Pathomic study on the correlation between carbonic anhydrase 9 expression and prognosis in hepatocellular carcinoma

BACKGROUND: Glycolytic markers such as carbonic anhydrase 9 (CA9) have been implicated in hepatocellular carcinoma (HCC) prognosis; however, sex-based differences and the underlying pathological mechanisms remain unclear. Herein, we investigated sex-stratified prognostic significance of CA9 and developed a pathomics-based predictive model. METHODS: Data from the TCGA-LIHC cohort were analyzed, to determine the optimal CA9 expression cutoff using the "survminer" package. Kaplan_Meier survival analysis and Cox regression were performed to assess sex-specific prognostic associations. Tissue segmentation was conducted using the Otsu method, and features extracted with PyRadiomics were optimized through a combined minimum redundancy maximum relevance_recursive feature elimination_Akaike Information Criterion pipeline to construct a logistic classifier. Ferroptosis-related pathways were interrogated using FerrDb V2 genes with gene set variation analysis (GSVA) and weighted gene co-expression network analysis (WGCNA). Model performance was evaluated using ROC-AUC and calibration curves. RESULTS: Patients with high CA9 expression experienced significantly shorter overall survival than those with low expression (42.37 vs. 84.4 months, P < 0.001). CA9 emerged as an independent risk factor (HR = 2.131, P < 0.001) with a more pronounced prognostic impact in males than in females (HR = 2.836 vs. 1.261, P = 0.038). The pathomics model achieved AUCs of 0.746 in the training cohort and 0.706 in the validation cohort; the predictive score (PS) strongly correlated with CA9 expression (P < 0.001). Patients in the high-PS group had reduced survival (56.17 months vs. 82.87 months; P < 0.001), with no significant sex-based difference observed (P = 0.17). Tumors with high PS exhibited TGF-β/mTOR signaling, whereas low-PS tumors demonstrated upregulated ferroptosis-related CGAS expression and enrichment of NADPH oxidase- and EGFR resistance-related pathways (P < 0.01). CONCLUSION: CA9 represents a sex-dimorphic prognostic biomarker in HCC. When combined with a pathomics model, it offers a precise framework for risk stratification and provides insight into the contribution of the glycolysis-ferroptosis axis to HCC progression.