Tina Marie Briere1, Shane Krafft2, Zhongxing Liao3, Mary K Martel2. 1. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas. Electronic address: tmbriere@mdanderson.org. 2. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas. 3. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
Abstract
PURPOSE: The purpose of this study was to identify patient populations treated for non-small cell lung cancer (NSCLC) who may be more at risk of radiation pneumonitis. METHODS AND MATERIALS: A total of 579 patients receiving fractionated 3D conformal or intensity modulated radiation therapy (IMRT) for NSCLC were included in the study. Statistical analysis was performed to search for cohorts of patients with higher incidences of radiation pneumonitis. In addition to conventional risk factors, total and spared lung volumes were analyzed. The Lyman-Kutcher-Burman (LKB) and cure models were then used to fit the incidence of radiation pneumonitis as a function of lung dose and other factors. RESULTS: Total lung volumes with a sparing of less than 1854 cc at 40 Gy were associated with a significantly higher incidence of radiation pneumonitis at 6 months (38% vs 12% for patients with larger volumes, P<.001). This patient cohort was overwhelmingly female and represented 22% of the total female population of patients and nearly 30% of the cases of radiation pneumonitis. An LKB fit to normal tissue complication probability (NTCP) including volume as a dose modifying factor resulted in a dose that results in a 50% probability of complication for the smaller spared volume cohort that was 9 Gy lower than the fit to all mean lung dose data and improved the ability to predict radiation pneumonitis (P<.001). Using an effective dose parameter of n=0.42 instead of mean lung dose further improved the LKB fit. Fits to the data using the cure model produced similar results. CONCLUSIONS: Spared lung volume should be considered when treating NSCLC patients. Separate dose constraints based on smaller spared lung volume should be considered. Smaller spared lung volume patients should be followed closely for signs of radiation pneumonitis.
PURPOSE: The purpose of this study was to identify patient populations treated for non-small cell lung cancer (NSCLC) who may be more at risk of radiation pneumonitis. METHODS AND MATERIALS: A total of 579 patients receiving fractionated 3D conformal or intensity modulated radiation therapy (IMRT) for NSCLC were included in the study. Statistical analysis was performed to search for cohorts of patients with higher incidences of radiation pneumonitis. In addition to conventional risk factors, total and spared lung volumes were analyzed. The Lyman-Kutcher-Burman (LKB) and cure models were then used to fit the incidence of radiation pneumonitis as a function of lung dose and other factors. RESULTS: Total lung volumes with a sparing of less than 1854 cc at 40 Gy were associated with a significantly higher incidence of radiation pneumonitis at 6 months (38% vs 12% for patients with larger volumes, P<.001). This patient cohort was overwhelmingly female and represented 22% of the total female population of patients and nearly 30% of the cases of radiation pneumonitis. An LKB fit to normal tissue complication probability (NTCP) including volume as a dose modifying factor resulted in a dose that results in a 50% probability of complication for the smaller spared volume cohort that was 9 Gy lower than the fit to all mean lung dose data and improved the ability to predict radiation pneumonitis (P<.001). Using an effective dose parameter of n=0.42 instead of mean lung dose further improved the LKB fit. Fits to the data using the cure model produced similar results. CONCLUSIONS: Spared lung volume should be considered when treating NSCLCpatients. Separate dose constraints based on smaller spared lung volume should be considered. Smaller spared lung volume patients should be followed closely for signs of radiation pneumonitis.
Authors: Yevgeniy Vinogradskiy; Chad G Rusthoven; Leah Schubert; Bernard Jones; Austin Faught; Richard Castillo; Edward Castillo; Laurie E Gaspar; Jennifer Kwak; Timothy Waxweiler; Michele Dougherty; Dexiang Gao; Craig Stevens; Moyed Miften; Brian Kavanagh; Thomas Guerrero; Inga Grills Journal: Int J Radiat Oncol Biol Phys Date: 2018-10-18 Impact factor: 7.038
Authors: Mohammed Alharbi; Stefan Janssen; Heiko Golpon; Michael Bremer; Christoph Henkenberens Journal: Radiat Oncol Date: 2017-11-02 Impact factor: 3.481