Introduction: The aim of the study was to investigate repetitive fractional exhaled nitric oxide (FeNO) measurements during high-dose radiation therapy (HDRT) and to evaluate the use of FeNO to predict symptomatic radiation pneumonitis (RP) in patients being treated for non-small cell lung cancer (NSCLC).
Materials and methods: A total of 50 patients with NSCLC referred for HDRT were enrolled. FeNO was measured at baseline, weekly during HDRT, one month- and every third month after HDRT for a one-year follow-up period. The mean FeNO(visit 0-6) was calculated using the arithmetic mean of the baseline and weekly measurements during HDRT. Patients with grade???2 of RP according to the Common Terminology Criteria for Adverse Events (CTCAE) were considered symptomatic.
Results: A total of 42 patients completed HDRT and weekly FeNO measurements. Grade???2 of RP was diagnosed in 24 (57%) patients. The mean FeNO(visit 0-6)?�?standard deviation in patients with and without RP was 15.0?�?7.1?ppb (95%CI: 12.0-18.0) and 10.3?�?3.4?ppb (95%CI: 8.6-11.9) respectively with significant differences between the groups (p?=?0.0169, 95%CI: 2.3-2.6). The leave-one-out cross-validated cut-off value of the mean FeNO(visit 0-6)???14.8?ppb was predictive of grade???2 RP with a specificity of 71% and a positive predictive value of 78%.
Conclusions: The mean FeNO(visit 0-6) in patients with symptomatic RP after HDRT for NSCLC was significantly higher than in patients without RP and may serve as a potential biomarker for RP.