Appropriate endpoints for superficial bladder cancer clinical trials.

Many protocols for treatment of superficial bladder cancer include periodic cystoscopic examinations with resection of visible lesions. This allows pathological restaging of the disease at each examination. For example, this type of follow-up is common in clinical trials evaluating intravesical therapies. In such trials, clinical outcome is typically summarized using end-points that measure failure to control superficial disease. Alternative endpoints measuring failure to prevent progression to invasive disease are often ignored. In this report, the rationale for ignoring the invasive disease endpoints is given and flaws in the rationale are described. Evidence from actual data sets support the view that superficial disease endpoints may not be appropriate surrogates for invasive disease endpoints. It is recommended that time to invasive disease should be considered a major endpoint when designing and analyzing trials in superficial bladder cancer.