Recurrence and progression in low grade papillary urothelial tumors

Purpose: We report long-term followup data on patients with World Health Or ganization (WHO) grade I bladder tumors, and determine whether histopatholo gical subgrouping as papillary neoplasm of low malignant potential and low grade papillary carcinoma is of clinical value. Materials and Methods: All 680 patients in western Sweden with first diagno sis of bladder carcinoma in 1987 to 1988 were registered and followed for a t least 5 years. Of the tumors 255 (37.5%) were stage Ta, WHO grade I. Tumo rs were further classified as papillary neoplasm of low malignant potential in 95 patients and low grade papillary carcinoma in 160 according to WHO a nd the International Society of Urological Pathology consensus classificati on of urothelial (transitional cell) neoplasms of the bladder. Results: Mean age of patients at first diagnosis of low grade papillary car cinoma was 69.2 years, which was 4.6 years higher than those with papillary neoplasm of low malignant potential (p <0.005). During a mean observation time of 60 months our 255 patients underwent 577 operations for recurrences and had 1,858 negative cystoscopies. The risk of recurrence was significan tly lower in patients with papillary neoplasm of low malignant potential co mpared to those with low grade papillary carcinoma (35 versus 71%, p <0.001 ). The risk of recurrence was higher in patients with multiple tumors at fi rst diagnosis as well as those with recurrence at the first followup after 3 to 4 months. Stage progressed in 6 patients (2.4%), all with low grade pa pillary carcinoma at diagnosis. Conclusions: More than 90% of patients with stage Ta, WHO grade I have a be nign form of bladder neoplasm, and few have truly malignant tumors. Future research should focus on reducing the number of recurrences and followup cy stoscopies, and finding methods to identify malignant tumors so that pertin ent treatment can be instituted. Subgrouping of WHO grade I bladder tumors as papillary neoplasm of low malignant potential and low grade papillary ca rcinoma seems to add valuable prognostic information.