Program Information
Pulmonary Functional Imaging Biomarkers of NSCLC to Guide and Optimize Functional Lung Avoidance Radiotherapy
Khadija Sheikh1,2, Dante PI Capaldi1,2, Douglas A Hoover2,3, David A Palma2,3, Brian P Yaremko3 and Grace Parraga1,2 1Robarts Research Institute, 2Department of Medical Biophysics, 3Department of Oncology, The University of Western Ontario, London, Canada.
Presentations
WE-FG-206-8 (Wednesday, August 3, 2016) 1:45 PM - 3:45 PM Room: 206
Purpose:Functional lung avoidance radiotherapy promises optimized therapy planning by minimizing dose to well-functioning lung and maximizing dose to the rest of the lung. Patients with NSCLC commonly present with co-morbid COPD and heterogeneously distributed ventilation abnormalities stemming from emphysema, airways disease, and tumour burden. We hypothesized that pulmonary functional imaging methods may be used to optimize radiotherapy plans to avoid regions of well-functioning lung and significantly improve outcomes like quality-of-life and survival. To ascertain the utility of functional lung avoidance therapy in clinical practice, we measured COPD phenotypes in NSCLC patients enrolled in a randomized-controlled-clinical-trial prior to curative intent therapy.
Methods:Thirty stage IIIA/IIIB NSCLC patients provided written informed consent to a randomized-controlled-clinical-trial (https://clinicaltrials.gov/ct2/show/NCT02002052) comparing outcomes in patients randomized to standard or image-guided radiotherapy. Hyperpolarized noble gas MRI ventilation-defect-percent (VDP) (Kirby et al, Acad Radiol, 2012) as well as CT-emphysema measurements were determined. Patients were stratified based on quantitative imaging evidence of ventilation-defects and emphysema into two subgroups: 1) tumour-specific ventilation defects only (TSD), and, 2) tumour-specific and other ventilation defects with and without emphysema (TSDVE). Receiver-operating-characteristic (ROC) curves were used to characterize the performance of clinical measures as predictors of the presence of non-tumour specific ventilation defects.
Results:Twenty-one out of thirty subjects (70%) had non-tumour specific ventilation defects (TSDVE) and nine subjects had ONLY tumour-specific defects (TSD). Subjects in the TSDVE group had significantly greater smoking-history (p=.006) and airflow obstruction (FEV₁/FVC) (p=.001). ROC analysis demonstrated an 87% classification rate for smoking pack-years, 90% for FEV₁/FVC, and 56% for tumour RECIST measurements for identifying patients with non-tumour and tumour-specific ventilation abnormalities.
Conclusion:70% of NSCLC patients had ventilation abnormalities stemming from emphysema, airways disease and tumour burden. Smoking-history and airflow obstruction, but not RECIST, identified NSCLC patients with ventilation abnormalities appropriate for functional lung avoidance therapy.
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