Who should be included in a clinical trial of screening for bladder cancer?

Abstract

Because of its relatively low incidence, bladder cancer screening might have a better ratio of benefits to harms if it is restricted to a high-risk population. Data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial were used and simple decision analytic techniques were applied to compare different eligibility criteria for a screening trial. For a variety of possible eligibility criteria, the percentage of the population aged 55 years to 74 years and classified as being at high risk for developing invasive or high-grade carcinoma, and therefore likely to benefit from screening, was calculated. Regression models were used to calculate a risk score based on age, sex, smoking history, and family history of bladder cancer. The reduction in cases was calculated given hypothetical risk reductions associated with screening. The trade-off between patients screened and tumors avoided was calculated as a net benefit. The 5-year probability of being diagnosed with invasive bladder cancer was 0.24%. Using a risk score > 6 or > 8 as the eligibility criterion for a trial was generally superior to including all older adults. In a typical scenario, a risk score > 6 would result in approximately 25% of the population being screened to prevent 57 invasive or high-grade bladder cancers per 100,000 population; screening the entire population would prevent only an additional 38 cases. Screening for bladder cancer can be optimized by restricting it to a subgroup of patients considered to be at elevated risk. Different eligibility criteria for a screening trial can be compared rationally using decision-analytic techniques.