Standardization of radiation therapy dose for locally advanced non-small cell lung cancer through changes to a lung cancer clinical pathway in a large, integrated comprehensive cancer center network

Purpose: The results of Radiation Therapy Oncology Group (RTOG) 0617, which randomized patients with stages IIIA/IIIB non-small cell lung cancer (NSCLC) to definitive chemoradiation therapy to 60 Gy versus 74 Gy, demonstrated a detrimental survival impact with high-dose radiation therapy. We evaluated the impact of changes to a provider-driven clinical pathway (CP) guiding management of NSCLC on practice throughout our cancer center network.

Methods and materials: In 2001, we implemented a CP for management of stage IIIA/IIIB NSCLC with definitive chemoradiation therapy. In 2013, the CP for NSCLC was amended (amendment 1) to allow a dose range of 60 to 74 Gy. The CP was amended (amendment 2) in January 2016 to specify a dose range of 60 to 70 Gy. Higher doses were considered off-pathway and subject to peer review. Data from decisions entered from 2012 to 2016 were obtained.

Results: From 2012 until publication of RTOG 0617 in February 2015, the median prescription dose was 66 Gy delivered in 1.8 to 2.1 Gy fractions. Doses ≤66 Gy were prescribed for 52% of patients. From February 2015 to September 2016, the median prescription dose was 60 Gy, and 91% of prescription doses were ≤66 Gy. After amendment 2, 99% of decisions were ≤66 Gy. Dose ≤66 Gy was associated with treatment following publication of 0617 (P < .001) and treatment after amendment 2 (P < .001). On multivariable analysis, treatment after amendment 2 was associated with dose ≤66 Gy (odds ratio, 9.9; 95% confidence interval, 5.2-19.0; P < .001). The percentage of lung receiving 20 Gy was lower following publication of 0617 (P < .001). There was no difference in the percentage of heart receiving 40 Gy.

Conclusions: CPs eliminate variations in practice 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 on the publication of RTOG 0617. We found that the CP was a tool to ensure patients receive evidence-based care across a large cancer center network.