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

Abstract Purpose To investigate patterns of failure in institutional credentialing submissions to XXX/YYYY XXXX with the aim of improving the quality and consistency for future breast cancer protocols. Materials/Methods XXX/YYYY XXXX allowed the submission of 3DCRT, IMRT and simultaneous integrated boost (SIB) breast plans. Credentialing required institutions to pass a two-step quality assurance (QA) process: (1) benchmark, requiring institutions to create a plan with no unacceptable deviations and ≤ one acceptable variation among the dose volume (DV) criteria, and (2) rapid review, requiring each institution’s first protocol submission to have no unacceptable deviations among the DV criteria or contours. Overall rates, number of resubmissions and reasons for resubmission were analyzed for each QA step. Results In total, 352 institutions participated in benchmark QA and 280 patients enrolled had rapid review QA. Benchmark initial failure rates were similar for 3DCRT (18%), IMRT (17%) and SIB (18%) plans. For 3DCRT and IMRT benchmark plans, ipsilateral lung most frequently failed the DV criteria, while SIB DV failures were seen most frequently for the heart. Rapid review contour initial failures (35%) were due to target rather than organs at risk. For 29% of the rapid review initial failures, the PTV boost eval volume was deemed an unacceptable deviation. Conclusions 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.