Ki-67 expression in triple-negative breast cancer and its correlation with age

Purpose of the study. To analyze the correlation between the proliferative activity of atypical cells in triple-negative breast cancer (BC) and patient age. Patients and methods. The study included 80 women with a newly diagnosed BC, in whom a triple-negative surrogate molecular genetic subtype was identified based on histological and immunohistochemical examination with assessment of hormone receptor expression and Ki‑67. Statistical analysis was performed using Statistica 13.5.0.17 software (TIBCO Software Inc.). The Shapiro-Wilk test was applied to assess the normality of the distribution. Correlation between variables was evaluated using the Kendall tau rank correlation coefficient. Results. The median age of patients was 53.9 years (95 % confidence interval [CI]: 50.0–57.8) (Fig. 3). Among them, 65 % of patients were younger than 50 years and 35 % were older. The median proliferative activity, assessed by Ki‑67 expression according to the St. Gallen Consensus (2009), was 76.4 % (95 % CI: 73.28–79.66). However, this indicator varied depending on patient age. The analysis revealed a correlation between Ki‑67 expression level and patient age, with a Kendall tau coefficient of –0.449 ( p < 0.05), corresponding to a weak-to-moderate negative association. Conclusion. The analysis showed that the degree of Ki‑67 expression correlates with the age at breast cancer onset. Thus, there is a tendency toward higher proliferative activity of cancer cells in younger patients.