Modern radiotherapy using image guidance for unresectable non-small cell lung cancer can improve outcomes in patients treated with chemoradiation therapy

Background: To investigate the impact of advances in image-guided radiotherapy (IGRT) on the outcomes of patients with non-small cell lung cancer (NSCLC) treated with chemoradiation therapy (CRT). Methods: We retrospectively reviewed 91 patients with NSCLC treated with definitive CRT using image guidance with daily orthogonal kilovoltage (kV) imaging compared to standard weekly megavoltage (MV) portal verifications. Kaplan-Meier curves for overall survival and locoregional failure were computed and stratified by image guidance techniques. Log-rank tests were used to compare strata. Cox Proportional Hazards models were used to identify risk factors for worse mortality and locoregional control. Results: Fifty-four percent (n=49) of patients received weekly MV portal imaging, while 46% (n=42) underwent IGRT using daily orthogonal kV imaging. kV IGRT was associated with longer median survival (36.4 months) compared to MV imaging (14.9 months; P=0.01). kV imaging was also marginally associated with lower risk of locoregional failure. Median time to local progression in patients imaged with kV was 21.4 months compared to 10.9 months (P=0.065) for those treated with MV portal imaging. Conclusions: Daily kV imaging appears to be marginally associated with better survival and disease control when compared to MV imaging. Given the small study size and the numerable factors tested, these finding require additional confirmation.