Early Prediction of Response to First-Line Therapy Using Integrated 18F-FDG PET/CT for Patients with Advanced/Metastatic Non-small Cell Lung Cancer

Introduction: Early prediction of treatment response is of great value to avoid unnecessary toxicity of ineffective treatment and to get a chance to receive another effective treatment earlier. We conducted a prospective study to evaluate the role of integrated 18-fluorodeoxyglucose positron emission tomography/computed tomography as a tool for early response predictor. Methods: Between May 2004 and November 2005, 31 patients with pathologically proven stage IIIB/IV non-small cell lung cancer participated in this study. Metabolic response was assessed prospectively after one cycle of systemic therapy, which was compared with conventional radiographic response according to the World Health Organization criteria. Results: By the World Health Organization criteria, 10 of 31 patients (32.3%) achieved a partial response, 7 stable diseases, and 14 progressive diseases, whereas there were 7 partial metabolic responses, 13 stable metabolic diseases, and 11 progressive metabolic diseases. Out of 7 partial metabolic responses, 5 achieved partial response, 1 stable disease, and 1 progressive disease (positive predictive value of 71.4% [5 of 7]), whereas 9 of the 11 progressive metabolic diseases had progressive diseases and the other 2 showed stable diseases (negative predictive value of 100% [11 of 11]). There were moderate correlation between early metabolic response and best overall response (Spearman r = 0.62, p < 0.01). However, an early metabolic response did not translate into better survival outcome. Conclusions: Single 18-fluorodeoxyglucose positron emission tomography/computed tomography scan taken after one cycle of treatment could predict progressive disease earlier than standard radiographic evaluation and call be used as a measure to avoid ineffective systemic chemotherapy.