Meta-analysis of global variations in grade of pT1 urothelial bladder cancer and supplementary evaluation of a Sri Lankan cohort

Abstract

Introduction Bladder cancer grading is fraught with ambiguity. We aimed to conduct a meta-analysis of grading of pT1 urothelial cancers and assess histopathology and outcomes in a Sri Lankan pT1 bladder cancer cohort. Patients and Method A meta-analysis of grading of pT1 urothelial cancers was conducted as per PRISMA guidelines. A second metaanalysis of the proportion of pTa/NMIBC at disease presentation was conducted to assess impact of delayed presentation on grading. Analysis was supplemented with data from a cohort of Sri Lankan patients. Results In the meta-analysis, the overall pooled pT1 HG prevalence was 75.3% [95% CI:68.3%-81.7%]. The pT1 HG prevalence was significantly higher (p=4.916878e-11) among the European, Japanese and Taiwanese studies at 90.1% [95% CI: 85.3%-94.0%] compared to the rest of the countries at 56.1% [95% CI:46.5%-65.4%]. The overall pooled pTa/NMIBC prevalence was 44.2% [95% CI:36.4%-52.1%]. The pTa/NMIBC percentage among Europe, China and Taiwan was 66.9%[95% CI:62.4%-71.2%] and it was 37.6% [95% CI:29.0%-46.6%] in Turkey and other Asian countries indicating a significant difference(P=1.08e-08). In the Sri Lankan cohort of 66 enrolled patients, 31(47%) had pT1, of which 61% were low-grade (LG). The 5-year progressionfree survival (PFS) of pT1 was 60.9%. In LG it was 85.7% and 22.2% in high-grade (HG) (P = 0.0006). Conclusion There is a global variation of percentages of pT1 LG versus HG disease in bladder cancer specimens at presentation which could be attributed to delay in treatment with stage migration, ethnic variations in tumour biology, and interobserver variability in assigning a grade of tumour, and needs further study.