURSE OF BREAST CANCER

Despite the considerable progress in research of breast cancer (BC), taking into consideration the division into molecular subtypes, the mechanics of metastasis development in BC patients are not definitely investigated, especially at favorable prognosis. Research of new informative diagnostic and prognostic markers represents the modern problems of BC pathology in a new way.

This paper is devoted to study of osteoprotegerin (OPG) expression levels in tumor cells in BC patients. The study covered 83 female patients with regional BC (T2–4N0–3M0), treated from 2003 to 2010. The inclusion criteria were histologically proved diagnosis of invasive BC, age over 18 y. o., ECOG 0 or 1. In order to study OPG levels, we carried out immune histochemical test, which was carried out according to standard protocol on the sections of biopsy material. The OPG antibody from GeneTex, used in the study, was rabbit polyclonal, dilution 1:1000, incubation time – 30 minutes. Vizualization system was Real EnVision, anti-rabbit (by DAKO, Denmark). Immunohistochemical staining was studied by counting of number of positive cells in reference to total number of malignant cells. Expression over 50 % of cells was regarded as high, less than 50 % – as low. Average value of OPG expression level was 49 %, median – 50 %. Minimal value – 0 %, maximum value – 90 %. The patients were divided into 2 groups according their expression levels: Group 1 – OPG (high) expression (more than median), Group 2 – OPG (low) expression (less than median). OPG (high) Group was made by 47 patients, OPG (low) Group – by 36. When analyzing clinical and pathological characteristics of BC patients, taking into consideration OPG expression, there were noticed no reliable differences with respect to availability  or absence of affected regional lymph nodes, category T and Ki-67 indice. The group with positive estogen-progesteron receptors showed reliably more often the high values of OPG than the group with negative receptors (p < 0,05). When analyzing the duration till the progression and overall survival, a difference between the survival and time to progression (rise of metastases) in patients with low OPG levels and the same exponents in patients with high OPG levels was established.

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