The Impact of Radiotherapy Protocol Adherence on the Treatment Outcome in Patients With Locally Advanced NSCLC Treated With Concurrent Chemoradiation: Results From the Radiotherapy Quality Assurance of the International Randomized PET-Plan Trial

Abstract

Purpose/Objective(s): Cardiac radiation exposure is associated with an increased rate of adverse cardiac events in patients receiving radiation therapy for locally advanced non-small cell lung carcinoma (NSCLC). Previous analysis of practice patterns within the statewide Michigan Radiation Oncology Quality Consortium (MROQC) revealed 1 in 4 patients received a mean heart dose > 20 Gy and significant heterogeneity existed among treatment centers in using cardiac dose constraints. The purpose of this study is to analyze the effect of education and initiation of standardized cardiac dose constraints on heart dose across a statewide consortium. Materials/Methods: From 2012 to 2020, 1604 patients from 27 academic and community centers who received radiation therapy for locally advanced NSCLC were included in this analysis. Dosimetric endpoints including mean heart dose (MHD), mean lung dose, and mean esophagus dose were calculated using data from dose-volume histograms. These dose metrics were grouped by year of treatment initiation for all patients. Education regarding data for cardiac dose constraints was discussed in small lung cancer working group meetings and consortium-wide starting in 2016. This was followed in 2018 by implementation of a quality metric requiring mean heart dose < 20 Gy while maintaining dose coverage (D95) to the tumor. Dose metrics were compared before (2012-2016) and after (2017-2019) initiation of interventions targeting cardiac constraints. Statistical analysis was performed using the Wilcoxon Rank Sum test. Results: Following education and implementation of the heart dose performance metric, mean MHD declined from an average of 12.2 Gy pre-intervention to 10.4 Gy post-intervention, and the percentage of patients receiving MHD > 20 Gy reduced by half. (Table ). Mean lung dose and mean esophagus dose did not increase, and tumor coverage remained unchanged. Conclusion: Education and implementation of a standardized cardiac dose quality measure across a statewide consortium was associated with a reduction of mean heart dose in patients receiving radiation therapy for locally advanced NSCLC. These dose reductions were achieved without sacrificing tumor coverage, increasing mean lung dose or mean esophagus dose. Analysis of the clinical ramifications of the reduction in cardiac doses is ongoing.

Association between radiotherapy protocol variations and outcome in the CONVERT trial

“…CHART, GFPC-IFCT 02.01, PET-Plan, and PROCLAIM have formally reported radiotherapy QA [6] , [7] , [8] , [9] . The QA parameters differ between these clinical trials and are reported as isolated components.…”

“…This study reporting radiotherapy QA for the international randomised controlled CONVERT trial reports radiotherapy QA parameters and relates the dosimetric impact of contour variation, with treatment delivery compliance against patient outcome [6] , [7] , [10] , [12] .…”

“…Radiotherapy QA within the PROCLAIM and PET-Plan studies mandated a prospective review of the first radiotherapy plan from each centre followed by mandatory and selective on-trial review; all remaining data were reviewed retrospectively [6] , [7] . PROCLAIM QA was based on 4 trial-specific QA parameters: PTV coverage, hot spots within and outside the PTV, spinal cord dose, and V20Gy lung.…”

“…7.2% (40/554) of cases within PROCLAIM had major radiotherapy QA violations [6] . PET-Plan employed extensive radiotherapy QA (EORTC-radiotherapy QA level 4) and reported an overall 25% minor, 59% intermediate, and 15% major deviation incidence [7] . Twenty-six of the 204 evaluated radiotherapy records had more than one major deviation.…”

“…The quality of radiotherapy delivered directly impacts patient outcomes [5] . The QA parameters for radical lung radiotherapy are described; to date, CHART, GFPC-IFCT 02.01, PET-Plan, and PROCLAIM have formally reported radiotherapy QA in the radical treatment of lung cancer [6] , [7] , [8] , [9] . The radiotherapy QA parameters differ between these clinical trials with a variable focus on TV and OAR delineation, dosimetry, and treatment delivery; the radiotherapy QA parameters are reported as isolated components.…”