Improved long-term outcome of patients with non-muscle invasive, low and intermediate risk bladder cancer between 1997 and 2014; a Swedish population-based study

Objective The most common form of urinary bladder cancer is the low and intermediate risk categories of stage Ta. This patient group has a high recurrence rate, but progression is rare. The aim of this study was to investigate recurrence and survival in a large population-based setting, with respect to possible prognostic factors and during different time periods. Patients and methods BladderBaSe is a database which links information from the Swedish National Register of Urinary Bladder Cancer with national healthcare and demographic registers. Between 1997 and 2014, 16,599 were diagnosed with low and intermediate risk of Ta cancer in Sweden. The times to recurrence and cancer-specific death were analysed concerning the differences in age, gender, grade, region and hospital type. For temporal analysis, we divided the material into 6-year periods. Results The mean age was 70 years and 75% were males. Low risk according to grade constituted 56%, whilst 44% had intermediate risk. With a median follow-up time of 63 months the recurrence rates were 47% and 59% for the respective categories and overall 52%. The rate was similar between the first two time periods, but became substantially lower in the most recent period. Five percent of patients died of the disease and risk category was the main prognostic variable. Conclusions The risk of recurrence decreased in the last time period. Risk category based on grade was the most important prognostic indicator for outcome.