Validating a Local Failure Risk Stratification for Use in Prospective Studies of Adjuvant Radiation for Bladder Cancer

To inform trials of adjuvant radiotherapy for bladder cancer, a local-regional failure (LF) risk stratification was developed. We assessed the impact of multiple potential biases on the model’s validity for predicting outcomes. The predictions were not invalidated by time bias from evolving surgical techniques, use of different statistical methods to estimate LF risk, subgrouping bias due to differing definitions for the LF subgroups, or trial accrual bias from including patients ineligible for adjuvant RT trials.