The clinical relevance of cut-off percentage for high-grade urothelial carcinoma within low-grade urothelial carcinoma: A determining factor?

Abstract

Aims: The aim of the study was to analyze the cut-off value for the percentage of the high-grade (HG) component that has clinical significance in urothelial carcinoma (UC).

Material and methods: The study included a total of 362 patients, mixed-grade UC (MGUC) patients were classified as Combine Group (CG) 1 based on the presence of less than 5% HG areas. High-grade papillary UC (HGPUC) patients were grouped based on HG component proportions: CG2 (≥5%-<50% HG), CG3 (≥50%-<100% HG), and pure HGPUC (PHGPUC) for 100% HG components.

Results: There was a statistically significant difference between low-grade papillary UC (LGPUC) and CG1, CG2, or CG3, as well as LGPUC and PHGPUC, in terms of cancer-specific survival (CSS) (hazard ratio (HR) = 19.85, 95% confidence interval (CI) = 2.30-171.10 P = 0.007, HR = 28.38, 95% CI = 3.50-229.97 P = 0.002, HR = 18.64, 95% CI = 2.26-153.64 P = 0.007, and HR = 35.41, 95% CI = 4.61-271.72 P < 0.001, respectively). There was no statistically significant difference between PHGPUC and CG1, CG2, or CG3 in terms of CSS.

Conclusions: These findings suggest that even the presence of less than 5% HGPUC within LGPUC significantly impacts CSS. Furthermore, the increase in the percentage of HGPUC beyond 5% does not substantially influence the CSS. Based on these findings, disclosing the percentage of the high-grade component may be crucial for future patient management and treatment.