(18)F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Interpretation Criteria for the Assessment of Therapeutic Response in Patients with Advanced Stage of Lung Cancer: Inter-Reader Reliability, Accuracy, and Survival Outcomes

AIM: (18)F-fluorodeoxyglucose positron emission tomography-computed tomography ((18)F-FDG-PET/CT) is useful in the evaluation of lung cancer (LC), both for staging and therapy assessment. However, for the evaluation of treatment response, shared criteria are not available. We proposed a 3-point score, similar to Deauville-score and compared its diagnostic accuracy with Hopkins criteria for the evaluation of treatment response in LC to validate a qualitative and simpler interpretation system. METHODS: We retrospectively included 93 patients with advanced stage (III-IV) LC who underwent (18)F-FDG-PET/CT after first-line treatment. Positron emission tomography/computed tomography (PET/CT) scans were interpreted according to a 3-point scale-like Deauville score criteria (score 1 = uptake lower than blood-pool activity; score 2 = uptake higher than blood-pool but lower than liver activity; score 3 = uptake higher than liver). Inter-reader variability was assessed using percent agreement and kappa statistics. Kaplan–Meier plots with a Mantel-Cox log-rank test were performed, considering death as the endpoint. RESULTS: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of like Deauville-like score criteria were 82,76% (95% confidence interval [CI] 70.5%–91.4%), 80% (95% CI 28.3%–99%), 97.9% (95% CI 89.2%–99.6%), 28.6%(95% CI 16.38%–44.9%), and 82.5% (95% CI 70.9–90.9%), respectively. Applying Hopkins criteria score we obtained sensitivity, specificity, PPV, NPV, and accuracy of 81% [95% CI 68.6%–90.1%), 100% (95% CI 47.2–100%), 100% (95% CI %), 31.3% (95% CI 21.0%–43%), and 82.5%(95% CI 70.9%–90.9%), respectively. There was a high agreement between the two readers both using Hopkins criteria (k = 0.912) and like-Deauville-score criteria (k = 0.956). Applying 3-point-scale criteria, patients with positive PET/CT after therapy had significantly shorter lower survival (P = 0.0021). CONCLUSION: The application of 3-point scale criteria for posttherapy assessment in patients with advanced stage of LC represents an easy and reproducible method with optimal inter-observer agreement and great PPV and accuracy.