FDG PET-CT in Non-small Cell Lung Cancer: Relationship between Primary Tumor FDG Uptake and Extensional or Metastatic Potential

Objective: To explore the relationships between primary tumor 18F-FDG uptake measured as the SUVmaxand local extension, and nodal or distant organ metastasis in patients with NSCLC on pretreatment PET-CT.
Methods: 93 patients with NSCLC who underwent 18F-FDG PET-CT scans before the treatment were included inthe study. Primary tumor SUVmax was calculated; clinical stages, presence of local extension, nodal and distantorgan metastases were recorded. The patients with SUVmax≥2.5 were divided into low and high SUVmax groupsby using the median SUVmax. The low SUVmax group consisted of 45 patients with SUVmax<10.5, the highSUVmax group consisted of 46 patients with SUVmax≥10.5. Their data were compared statistically.
Results: 91cases with SUVmax≥2.5 were included for analysis. The mean SUVmax in patients without any metastasis was7.42±2.91 and this was significantly lower than that (12.18±4.94) in patients with nodal and/or distant organmetastasis (P=0.000). In the low SUV group, 19 patients had local extension, 22 had nodal metastasis, and 9 haddistant organ metastasis. In the high SUV group, 31 patients had local extension, 37 had nodal metastasis, and18 had distant organ metastases. There was a significant difference in local extension (P =0.016), distant organmetastasis (P =0.046), and most significant difference in nodal metastasis rate (P =0.002) between the two groups.In addition, there was a moderate correlation between SUVmax and tumor size (r = 0.642, P﹤0.001), tumor stage(r = 0.546, P﹤0.001), node stage (r = 0.388, P﹤0.001), and overall stage (r = 0.445, P= 0.000).
Conclusion: Higherprimary tumor SUVmax predicts higher extensional or metastatic potential in patients with NSCLC. Patientswith higher SUVmax may need a close follow-up and more reasonable individual treatment because of theirhigher extensional and metastatic potential.