Feasibility of Omitting Clinical Target Volume under PET-CT Guidance in Unresectable Stage III Non-Small-Cell Lung Cancer, a Phase II Clinical Trial

Abstract

<h3>Purpose/Objective(s)</h3> This clinical trial aims to investigate the feasibility of CTV-omitted, positron-emission tomography computed tomography (PET-CT) combined with intensity-modulated radiation therapy (IMRT) for unresectable stage III NSCLC. <h3>Materials/Methods</h3> This was a single-center, phase II clinical trial initiated in July 2016. Patients with unresectable stage III NSCLC undergoing routine IMRT were randomly enrolled into the study group (CTV-omitted under PET-CT guidance) and the control group (CTV-delineated). The primary endpoint was the incidence of radiation respiratory events or esophagitis with grade 3 or higher. The secondary endpoints included objective response rate (ORR), locate control rate, progression-free survival (PFS), failure pattern and overall survival (OS). <h3>Results</h3> A total of 62 patients were enrolled between July 2016 and October 2018. The incidence of radiation respiratory events or esophagitis with grade 3 or higher was 6.5 % in the study group, significantly lower than the rate of 25.8 % in the control group (P = 0.04), basically due to the reduced irradiated volumes of the lungs and esophagus in the study group. The median PFS was 11.0 months versus 9.0 months (P = 0.374), and the median OS 31.0 months versus 24.0 months (P = 0.186) in the study group and the control group, respectively. The failure pattern was not significantly different between the two groups (P = 0.464). <h3>Conclusion</h3> Omitting the CTV under PET-CT guidance has high feasibility to reduce severe radiation associated toxicity in IMRT for unresectable stage III NSCLC, without compromising the efficacy.