Lessons from a population-based bladder cancer registry: exploring why survival is not improving

Abstract

Objective: To explore the causes of the decrease in bladder cancer survival that has occurred over the past four decades.

Methods: We extracted data from the South Australian Cancer Registry. Data from the period 1 January 1977 to 31 December 2020 were extracted to explore changes in incidence and survival among a total of 8356 patients diagnosed with ≥pT1 disease. Invasive bladder cancer was defined as ≥pT1 in this study.

Results: Invasive bladder cancer age-standardized incidence decreased from 7.20 cases per 100 000 people in 1977 to 5.85 cases per 100 000 in 2020. The mean age at diagnosis increased from 68 years to 76 years. The crude incidence for patients aged 80 years and over increased by 3.3% per year (95% confidence interval [CI] 2.1 to 4.6). Overall survival decreased over the study period (hazard ratio [HR] 1.22 [95% CI 1.09 to 1.35]), however, survival increased after adjusting for age at diagnosis (HR 0.80 [95% CI 0.76 to 0.94]). Despite a decrease in non-bladder cancer-specific deaths in older people, there was no change in the bladder cancer-specific death rate in older people (HR 0.94 [95% CI 0.70 to 1.26]). Male sex was associated with higher survival (HR 0.87 [95% CI 0.83 to 0.92]), whereas socioeconomic advantage was not.

Conclusions: Invasive bladder cancer survival has decreased over the past 40 years, with the age structure of the population being a significant contributing factor.

Patient summary: We looked at why bladder cancer survival is decreasing using a large cancer registry with information from 1977 to 2020. We found that people are now more likely to be diagnosed at an older age. Older people often live for a shorter time with bladder cancer compared to younger people. Bladder cancer survival has decreased because there are more older people with the disease than previously.

Keywords: bladder cancer; elderly; older people; survival; urology.