Immunohistochemical Evaluation of Ki-67 and Comparison with Clinicopathologic Factors in Breast Carcinomas

Background: Patients primarily received tamoxifen based on their menopausal status due to the lack of immunohistochemistry. A recent study has shown that hormonal receptors were not correlated with menopausal status, and thus, indicating that they present limited therapeutic and prognostic significance in breast cancer management. This study aimed to evaluate Ki-67 value and analyze its association with clinicopathologic parameters in breast cancer patients. Methods: The formalin-fixed paraffin-embedded breast tissue blocks of 125 patients with primary breast carcinomas were subjected to immunohistochemical analysis using Ventana Benchmark® GX automated immunostainer. Analysis of variance and Chi-2 test were used to examine the relationship between Ki-67 and clinicopathologic variables. Results: The mean age of 125 patients included in the study was 47.7 years. The average score of Ki-67 was 56.0%. 84.8% of patients showed Ki-67 ≥ 14%. Mean scores of Ki-67 were correlated with grade (p = 0.006), PR (p = 0.026), histological type, ER, combined ER/RP, and molecular subtype (p < 0.001). Ki-67 was independent of HER2 (p = 0.402) and menopausal status (p = 0.471). The frequency of Ki-67 according to St Gallen 2011 was associated with histological type (p = 0.005), grade (p = 0.005), ER (p < 0.001), combined ER/PR (p = 0.004), and molecular subtype (p = 0.004). There was no significant relationship between the distribution of Ki-67 and the age of the patients (p = 0.859), menopausal status (p = 0.979), PR (p = 0.149), and HER2 (p = 0.597). Conclusion: Ki-67 is useful for treatment decisions in primary breast cancer patients. The high value of Ki-67 was associated with adverse clinicopathologic factors. The increased Ki-67 value should be carefully investigated in triple negative patients.