Analysis of primary tumor metabolic volume during chemoradiotherapy in locally advanced non-small cell lung cancer.

PURPOSE: Positron emission tomography with 2‑deoxy-2-[fluorine-18] fluoro-d-glucose integrated with computed tomography (18F-FDG-PET/CT) has an established role in the initial diagnosis and staging of lung cancer. However, a prognostic value of PET/CT during multimodality treatment has not yet been fully clarified. This study evaluated the role of primary tumor metabolic volume (PT-MV) changes on PET/CT before, during, and after chemoradiotherapy (CRT).

METHODS: A total of 65 patients with non-small-cell lung cancer (NSCLC) UICC stage IIIA/B (TNM 7th Edition) were treated with definitive chemoradiotherapy (sequential or concurrent setting). PET/CT was acquired before the start, at the end of the third week, and 6 weeks following CRT.

RESULTS: Median overall survival (OS) for the entire cohort was 16 months (95% confidence interval [CI]: 12-20). In all, 60 (92.3%) patients were eligible for pre-treatment (pre-PT-MV), 28 (43%) for mid-treatment (mid-PT-MV), and 53 (81.5%) for post-treatment (post-PT-MV) volume analysis. Patients with pre-PT-MV >63 cm3 had worse OS (p < 0.0001). A reduction from mid-PT-MV to post-PT-MV of >15% improved OS (p = 0.001). In addition, patients with post-PT-MV > 25 cm3 had significantly worse outcome (p = 0.001). On multivariate analysis, performance status (p = 0.002, hazard ratio [HR] 0.007; 95% CI 0.00-0.158), pre-PT-MV1 < 63 cm3 (p = 0.027, HR 3.98; 95% CI 1.17-13.49), post-PT-MV < 25 cm3 (p = 0.013, HR 11.90; 95% CI 1.70-83.27), and a reduction from mid-PT-MV to post-PT-MV > 15% (p = 0.004, HR 0.25; 95% CI 0.02-0.31) correlated with improved OS.

CONCLUSIONS: Our results demonstrated that pre- and post-treatment PT-MV, as well as an at least 15% reduction in mid- to post-PT-MV, significantly correlates with OS in patients with inoperable locally advanced NSCLC.