Cytokeratin 5/6 and cytokeratin 8/18 expression in triple negative breast cancers: Clinicopathologic significance in South-Asian population

Objective: Cytokeratin 5/6 and Cytokeratin 8/18 are basal and luminal markers of breast cancer and they have pathological and prognostic significance in breast cancer. We performed Cytokeratin 5/6 and CK8/18 immunohistochemistry on 150 cases of triple negative breast cancers and association with various clinicopathological features was evaluated. Results: Positive CK5/6 expression was noted in 8% (12 cases) of TNBC while 2.4% (4 cases) showed focal positive (< 10%) and 89.3% (134) were negative with CK5/6. Complete loss of CK8/18 expression was seen in 4.7% (7 cases) while 32.7% (49 cases) revealed focal loss of CK8/18 and 62.7% (94 cases) showed intact normal expression of CK8/18. No significant association of CK5/6 and CK8/18 with various clinicopathological parameters was observed. We found a low expression of basal cytokeratin (CK5/6) in TNBC our studied population, while loss/altered expression of CK8/18 in approximately 38% of TNBC. Although no prognostic relevance of these finding was noted in our study, however these findings are different from those reported in literature in other parts of the world. Therefore we suggest a more through immunohistochemical and genomic profiling of TNBC in our population for better understanding of this disease in this part of the world.