LAUSR

e12564 Background: Triple Negative Breast Cancer (ER-, PR-, Her2/neu-., TNBC) constitutes 15-18 per cent of all malignant breast cancers. It is characterized by aggressive course and high lethality. Methods: We assessed chronobiological features of 19 patients with TNBC (medium age group 34-71). We used data of Melatonin and Cortisol circadian secretions for assessment parameters. During the month, we took blood from patients on every third day, from 02:00-04:00 pm to 02:00-04:00 a.m time intervals. The control group was composed of 14 patients with breast cancer, histological type: ER/PR+ and Her2/neu-. Results: As the result of the research, meaningful differences have been revealed between the investigated and control group. In patients with TNBC, the medium day-time concentration of Melatonin during the day was 1.1 pg/ml (normal range - up to 20 pg/ml), while at night its level increased by 4.2 pg/ml. In the control group, the average day-time level was 5.7 pg/ml, and at night - 12.5 pg/ml. Regarding Cortisol, in the investigated group, in day-time hours its average concentration in blood was 2.1 μg/dl (normal tange - 2.5 - 11.9 μg/dl, at afternoon), while at night - 0.7 μg/dl (normal range < 1.8 μg/dl, at night). In the control group, at day-time, the average cortisol concentration was 4.095 μg/dl (normal range - 2.5 - 11.9 μg/dl, at afternoon), at night - 0.94 μg/dl (normal nange < 1.8 μg/dl, Night). Conclusions: The study results have showed significant biochemical differences between ER/PR+/ Her2/neu- and TNBC- patients. Reduction of circadian secretion of Melatonin, as a major biochemical marker, directly correlates with the degree of cancer aggression, as it is seen fom the study. Furthermore, in patients whose Melatonin concentration was critically low, ductal (CK5/6+ and/or EGFR+) and metaplastic (epidermal: CK5/6+, EGFR+, Ck14+, p63+) forms were histochemically detected, which are extremely aggressive subtypes of TNBC. Regarding Cortisol levels in patients with critically Melatonin level, the Cortisol concentration was at critically low margin as well, that is considered to be the additional chronobiological marker for the aggressive course and rapid progression of cancer.