An Update of the Credentialing Process for the NRG Oncology NSABP B-51 / RTOG 1304 Phase 3 Randomized Clinical Trial

Purpose/Objective(s): NSABP B‐51/RTOG 1304 is a randomized phase 3 clinical trial evaluating regional nodal (RN) radiation therapy (RT) in patients (pts) with positive axillary nodes before neoadjuvant chemotherapy (NC) who convert to negative axillary nodes (ypN0) after NC. After lumpectomy, pts are randomized to whole breast RT (Arm 1A) versus breast and RN RT (Arm 2A), and post‐mastectomy pts are randomized to observation (Arm 1B) versus chest wall and RN RT (Arm 2B). This is the first multi‐institution group trial evaluating breast cancer RN RT, requiring 3DCRT or IMRT treatment plans based on CT contouring with DVH plan evaluation. Institutions must be credentialed to demonstrate that physics staff has read the protocol, meet specific technology requirements, and generate RT plans meeting protocol‐defined RT dose volume constraints. The credentialing goal is to reduce protocol deviations and provide institutional feedback to correct unacceptable variations before pt enrollment. Materials/Methods: Credentialing includes completing a Facility Questionnaire and developing 3DCRT and/or IMRT treatment plan for 3 CT benchmark cases for: Arm 1A: breast RT only; 2A: breast and RN RT; and 2B: post‐mastectomy chest wall and RN RT downloaded from the IROC Houston's website. RN RT includes dose coverage of supraclavicular, axillary, and internal mammary nodes in the first 3 intercostal spaces. IROC Houston reviews the benchmarks using MIM to verify that the dose to targets and constraints to organs at risk meet protocol‐specified criteria. Credentialed intuitions may then enroll pts. The first case enrolled on Arms 2A and 2B undergo pre‐treatment review and are scored per protocol: variation acceptable or variation unacceptable. Results: NSABP B‐51/ RTOG 1304 opened 8‐22‐2013 with a targeted accrual of 1601. Three hundred nine institutions have initiated the credentialing process. 252 that have submitted benchmarks for review with 2% failed and never resubmitted. Credentialed techniques are 7% IMRT only, 48% 3DCRT only, and 45% 3DCRT and IMRT. Benchmark initial failure rates requiring re‐submission are: 25% failed the benchmark for breast RT only (1A); 12% failed 2B post‐mastectomy chest wall and RN RT; 39% failed 2A breast and RN RT at least once before being credentialed. 9% of the institutions failed 2A twice and 1 failed three times. 296 are credentialed to enter pts. 48 enrolled cases have had pre‐treatment reviews and 14 scored "unacceptable" with re‐submission for re‐review due to target volume contouring. Conclusion: NSABP B‐51/ RTOG 1304 credentialing prepares institutions for RT delivery to meet protocol requirements. This revealed Arm 2A, breast RT, and RN RT still requires resubmission for most institutions to meet protocol guidelines.