Expression of Carbonic Anhydrase -IX in Oral Submucous Fibrosis and Oral Squamous Cell Carcinoma

Abstract

Objective: Carbonic anhydrase IX (CAIX) is a protein that is associated with low oxygen levels and used as an indicator of the biological behaviour of oral squamous cell carcinoma (OSCC). However, the predictive significance of this has not yet been confirmed. Hence, the present study was  conducted to evaluate IHC expression of carbonic anhydrase IX in Oral squamous cell carcinoma, oral submucous fibrosis, and normal oral mucosa obtained from  healthy volunteers 
Material and Method: A cross-sectional study was conducted, which involved a total of 46 formalin-fixed paraffin-embedded tissue blocks that comprised the case group. Based on histopathology, 46 tissue blocks were divided into two groups: 23 cases of oral submucous fibrosis and 23 cases of OSCC. The control group was made up of tissue blocks from 23 healthy volunteers that had been fixed in formalin and embedded in paraffin. The IHC expression of CAIX was evaluated using the H score.
Results: The mean histoscore of CA IX in OSMF was 31.74±29.49 (mean ± SD), and the mean histoscore in OSCC was 113.04 ± 64.98 (mean ± SD). The NOM did not show any immunohistochemical staining for carbonic anhydrase IX. The ANOVA, when performed between the groups, showed a significant difference between the groups with a p value of 0.0001. Pair-wise comparison of three groups (OSMF, OSCC, and Normal Oral Mucosa) with mean H score using Tukey's multiple posthoc procedures showed a significant difference between the OSMF and OSCC (p = 0.0001) groups, the OSMF and NOM (p = 0.0296) groups, and the OSCC and NOM (p = 0.0001) groups. 
Conclusion:  The study revealed that Carbonic Anhydrase IX (CA9) increased its average H score as the illness progressed from OSMF to OSCC, successfully distinguishing OSMF from OSCC.