CARDIOTOXICITY IN BREAST CANCER PATIENTS: RELATIONSHIP OF HS-TROPONIN T CHANGES AND HEART FUNCTION IN CANCER TREATMENT.

Breast cancer patients (BC) have a high risk of cardiotoxicity (CT) due to a combination of cancer treatments.Cardiovascular (CV) complications lead to delay or withdrawal of BC therapy and worsen the survival. Therefore, it isimportant to detect CT at the early stages before the occurrence of cardiac dysfunction and heart failure (HF) signs.

Objective: to study the dynamic changes of high-sensitivity (hs) troponin (Tn) T (hs-TnT) level in BC patients during cancer treatment with the use of chemotherapy and radiation therapy (RT) to predict and prevent CV complications during individualized management.

Material and methods: 40 BC patients were included in the pilot study. The analysis of the dynamic changes of hs-TnT and ejection fraction (EF) of the left ventricle (LV) was performed before and within 6 months of cancer treatment. Based on the data analysis, a definition of a significant increase in hs-TnT was developed and proposed. Therise of hs-TnT was calculated by the difference (%) between its baseline level and in the 6 months of cancer treatment. BC patients are grouped into tertiles according to the hs-TnT increase: group 1 - low level (0-50 %), group 2 -moderate level (> 50-100 %), and group 3 - high level (> 100 %).

Results: Before the start of cancer treatment, LVEF did not differ significantly between groups (mean EF (62.6 ± 1.0) %)and the hs-TnT level was also within normal values (0.008±0.001 ng/ml). In 6 months of cancer treatment, LVEF waswithin the normal ranges and did not differ significantly in patients of group 1. However, in patients of groups 2and 3 - LVEF drop (δLV EF) was 5.7 % (р < 0.01) and 10.8 % (р < 0.01), consequently. According to the correlationanalysis, the percentage of increase in hs-TnT (δhs-TnT) was associated with δEF LV (r = 0.39, р < 0.05) and the useof anthracyclines (AC) (r = 0.37, р < 0.05). Using logistic regression and ROC analysis, the diagnostic threshold valueof the hs-TnT increase > 165 % was defined, which can be considered as a reliable marker of early biochemical CT,with a sensitivity of 99 % and a specificity of 56 %.

Conclusions: In BC patients, based on the level of hs-TnT increase, proposed a new early biochemical CT detectionmethod. Under the new approach, BC patients with hsTnT increase of > 165 % from baseline can be considered as areliable marker of early biochemical CT, with a sensitivity of 99 % and a specificity of 56 %.