Article Type

Original Study


Objective The aim of this study was to evaluate the relationship between immunohistochemical (IHC) expression of carbonic anhydrase IX (CA IX) and the standard clinicopathological features of breast carcinoma (BC) in Egyptian patients. Background BC in Egyptian patients has specific features of a poor prognosis, such as higher stage at presentation and higher grade than that in developed countries. Hypoxia is present in most solid tumors and is associated with resistance to chemotherapy and radiotherapy as well as a more malignant phenotype. The CA IX level is elevated in response to hypoxia and is involved in tumor development and progression by regulating cellular activities, such as growth, survival, and adhesion. Patients and methods This retrospective study was carried out on 56 archival cases of Egyptian BC patients for the evaluation of IHC expression of CA IX. Results Fifty-one cases out of 56 (91.1%) showed positive expression of CA IX, whereas five (8.9%) cases showed negative expression. There were significant differences between CA IX IHC expression and tumor stage and stromal response (P = 0.03 and 0.002, respectively) as advanced stage and desmoplastic stroma in favor of overexpression. In terms of the CA IX staining pattern, 44 (78.5%) showed cytoplasmic localization and seven (12.5%) showed membranocytoplasmic localization. Moreover, there were significant differences between the CA IX cytoplasmic and the membranocytoplasmic pattern of positive cases in mitotic count (P = 0.04) as a high mitotic count is found more often in the cytoplasmic pattern. Conclusion Hypoxia (overexpression of CA IX) in BC of Egyptian patients is associated with poor prognostic parameters such as advanced stage and desmoplastic stromal response. The cytoplasmic pattern of CA IX expression in BC has been associated with mitotically active tumors. CA IX expression has no relationship with hormonal status, HER2/neu, Ki-67 LI, and IHC subtyping. Further large-scale studies are warranted to investigate the new opportunity for CA IX targeted therapies in BC.