The relationship between carbonic anhydrase IX (CAIX) and patient survival in breast cancer: systematic review and meta-analysis.

PURPOSE: Hypoxia is a characteristic of many solid tumours and an adverse prognostic factor for cancer therapy. Hypoxia results in upregulation of carbonic anhydrase IX (CAIX) expression, a pH-regulating enzyme. Many human tissue studies have examined the prognostic value of CAIX expression in breast cancer but have yielded inconsistent results. Therefore, a systematic review and meta-analysis was undertaken to assess the prognostic value of CAIX expression for breast cancer patients. METHODS: The electronic databases were systematically searched to identify relevant papers. The clinical outcomes included disease-free survival (DFS), recurrence-free survival (RFS) and overall survival (OS) in breast cancer patients. Review Manager version 5.4 was employed to analysis data from 23 eligible studies (containing 8390 patients). RESULTS: High CAIX expression was associated with poorer RFS [HR = 1.42, 95% CI (1.32-1.51), p < 0.00001], DFS [HR = 1.64, 95% CI (1.34-2.00), p < 0.00001], and OS [HR = 1.48, 95% CI (1.22-1.80), p < 0.0001]. Heterogeneity was observed across the studies. There was an effect of the CAIX antibody employed, scoring methods, and tumour localisation on CAIX expression. CONCLUSION: CAIX overexpression was significantly associated with poorer RFS, DFS, and OS in breast cancer patients. However, further work in high quantity tissue cohorts is required to define the optimal methodological approach.

The Relationship Between the Tumor Cell Expression of Hypoxic Markers and Survival in Patients With ER-positive Invasive Ductal Breast Cancer.

The prognostic significance of hypoxia markers, hypoxia-inducible factor-1α (HIF-1α), hypoxia-inducible factor-2α (HIF-2α), and carbonic anhydrase IX (CAIX), was investigated in estrogen receptor (ER)-positive breast cancer patients. Immunohistochemistry determined the expression of makers in two independent ductal ER-positive cohorts (Training set, n=373 and Validation set, n=285) and was related to clinicopathological parameters and disease-free survival (DFS). In the training cohort, nuclear HIF-1α (1) was independently associated with poorer DFS in luminal A tumors [hazard ratio (HR) = 0.53 95% confidence interval (CI): 0.30-0.94, p=0.030]. In the validation cohort, both HIF-1α (1) and CAIX were independently associated with decreased DFS in the entire cohort (HR = 1.85 95% CI: 1.10-3.11, p=0.019; HR = 1.74 95% CI: 1.08-2.82, p=0.023), in luminal A disease (HR = 1.98 95% CI: 1.02-3.83, p=0.042), and in luminal B disease (HR = 2.75 95% CI: 1.66-4.55, p<0.001), respectively. Taken together, elevated cytoplasmic HIF-1α (1) expression was an independent prognostic factor in luminal A disease, whereas CAIX was an independent prognostic factor in luminal B disease. Further work in large tissue cohorts is required.

The relationship between hypoxia-inducible factor 1α (HIF-1α) and patient survival in breast cancer: Systematic review and meta-analysis.

INTRODUCTION: Hypoxia is a characteristic of many solid tumours and results in an increase in expression of HIF-1α. Many studies have investigated the prognostic value of HIF-1α expression in breast cancer (BC), however, the prognostic value remains unclear. Therefore, a systematic review and meta-analysis was undertaken to determine the prognostic value of HIF-1α in BC patients. METHODS: The electronic databases PubMed and Web of science were systematically searched to identify relevant papers. The clinical outcomes included disease-free survival (DFS), recurrence-free survival (RFS) and overall survival (OS) in BC patients. Review Manager version 5.4 was employed to analysis data from 30 eligible studies (containing 6201patients). RESULTS: High expression of HIF-1α was associated with poorer DFS and OS. There was an effect of survival analysis, study region, antibodies used, scoring and threshold methods on HIF-1α expression. CONCLUSION: HIF-1α overexpression was significantly associated with poorer DFS and OS in breast cancer patients.