Expression of Ki67 as a Prognostic Marker in Invasive Breast Carcinoma

Abstract

Introduction: Breast cancer is the most common cancer in women of developed countries. It accounts for 16% and 22.9% of cancers and invasive cancers, respectively. About 18.2% of deaths related to cancer amongst men and women have been attributed to breast cancer. Every year, more than 10,000 incipient breast cancer patients reckon to be diagnosed in India. Aim: To evaluate the role of Ki67 as a predictive biomarker in invasive breast cancer patients and to study its correlation with various molecular subtypes of breast cancer. Materials and Methods: A cross-sectional and descriptive study, of 100 cases of breast carcinoma coming to Histopathology section in Department of Pathology, Himalayan Institute of Medical Sciences, Swami Rama Himalayan University, Dehradun, India, was carried out over a period of one year, from 2013 to 2014. Patients were randomly selected for the study. Results: Sixty nine patients showed high proliferating index of Ki67 (>30%), followed by 20% patients that showed low proliferating index (≤15%) and 11% patients showed intermediate proliferating index (16-30%). Maximum patients were of Luminal A subtype, of which 50% showed high proliferating index. In the Luminal B subtype, 64% patients showed high proliferating index and in the Her-2 subtype, 73.9% showed high proliferating index. Of Triple Negative Breast Cancer (TNBC) subtype 86.3% showed high proliferating index. Majority of patients were of IDC (n=94). Out of these, 64(68%) patients showed high proliferating index for Ki67 immunostaining. Out of 5 patients of ILC, 3 (60%) showed high proliferating index for Ki67 immunostaining. One case of mucinous carcinoma showed low proliferating index for Ki67 immunostaining. Conclusion: High proliferating index tumours were mostly large in size. We could not find any correlation with various molecular subtypes of breast carcinoma. Though, not statistically significant, we observed that TNBC were most aggressive and showed highest rate of proliferation and Ki67 expression. High levels of Ki67 were associated with TNBC, Her2/neu and Luminal B while low and medium levels with Luminal A subtype. Ki67 immunostaining can be used as an important biomarker for proliferation.

Keywords

• molecular markers
• proliferating index
• receptors