EXPRESSION OF BASAL CYTOKERATIN 5/6 AND PROLIFERATIVE MARKER (Ki67) IN BREAST CARCINOMA TISSUE AT OBAFEMI AWOLOWO UNIVERSITY TEACHING HOSPITAL COMPLEX, ILE-IFE

Abstract

Background: Breast cancer is the leading cause of cancer deaths amongst women worldwide. Breast cancer is an heterogeneous disease with varied prognostic and predictive values. The present WHO histological Classification has reduced prognostic and predictive values and is of little clinical use because more than 90% of the breast cancer will be grouped under the Invasive Ductal Carcinoma(Not Otherwise Specified). There is paucity of work done on the molecular subtypes of breast cancers and how it relates to focused care in Africans with breast cancer. We therefore embarked on a study to determine the Expression of basal cytokeratin 5/6 and Ki67 among our breast cancer cases.
Materials and Methods: This is a retrospective study of all histologically diagnosed breast cancer cases that had mastectomy between January 2011 to December 2015. Relevant information were obtained from the histology request cards. The slides of the cases were retrieved from our archives and reviewed to determine the histologic type and Nottingham grade. Sections were recut for histological type and Nottingham grading in cases where the old slides were missing. Sections were also recut from the tissue blocks of the cases for immunohistochemistry. The antibody used was for cytokeratin 5/6 and Ki67.
RESULTS: One hundred and fifty five breast cancer cases were studied. The age range of the patients were 26 to 85 years with a mean age of 52.09±12.9 years. The peak incidence was in the 5th decade of life. The male to female ratio was 1:14.5. More of these breast cancers were in the right breast (55.4%) while the left breast had 41.3%, 3.3% of these cases had bilateral breast disease. The most common histological variant (92.3%) was the invasive Ductal Carcinoma (Not Otherwise Specified). Of the breast cancer cases, 73.1% showed positive lymph node metastasis, 95.1% had tumor size greater than 2cm and 60.3% were of grade 3 Nottingham grade, 30.3% were of grade 2 Nottingham grade and just 2.6% were Nottingham grade 1. One hundred and thirty five of these cases were suitable for cytokeratin 5/6 and Ki67 immunohistochemical
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assessment. Of these cases, 41.9% were positive for cytokeratin 5/6 and 60.7% of the breast cancer cases were positive for Ki67. There was a positive correlation between Ki67 and cytokeratin 5/6 expression among our cases.
CONCLUSION: The pathologic features of breast cancers cases seen among our breast cancer cases show a high histologic grade, a high Nottingham grade, a large size at presentation and presence of lymph node metastasis. A significant proportion of these breast cancers express cytokeratin5/6 and have a high proliferative index. There is a positive correlation between cytokeratin 5/6 and Ki67. This suggest that breast cancers in this study may have an intrinsic aggressive nature and may contribute to the poor survival rate among our breast cancer patients. Research on the clinical translation of this molecular characteristics are on going and will likely lead to the development of targeted therapies for our patients.