Abstract
Introduction
Chromophobe renal cell carcinoma (CHRCC) is the third most common RCC subtype, typically with a favorable prognosis, though some cases show aggressive behavior. The prognostic utility of tumor grading in CHRCC remains controversial, particularly regarding the Fuhrman grading system due to inherent nuclear atypia. The Paner et al. three-tiered chromophobe tumor grading (CTG) system addresses these limitations by incorporating nuclear crowding and anaplasia. This study evaluates CTG’s prognostic value versus Fuhrman grading and other factors like pT stage, sarcomatoid differentiation, and tumor necrosis.
Materials and methods
This retrospective study analyzed 51 patients who underwent radical nephrectomy for chromophobe renal cell carcinoma (CHRCC) at Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, between 2014 and 2019. Tumors were graded using the Fuhrman and Paner CTG systems. Prognostic factors assessed included pT stage, sarcomatoid differentiation, and tumor necrosis. Statistical analysis used Chi-square and independent sample T-tests. Survival analysis was performed using Kaplan-Meier curves to determine overall survival (OS), recurrence-free survival (RFS), and distant metastasis-free survival (DMFS).
Results
Most cases (68.6%) were CTG grade 1–2, and 31.4% were grade 3. All adverse events occurred in grade 3 tumors (DMFS 75%, RFS 93.8%, CSS 87.5%). Grades 1–2 had 100% survival. Fuhrman grading showed less prognostic relevance due to inconsistent results. Tumor necrosis and advanced pT stage correlated with poor outcomes. Sarcomatoid differentiation appeared in one of four progressing cases.
Conclusion
The Paner CTG system effectively stratifies CHRCC patients by prognostic risk. It outperforms Fuhrman grading in predicting adverse outcomes. Higher tumor grade, necrosis, and advanced pT stage all significantly correlated with poor prognosis. These findings support adopting the Paner grading system for CHRCC to improve risk stratification and clinical decisions. Larger studies are warranted to validate these results.