Effect of hypoxia on SUV in patients with NSCLC – Retrospective comparison between hypoxic and normoxic patients

Objectives FDG uptake in tumor is based on enhanced glycolysis and is associated with tumor hypoxia. We aimed to retrospectively answer the question whether SUV of the lung primary would be further increased in patients (pts.) with hypoxia compared to those with normoxia.

Methods N =60 pts. with NSCLC underwent whole-body FDG PET/CT which was done within 3 months before or after their blood gas analysis (BGA). 18 pts. were hypoxic (PaO₂ < 65 mmHg) and 42 pts. were normoxic (PaO₂ > 65 mmHg). The size of the lung primary was grouped in A (size 0.5-3.0 cm) and B (size > 3.0 cm); the mean and SD of group A and B was approximately matched between hypoxic and normoxic pts. from previous larger data bases, to allow for appropriate size comparison. The largest diameter and maximum SUV of the primary lesion were measured and compared using independent t-tests.

Results PaO₂ were 60 ± 3 for hypoxic pts. and 78 ± 5 for normoxic pts., p < 0.01. For group A, there was a statistically significantly higher SUV in hypoxic pts. than in normoxic pts. (p = 0.01) but there was no statistical significance for group B.

Results ^* statistically significant, p < 0.05

Conclusions Hypoxia can result in incremental SUV increase in pts. with NSCLC as compared to those with normoxia; this affect is evident in primary lesions of 0.5- 3.0 cm, likely due to their relatively small sizes that contain substantial viable tumor cells. However, there may be no further SUV increase in lesions > 3.0 cm, probably due to drastic tumor necrosis both in hypoxic and normoxic pts.