Comparison between 1973 and 2004/2016 World Health Organization grading in upper tract urothelial carcinoma treated with radical nephroureterectomy.

From a statistical standpoint, either 1973 WHO or 2004/2016 WHO grading system improves the accuracy of CSM prediction to the same extent. In consequence, other considerations such as intra- and interobserver variability may represent additional metrics to consider in deciding which grading system is better.