The relationship between pulmonary function metrics and radiation-induced lung injury

Abstract

Introduction: Radiation-induced lung injury (RILI) is a potentially fatal yet incompletely understood complication following radiation therapy. Models have been posited to predict RILI risk but have produced inconsistent results. Here we evaluate pulmonary function testing (PFT) metrics vs. RILI incidence with the hope of establishing clinical thresholds for RILI risk. Methods: Our study population consisted of adult patients who completed conventionally-fractionated, definitive external beam RT for non-small cell lung cancer in a five-year period (January 1, 2006 to December 31, 2010). All patients were treated by a single radiation oncologist with identical technique, with dose prescriptions ranging from 50.4-74.4 Gray. We collected demographic and treatment variables, pre-radiation PFT values, and ≥ grade III RILI events. Results: There were 62 patients in our dataset. RILI occurred in 6 patients. No significant associations were seen between age, radiation dose, or the use of chemotherapy vs. the development of RILI. Tukey’s plots were constructed for PFT parameters and showed no significant differences in PFT values (absolute or percent of predicted) among RILI vs. non-RILI patients. Conclusions Our study compared pulmonary function parameters and other variables versus the development of RILI in patients treated for non-small cell lung cancer by a single radiation oncologist. We found no correlation between PFT values and risk of RILI. More research is needed to understand better the risks of RILI and to develop a clinically-useful and consistent model for RILI prediction.