¹⁸F-FDG PET/CT total lesion glycolysis is associated with circulating tumor cell counts in patients with stage I to IIIA non-small cell lung cancer

Background: In non-small cell lung cancer (NSCLC), ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) uptake determined by PET and presence of circulating tumor cells (CTCs) in the peripheral blood independently predict outcomes. For ¹⁸F-FDG PET/CT staging interpretation, standardized uptake values (SUV_max/avg) are routinely used in clinical reporting. The goal was to investigate whether ¹⁸F-FDG uptake measured by SUV_max/avg, but also measures of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) (MTV × SUV_avg), are associated with CTCs. Methods: Prospectively, 7.5 mL blood was drawn from NSCLC patients at the time of staging 18F-FDG PET/CT and from healthy control subjects. CTCs were identified by immunofluorescent staining (CK8/18/19^pos/EpCAM^pos/CD45^neg/DAPI^pos nucleus). ¹⁸F-FDG PET/CTs were analyzed for SUV_max, SUV_avg, MTV, and TLG. Results: In 16 NSCLC patients with stage I–IIIA, MTV and TLG, in contrast to SUV_max and SUV_avg, were positively associated with CTCs (linear regression analysis). No CTCs were detectable in 20 healthy control subjects. Conclusions: This pilot study demonstrates that ¹⁸F-FDG PET/CT TLG correlates with CTCs in NSCLC patients without distant metastases. TLG might be a more appropriate marker for hematogenous micrometastatic potential than SUVs.