Standardization of Radiation Therapy Dose for Locally-Advanced Non-Small Cell Lung Cancer (NSCLC) through Changes to a Lung Cancer Clinical Pathway in Large Network

Abstract

Purpose/Objective(s): The initial results of RTOG 0617 which randomized patients with Stages IIIA/IIIB NSCLC to definitive chemoradiotherapy (CRT) to a maximum dose of 60 Gy vs. 74 Gy suggested no benefit to the high-dose arm. Final results demonstrated a detrimental survival impact with high-dose RT. Clinical pathways (CP) standardize care when many therapeutic options exist and clinical practice varies unnecessarily. We evaluated the impact of changes to a CP guiding management of NSCLC on practice patterns throughout a large, integrated comprehensive cancer center network. Purpose/Objective(s): In 2003, we implemented a CP for management of Stage IIIA/IIIB NSCLC with definitive CRT. In 2009, we required entry of treatment decisions into an online clinical physician decision support tool integrated with medical records to track CP choices. Off-pathway selections were subject to peer review. In June 2013, the CP for NSCLC was amended (amendment 1) to allow a dose range of 60-74 Gy with heterogeneity correction, reflecting the two arms of 0617. The CP was again changed (amendment 2) in January 2016 to specify a dose range of 60-70 Gy, and higher doses were considered off-pathway and subject to peer review. Data from treatment decisions entered from January 2012 to September 2016 were obtained. Result(s): From 2012 until final publication of 0617 in February 2015, 367 treatment decisions were entered. The median prescription dose was 66 Gy (range, 54.0-79.8) delivered in 1.8-2.1 Gy fractions. Doses <66 Gy were prescribed for 190 patients (52%). From February 2015 to September 2016, 211 treatment decisions were entered. The median prescription RT dose was 60 Gy (range, 60-76). Prior to amendment 2, 117 (91%) of 128 prescription doses were <66 Gy. After amendment 2, 82 (99%) of 83 decisions were <66 Gy. Stage of disease was not associated with dose <66 Gy (p=0.984). Dose <66 Gy was associated with treatment following publication of 0617 (p<0.001) and treatment after amendment 2 (p<0.001), though on multivariate analysis, only treatment after amendment 2 was associated with dose <66 Gy (OR 9.9, 95% CI 5.2-19.0, P<0.001). The overall median heart V40 Gy and lung V20 Gy were 4.3% (range 0-36.0) and 25.7% (range 4.1-44.5), respectively. Lung V20 Gy was lower following publication of 0617 (median 23.4%) than before (median 28.8%) (p<0.001), but there was no difference in heart V40 Gy (p=0.70). Conclusion(s): CP's translate published research and institutional experience into standardized patient management plans to promote evidence-based care and eliminate inefficient variations in practice patterns that lead to inferior outcomes. Recognizing that our CP for definitive treatment of patients with locally-advanced NSCLC allowed heterogeneous dose prescriptions, we modified the CP based upon the final publication of RTOG 0617. We found that the CP was a powerful tool to ensure patients receive consistent high-quality, evidence-based care.