Image guided brachytherapy quality assurance on NRG GY017 investigating immunotherapy in addition to chemoradiation for locally advanced cervical cancer.

INTRODUCTION

Brachytherapy is a critical component of curative treatment in locally advanced cervical cancer. NRG GY-017 is a randomized Phase I trial of the anti-PD-L1 antibody atezolizumab administered neoadjuvantly and concurrently with chemoradiation (Arm A) or only concurrently with chemoradiation (Arm B) in patients with node positive locally advanced cervical cancer. Image guided brachytherapy (IGBT) was mandated in the protocol with a quality assurance (QA) workflow. Herein, we report the BT quality data on NRG GY-017 trial and practice patterns from the participating centers in this trial as a guide for future protocol brachytherapy QA.

METHODS

The participating sites were to submit brachytherapy plans online after BT was completed. IROC QA center compiled the BT fractions for each patient using the trial specific dosimetry evaluation template. An expert physician reviewer scored the contours and plans as per protocol, variation acceptable or major deviation as prespecified in the protocol dose metrics.

RESULTS

The BT dosimetry results were available for 32 patients. Seventeen patients (53%) had intracavitary applicator, and 15 patients (47%) had hybrid or interstitial applicators. Point A directed planning was performed for 4 patients (12.5%) and 28 patients had volume directed plans (87.5%). For imaging use, 2 patients had MRI based plans, and 30 had CT based planning (94%). For the dose constraints compliance per protocol, 7 patients had 9 events scored as major deviations (22%).

CONCLUSION

BT trial specific QA has the potential to enhance BT quality for clinical trials. This report will help guide future gynecologic BT trial data collection and QA process.