PROGNOSTIC SIGNIFICANCE OF RECEPTOR STATUS AND KI-67 INDEX IN RISK STRATIFICATION OF MORTALITY IN PATIENTS WITH BREAST CANCER IN THE REPUBLIC OF KAZAKHSTAN (RESULTS OF UNIVARIATE ANALYSIS)

Relevance. Breast cancer is characterized by substantial heterogeneity in clinical course and outcomes, which is largely determined by the biological diversity of tumors. Molecular biological markers, including receptor status and the Ki-67 proliferation index, play a key role in disease prognosis; however, their significance may vary across populations.

Objective: To evaluate the prognostic significance of receptor status (ER, PR, HER2) and the Ki-67 proliferation index in the risk stratification of mortality among patients with breast cancer based on the results of univariate analysis.

Materials and Methods. A retrospective cohort analysis was performed, including 729 patients with primary breast cancer registered between 2018 and 2022 according to the Almaty Cancer Registry. The primary endpoint was mortality. Statistical analysis included the chi-square test, logistic regression, and ROC analysis.

Results. ER and PR status demonstrated a statistically significant association with mortality risk (p < 0,001): negative receptor status was associated with a higher risk of death. Logistic regression revealed a protective effect of ER (Exp(B) = 0,883) and PR (Exp(B) = 0,424) expression. ROC analysis showed moderate discriminative ability for ER (AUC = 0,614) and PR (AUC = 0,622). HER2 status was not significantly associated with mortality (p = 0,531). The Ki-67 index was significantly associated with increased mortality risk (Exp(B) = 1,015 for each 1% increase; p < 0,001), demonstrating moderate prognostic accuracy (AUC = 0,606). The integrated molecular-biological phenotype was also significantly associated with outcomes (p < 0,001): the luminal A subtype showed the most favorable prognosis, whereas the triple-negative phenotype was associated with the poorest outcomes.

Conclusion. ER  and PR receptor status, as well as the Ki-67 index, are significant prognostic factors for mortality risk in breast cancer. HER2 status did not demonstrate prognostic significance in this cohort

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