PET standardized uptake values of primary lung cancer for comparison with tumor volume doubling times

Objective: To determine the relationship between two documented indicators of tumor aggressiveness, SUV and volume doubling time (VDT) for stage I non-small cell lung cancer (NSCLC). Methods: 116 pathology proven solid NSCLC patients with 2 pretreatment CT and 1 PET/CT scan were retrospectively identified. The 2 CT scans were at least 85 days apart. SUV values were collected from PET/CT reports and CT derived VDT's were calculated assuming an exponential growth rate. Corrected SUV values were also obtained for all cases. Median VDT, SUV and corrected SUV values were reported according to cancer histology. Relationships between VDT, SUV and corrected SUV were examined. Results: 91 Adenocarcinomas and 25 squamous-cell carcinomas had median VDT values of 150.6 and 110.0 days respectively. Median SUV values were 5.1 and 12.3 for adenocarcinoma and squamous-cell carcinoma, respectively (p = 0.0003); median corrected SUV values were 16.8 and 31.7 respectively (p = 0.003). A statistically significant monotonic relationship was observed between increased SUV uptake and faster VDT (p = 0.05) and corrected SUV and VDT (P = 0.0002). When stratified by cancer histology, the relationship between VDT and either SUV or corrected SUV was statistically significant for adenocarcinomas (p = 0.02 and p = 0.0001, respectively), but not for squamous-cell carcinoma (p = 0.85 and p = 0.37, respectively). Conclusion: We demonstrated an overall significant relationship between VDT, SUV and corrected SUV. The relationship, however, was stronger for adenocarcinomas than for squamous-cell carcinomas. This implies that the primary determinant for these relationships is histology and within each cell type, there are other factors that have strong influences.