Carbonic Anhydrase IX Enzyme in Triple Negative Breast Carcinoma: Relationship with prognostic factors and response to neoadjuvant chemotherapy

Abstract

Abstract Purpose Triple negative breast carcinoma is characterized by the absence of estrogen receptor, progesterone receptor and HER2/neu receptor. Carbonic anhydrase IX (CA IX) is a tumor-associated cell surface glycoprotein that is involved in adaptation to hypoxia-induced acidosis and plays a role in cancer progression. This study aimed to investigate CA IX expression in TNBC and its relationship with treatment effect. Methods Immunohistochemical staining was performed on Tru cut biopsy materials with CA IX antibody. Positive staining was graded as low (< 10%) and high (> 10%). In addition, the relationship between tumor diameter, histological grade and the treatment effect on mastectomy materials performed after neoadjuvant treatment was evaluated. Results Immunohistochemical staining of CA IX in tumor tissues showed that 22,5% of patients (n = 9) had low staining, 77,5% (n = 31) had high staining. Statistical analysis revealed a significant difference between CA IX staining level and histological grade of the tumor, Ki-67 proliferation index (p = 0.003, and p = 0.008, respectively). However, CA IX staining level showed no significant relationship with patient age, tumor diameter and tumor localization (p = 0.975, p = 0.337 and p = 0.456, respectively). In the evaluation made using Miller Payne scoring(MPS), 9(22.5%) of the cases had a grade 2, 13(32.5%) of them had a grade 3, 12(30%) of them had a grade 4 and 6(15%) of them had a grade 5 treatment effect. Statistically, a significant difference was detected between MPS and CAIX expression (p = 0.005). Conclusion CAIX enzyme is a poor prognostic marker in TNBC cases and its overexpression reduces the response to treatment.