Centralized Quality Assurance of Stereotactic Body Radiation Therapy for the Veterans Affairs Cooperative Studies Program Study Number 2005: A Phase 3 Randomized Trial of Lung Cancer Surgery or Stereotactic Radiotherapy for Operable Early-Stage Non-Small Cell Lung Cancer (VALOR)

Abstract

Purpose: The phase 3 Veterans Affairs Lung Cancer Surgery Or Stereotactic Radiotherapy study implemented centralized quality assurance (QA) to mitigate risks of protocol deviations. This report summarizes the quality and compliance of the first 100 participants treated with stereotactic body radiation therapy (SBRT) in this study.

Methods and materials: A centralized QA program was developed to credential and monitor study sites to ensure standard-of-care lung SBRT treatments are delivered to participants. Requirements were adapted from protocols established by the National Cancer Institute's Image and Radiation Oncology Core, which provides oversight for clinical trials sponsored by the National Cancer Institute's National Clinical Trials Network.

Results: The first 100 lung SBRT treatment plans were reviewed from April 2017 to October 2022. Tumor contours were appropriate in all submissions. Planning target volume (PTV) expansions were less than the minimum 5 mm requirement in 2% of cases. Critical organ-at-risk structures were contoured accurately for the proximal bronchial tree, trachea, esophagus, spinal cord, and brachial plexus in 75%, 92%, 100%, 100%, and 95% of cases, respectively. Prescriptions were appropriate in 98% of cases; 2 central tumors were treated using a peripheral tumor dose prescription while meeting organ-at-risk constraints. PTV V100% (the percentage of target volume that receives 100% or more of the prescription) values were above the protocol-defined minimum of 94% in all but 1 submission. The median dose maximum (Dmax) within the PTV was 125.4% (105.8%-149.0%; SD ± 8.7%), where values reference the percentage of the prescription dose. High-dose conformality (ratio of the volume of the prescription isodose to the volume of the PTV) and intermediate-dose compactness [R50% (ratio of the volume of the half prescription isodose to the volume of the PTV) and D2cm (the maximum dose beyond a 2 cm expansion of the PTV expressed as a percentage of the prescription dose)] were acceptable or deviation acceptable in 100% and 94% of cases, respectively.

Conclusions: The first 100 participants randomized to SBRT in this study were appropriately treated without safety concerns. A response to the incorrect prescriptions led to preventative measures without further recurrences. The program was developed in a health care system without prior experience with a centralized radiation therapy QA program and may serve as a reference for other institutions.