Double-positive in triple-negative? How significant is basal cytokeratin expression in breast cancer?

Basal-like breast cancer has an unfavorable prognosis. Immunohistochemically, they are predominantly estrogen receptor (ER), progesterone receptor (PR) and CerbB2 receptor (HER2)-negative, show expression of Cytokeratins (CKs) 5/6, CK14, CK 17 and P-cadherin and are associated with germline BRCA1 mutations. Immunohistochemistry (IHC) is an easily available and relatively inexpensive technique that can detect this cancer subtype, and patients can benefit from aggressive management protocols. The aim of this study was to evaluate the expression of CK 5/6 and CK14 in breast cancer and its correlation with age, tumor grade, tumor size, histomorphological pattern, nodal status, ER, PR, HER2/neu, and Ki-67 index.

Fifty treatment-naїve patients of breast carcinoma who underwent surgery constituted the study group. No core cut biopsy specimens were considered. Histopathological examination along with IHC was performed for CK5/6, CK14, ER, PR, HER2/neu, and Ki-67. Comparison between the expression of CK5/6 and CK14 with age, tumor size, tumor grade, histological subtype, nodal status, ER, PR, HER2/neu, and Ki-67 expression was performed using SPSS 20 version software.

Twenty-six percent of cases showed expression of CK5/6 and CK14. CK5/6 and CK14 expression correlated strongly with ER/PR negativity, young age, and Ki-67 proliferative index greater than 15%. No significant association with HER2/neu negativity was demonstrated. Contrasting results were obtained between CK5/6 and CK14 expression with respect to tumor grade and lymph node status.

IHC can be used to identify patients with basal phenotype breast cancer with good sensitivity and specificity, and such patients can benefit from aggressive management.