Prognostic Significance of Standardized Uptake Value of PET Scan in Non-Small Cell Lung Cancer

Abstract

Background: To determine if the maximum standardized uptake value (SUVmax) of the primary tumor as determined by preoperative (18)F-fluoro-2-deoxyglucose ((18)F-FDG) positron emission tomography (PET) is an independent predictor of overall survival, mediastinal lymph node metastasis, and stage in patients with non-small cell lung cancer (NSCLC). Methods: A retrospective review of 1033 patients with stage I-IV histologically proven NSCLC who had an (18)F-FDG PET done between 2005 and 2011 for staging before receiving therapy was performed. SUVmax of primary NSCLC was measured and correlated with tumor characteristics, lymph node involvement, cancer stage and overall survival. The patients were divided into three groups according to their SUVmax value: group I SUVmax < 5; group II SUVmax 5 - 10; and group III SUVmax > 10. The primary outcome was survival and recurrence rate, compared using Log Rank Test. Results: The median duration of follow up was 675 days (22.5 months). The overall survival at two years for group I was 88%, group II 60% and group III 53%, significantly different among the three groups (p-value < 0.0001). Earlier stage lung cancer was found in patients with lower SUVmax values: in group I, 73% of patients had stage I cancer and only 4% had stage IV. The rate of ipsilateral mediastinal lymph node involvement (N2) in group I was 12.9% compared to 44.4% in group III (p-value < 0.0001). The overall survival was significantly different between group I and group II (Hazard Ratio (HR) 3.6; 95% C.I 2.2 - 5.7 and a p-value < 0.0001) and between group II and group III (HR 1, 4; 1.1 - 1.8 and a p-value = 0.013). Conclusion: There was a statistically significant difference in the overall survival, mediastinal lymph node metastases, and higher cancer stage with greater values of SUVmax on PET scan in patients with NSCLC.