Patterns of failure observed in the two-step institution credentialing process for NRG Oncology/RTOG 1005 (NCT01349322) and lessons learned.

The review of the benchmark and rapid review QA submissions indicates that acceptable variations or unacceptable deviations for the ipsilateral lung and heart dose constraints were the most commonly observed cause of benchmark QA failure, while unacceptable deviations in target contouring, rather than normal structure contouring, were the most common cause of rapid review QA failure. These findings suggest that a rigorous QA process is necessary for high quality and homogeneity in radiotherapy in multi-institutional trials of breast cancer to ensure that the benefits of radiotherapy far outweigh the risks.