Noninvasive inverted urothelial papillary tumour tied to low recurrence, better outcomes

Noninvasive urothelial papillary lesions of the bladder with an inverted growth pattern appear to have a low chance of recurrence and are associated with better outcomes, suggests a study.

The investigators observed lower recurrence rates for inverted papillary urothelial neoplasm of low malignant potential (IPUNLMP) than for papillary urothelial neoplasms of low malignant potential, as well as for low-grade papillary urothelial carcinoma with an inverted growth pattern (LG-PUCI) than for low-grade papillary urothelial carcinomas. No recurrence arose in inverted urothelial papilloma cases.

The corresponding 2- and 5-year disease-free survival rates were 100.0 percent and 85.2 percent for patients with IPUNLMP; 94.4 percent and 80.4 percent for those with papillary urothelial neoplasms of low malignant potential; 89.5 percent and 82.0 percent for LG-PUCI patients; 73.7 percent and 54.6 percent for those with low-grade papillary urothelial carcinoma; 40.0 percent and 20.0 percent for patients with high-grade papillary urothelial carcinoma with an inverted growth pattern; and 26.7 percent and 26.7 percent for those with high-grade papillary urothelial carcinoma.

In multivariate analysis, tumour number strongly predicted disease-free survival in patients with IPUNLMP and with LG-PUCI/high-grade papillary urothelial carcinoma with an inverted growth pattern.

In this study, the investigators collected archived paraffin-embedded urothelial tumour samples from patients diagnosed with inverted urothelial papillary lesions between January 2005 and June 2020. They then selected a matched control population of patients with exophytic papillary lesions of the urothelium diagnosed during the same period.

Finally, the investigators examined the conventional clinicopathological features of inverted urothelial papillary tumour and recorded patient demographics, tumour characteristics, recurrence, and survival information.