Incidence of infiltrating cancer following superficial bladder carcinoma

Patients with histologically confirmed first diagnosis of superficial bladder carcinoma notified to the population-based cancer registry of the Swiss Canton of Vaud during the calendar period 1974-90 were actively followed-up to December 31, 1990 for the occurrence of a subsequent invasive tumour of the urinary bladder. Among 1,012 incident cases of superficial bladder neoplasms, followed for a total of 6,286 person/years at risk, 93 infiltrating tumours of the urinary bladder were diagnosed. Only 5.3 cases were expected on the basis of the general population of the canton. The overall standardized incidence ratio (SIR) was 17.5 (95% confidence interval, CI: 14.2-21.7). The SIR was significantly greater for females than for males. The SIR was highest between 1 and 4 years following registration of non-infiltrating cancer, and declined thereafter. The cumulative risk of invasive bladder cancer was 7%, 13%, and 16%, after 5, 10 and 15 years, respectively. This work provides population-based, accurate and reliable estimates of the risk of invasive bladder cancer following non-infiltrating cancers. Although the overall relative risk was almost 20-fold higher than in the general population, the cumulative risk of developing an invasive bladder cancer was only 16% at 15 years.