Imaging-Based Target Volume Reduction May Improve Local Control in NSCLC

According to findings from a multi-center study, ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET-based planning may improve local control without increasing toxicity in patients with locally advanced non–small-cell lung cancer (NSCLC; Lancet Oncol. 2020 Apr;21[4]:581-592).

“With increasingly precise radiotherapy and advanced medical imaging, the concept of radiotherapy target volume planning might be redefined with the aim of improving outcomes,” explained Ursula Nestle, MD, Department of Radiation Oncology, Kliniken Maria Hilf, Germany, and colleagues, who sought to evaluate the feasibility and efficacy of target volume reduction versus conventional planning in the context of radical chemoradiotherapy for patients with locally advanced NSCLC.

Between May 13, 2009, and December 5, 2016, a total of 205 untreated patients were enrolled in the controlled, open-label study from 24 centers across Austria, Germany, and Switzerland. Patients had previously untreated, inoperable disease suitable for chemoradiotherapy and underwent ¹⁸F-FDG PET and CT for treatment planning before being randomized in a 1:1 ratio

to the conventional target arm (n = 99) or the ¹⁸F-FDG PET-based target arm (n = 106; the intention-to-treat set).

The primary end point of the study was time to locoregional progression from point of randomization with the objective of testing the noninferiority of ¹⁸F-FDG PET-based planning with a prespecified hazard ratio (HR) margin of 1.25.

Overall, 172 patients were treated per protocol (84 in the conventional target arm and 88 in the ¹⁸F-FDG PET-based target arm).

As of a median follow-up time frame of 29 months, the risk for locoregional progression in the ¹⁸F-FDG PET-based target arm was noninferior to (and lower than) that of the conventional target arm in the per-protocol set (14%; 95% CI, 5-21 vs 29%; 95% CI, 17-38 at 1 year; HR, 0.57; 95% CI, 0.30-1.06).

The ¹⁸F-FDG PET-based target arm also had a noninferior risk for locoregional progression compared with the conventional target arm in the intention-to-treat set (17%; 95% CI, 9-24 vs 30%; 95% CI, 20-39 at 1 year; HR, 0.64; 95% CI, 0.37-1.10).

The most frequently reported acute grade ≥3 adverse events were esophagitis or dysphagia (16% in the conventional target arm vs 16% in the ¹⁸F-FDG PET-based target arm); the most common late toxicities were lung-related (12% vs 10%, respectively); and there were 20 deaths potentially related to the study therapy (7 vs 13, respectively).

“¹⁸F-FDG PET-based planning could potentially improve local control and does not seem to increase toxicity in patients with chemoradiotherapy-treated locally advanced non-small-cell lung cancer. Imaging-based target volume reduction in this setting is, therefore, feasible, and could potentially be considered standard of care,” Dr Nestle and co-investigators concluded.

“The procedures established might also support imaging-based target volume reduction concepts for other tumours,” they added.—Hina Porcelli