Expression of Carbonic Anhydrase-IX and Vascular Endothelial Growth Factor in Renal Cell Carcinoma and their Prognostic Significance

Abstract

Introduction: Renal Cell Carcinoma (RCC) is the most common adult renal malignancy. Histopathologically, clear cell RCC accounts for 65-70% of all RCCs. Carbonic Anhydrase-IX (CA-IX) is a transmembrane protein and takes a role in cancer development and progression. A 75-100% clear cell RCCs show CA-IX expression. But this varies with grade and stage of tumour. Vascular Endothelial Growth Factor (VEGF) is responsible for tumour angiogenesis and expressed variedly in RCCs. Both VEGF and CA-IX expression is mediated by Hypoxia Inducible Factor-1α (HIF-1α). Aim: The present study aimed to evaluate the expression of CA-IX and VEGF in respect to different grades and stages of RCC and assessing their prognostic significance. Materials and Methods: This was a cross-sectional, observational study done on 45 histopathogically diagnosed cases of RCC. It was performed in the Department of Pathology, Nil Ratan Sircar Medical College, Kolkata, West Banglore, India over a period of two years (February 2018 to January 2020). Expression of VEGF and CA-IX were studied by immunohistochemistry. Results were analysed in Statistical Package for Social Sciences (SPSS) software (version 16.0) using Pearson Chi-square test. A p-value of <0.05 was regarded as significant. Results: Out of 45 cases of RCC, 34 tumours (32 clear cell carcinoma and two multilocular cystic renal neoplasm of low malignant potential) were evaluated for CA-IX immuno expression. About 25 cases showed CA-IX positivity which inversely associated with grade and stage of RCC (p-value <0.05). The CA-IX had a diagnostic value in detecting clear cell RCC with sensitivity 73.53%, specificity 100% and accuracy 80%. With 28 (62.2%) cases of RCC showed VEGF positivity among which nine were VEGF 1+ and 19 cases VEGF 2+. The VEGF expression showed a positive association with the grade and Tumour-Node-Metastasis (TNM) stage of tumour (p-value <0.05). Finally, authors found a statistically significant inverse association between CA-IX and VEGF expression in RCCs with clear cell morphology including clear cell RCC and multilocular cystic renal neoplasm of low malignant potential (p-value=0.001). Conclusion: High grade RCCs show low expression of CA-IX and strong positivity with VEGF. Both these markers have a prognostic significance. From the therapeutic point of view, VEGF positive tumours, especially inoperable and metastatic cases, may be benefited by anti-VEGF therapy whereas CA-IX positive tumours respond well by treatment with Interleukin-2.